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HTML
2375 lines
119 KiB
HTML
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<!-- saved from url=(0055)https://alienbill.com/2600/101/docs/stella.html#ednotes -->
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<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
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<title>
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Stella Programmer's Guide (Unofficial HTML version)
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</title>
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</head>
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<body>
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<center>
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<h2>
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STELLA<br>
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PROGRAMMER'S<br>
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GUIDE<br>
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</h2>
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by Steve Wright 12/03/79<p>
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Reconstructed by Charles Sinnett 6/11/93<br>
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Email: cas@mentor.cc.purdue.edu</p><p>
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HTMLified by B. Watson 9/14/2001<br>
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Email: atari@hardcoders.org<br>
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<i><a href="https://alienbill.com/2600/101/docs/stella.html#ednotes">(Editor's notes --BW)</a></i>
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</p></center>
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<p>
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</p><h3>TABLE OF CONTENTS</h3>
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<ul>
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<li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#tvprot">TELEVISION PROTOCOL</a>
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<ul>
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<li>
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<a href="https://alienbill.com/2600/101/docs/diagram1.gif">Diagram 1 - Atari TV Frame</a>
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</li></ul>
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</li><li><a href="https://alienbill.com/2600/101/docs/stella.html#tiaprog">The TIA (as seen by the programmer)</a>
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<ul>
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<li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#tiaprog1.0">1.0 General Description</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#tiaprog2.0">2.0 The Registers</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#tiaprog3.0">3.0 Synchronization</a>
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<ul>
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<li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#tiaprog3.1">3.1 Horizontal Timing</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#tiaprog3.2">3.2 Microprocessor Synchronization</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#tiaprog3.3">3.3 Vertical timing</a>
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</li></ul>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#tiaprog4.0">4.0 Color and Luminosity</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#tiaprog5.0">5.0 Playfield</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#tiaprog6.0">6.0 The Moveable Objects Graphics</a>
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<ul>
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<li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#tiaprog6.1">6.1 Missile Graphics (M0, M1)</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#tiaprog6.2">6.2 Ball Graphics (BL)</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#tiaprog6.3">6.3 Player Graphics (P0, P1)</a>
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</li></ul>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#tiaprog7.0">7.0 Horizontal Positioning</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#tiaprog8.0">8.0 Horizontal Motion</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#tiaprog9.0">9.0 Object Priorities</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#tiaprog10.0">10.0 Collisions</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#tiaprog11.0">11.0 Sound</a>
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<ul>
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<li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#tiaprog11.1">11.1 Tone</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#tiaprog11.2">11.2 Frequency</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#tiaprog11.3">11.3 Volume</a>
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</li></ul>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#tiaprog12.0">12.0 Input Ports</a>
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<ul>
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<li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#tiaprog12.1">12.1 Dumped Input Ports (INPT0 thru INPT3)</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#tiaprog12.2">12.2 Latched Input Ports (INPT4, INPT5)</a>
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</li></ul>
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</li></ul>
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</li><li>
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THE PIA (6532)
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<ul>
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<li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#pia1.0">1.0 General</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#pia2.0">2.0 Interval timer</a>
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<ul>
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<li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#pia2.1">2.1 Setting the timer</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#pia2.2">2.2 Reading the timer</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#pia2.3">2.3 When the timer reaches zero</a>
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</li></ul>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#pia3.0">3.0 RAM</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#pia4.0">4.0 The I/O ports</a>
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<ul>
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<li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#pia4.1">4.1 Port B - Console Switches (read only)</a>
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</li></ul>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#pia5.0">5.0 Port A - Hand Controllers</a>
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<ul>
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<li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#pia5.1">5.1 Setting for input or output</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#pia5.2">5.2 Inputting and Outputting</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#pia5.3">5.3 Joystick Controllers</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#pia5.4">5.4 Paddle (pot) controllers</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#pia5.5">5.5 Keyboard controllers</a>
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</li></ul>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#pia6.0">6.0 Address summary table</a>
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</li></ul>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#palsecam">PAL/SECAM CONVERSIONS</a>
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<ul>
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<li>
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PAL
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</li><li>
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SECAM
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</li></ul>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#tia1a">
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TIA 1A - TELEVISION INTERFACE ADAPTOR (MODEL 1A)</a>
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<ul>
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<li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#tia1agen">
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GENERAL DESCRIPTION</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#tia1adet">
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DETAILED DESCRIPTION</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#tia1a1">1. Data and addressing</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#tia1a2">2. Synchronization</a>
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<ul>
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<li>
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A. Horizontal Timing
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</li><li>
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B. Vertical Timing
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</li><li>
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C. Composite Sync
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</li><li>
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D. Microprocessor Synchronization
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</li></ul>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#tia1a3">3. Playfield graphics Register</a>
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<ul>
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<li>
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A. Description
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</li><li>
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B. Normal Serial Output
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</li><li>
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C. Reflected Serial Output
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</li><li>
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D. Timing Constraints
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</li></ul>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#tia1a4">4. Horizontal Position Counters</a>
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<ul>
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<li>
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A. Description
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</li><li>
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B. Ball position Counter
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</li><li>
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C. Player Position Counters
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</li><li>
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D. Missile Position Counters
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</li></ul>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#tia1a5">5. Horizontal Motion Registers</a>
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<ul>
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<li>
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A. General Description
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</li><li>
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B. Timing constraints
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</li></ul>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#tia1a6">6. Moving Object Graphics Registers</a>
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<ul>
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<li>
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A. General Description
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</li><li>
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B. Missile Graphics
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</li><li>
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C. Player Graphics
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</li><li>
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D. Vertical Delay
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</li><li>
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E. Ball Graphics
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</li></ul>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#tia1a7">7. Collision Detection Latches</a>
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<ul>
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<li>
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A. Definitions
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</li><li>
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B. Reading Collision
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</li><li>
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C. Reset
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</li></ul>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#tia1a8">8. Input ports</a>
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<ul>
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<li>
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A. General Description
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</li><li>
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B. Dumped Input Ports (I0 through I3)
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</li><li>
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C. Latched Input ports (I4, I5)
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</li></ul>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#tia1a8.5">8.5 Priority Encoder</a>
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<ul>
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<li>
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A. Purpose
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</li><li>
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B. Priority Assignment
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</li><li>
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C. Priority Control
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</li></ul>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#tia1a9">9. Color Luminance Registers</a>
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<ul>
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<li>
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A. Description
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</li><li>
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B. Multiplexing
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</li></ul>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#tia1a10">10. Color Phase Shifter</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#tia1a11">11. Audio Circuits</a>
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<ul>
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<li>
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A. Frequency Select
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</li><li>
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B. Noise-Tone Generator
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</li><li>
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C. Volume Select
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</li></ul>
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</li></ul>
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<i>(These images are links to external files. --BW)</i>
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<ul>
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<li>
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<a href="https://alienbill.com/2600/101/docs/figure1.gif">Figure 1. Vertical Delay</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/figure2.gif">Figure 2. Synchronization<br>
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Figure 3. Color-Luminance</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/figure4.gif">Figure 4. Typical Horizontal Motion Circuit</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/figure5.gif">Figure 5. Playfield Graphics</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/figure6.gif">Figure 6. Collision Detection</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/figure7.gif">Figure 7. Audio Circuit</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/figure8.gif">Figure 8. Input Ports</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/figure9.gif">Figure 9. Game System</a>
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</li></ul>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#W">Write Address Detailed Functions</a>
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<ul>
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<li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#WSYNC">WSYNC (wait for sync)</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#RSYNC">RSYNC (reset sync)</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#VSYNC">VSYNC</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#VBLANK">VBLANK</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#PJ">PF0 (PF1, PF2)</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#PLAYFIELD">PLAYFIELD REGISTERS SERIAL OUTPUT</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#CTRLPF">CTRLPF</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#NUSIZ">NUSIZ0 (NUSIZ1)</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#RESP">RESP0 (RESP1, RESM0, RESM1, RESBL)</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#RESMP">RESMP0 (RESMP1)</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#HMOVE">HMOVE</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#HMCLR">HMCLR</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#HMP">HMP0 (HMP1, HMM0, HMM1, HMBL)</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#ENAM">ENAM0 (ENAM1, ENABL)</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#GRP">GRP0 (GRP1)</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#REFP">REFP0 (REFP1)</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#VDELP">VDELP0 (VDELP1, VDELBL)</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#CXCLR">CXCLR</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#COLUP">COLUP0 (COLUP1, COLUPF, COLUBK)</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#AUDF">AUDF0 (AUDF1)</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#AUDC">AUDC0 (AUDC1)</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#AUDV">AUDV0 (AUDV1)</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#wsummary">WRITE ADDRESS SUMMARY</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/stella.html#rsummary">READ ADDRESS SUMMARY</a>
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</li></ul>
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<hr>
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<i>(These documents are in separate files, to help speed
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loading of this page... Ghods know it already takes forever! --BW)</i>
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<ul>
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<li>
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<a href="https://alienbill.com/2600/101/docs/diagram2.gif">
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TIA O0..02 AND LUM TIMING</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/diagram3.gif">
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TIA WRITE TIMING CHARACTERISTICS</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/diagram4.gif">
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TIA READ TIMING CHARACTERISTICS</a>
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/diagram5.gif">
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TIA COMP-SYN AND READY TIMING</a>
|
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/diagram6.gif">
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RSYNC, RES0O, H01, H02, SHB, 02, 0O</a>
|
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</li><li>
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<a href="https://alienbill.com/2600/101/docs/diagram7.gif">
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TIA RSYNC AND BLANK AND READY TIMING</a>
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</li></ul>
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</li></ul>
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<hr>
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<a name="tvprot"></a>
|
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<h3>TELEVISION PROTOCOL</h3><p>
|
|
(The TV picture according to Atari)<br>
|
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</p><blockquote>
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|
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For the purposes of Stella programming, a single television "frame" consists
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|
of 262 horizontal lines, and each line is divided by 228 clock counts
|
|
(3.58MHz). The actual TV picture is drawn line by line from the top down
|
|
60 times a second, and actaully consists of only a portion of the entire
|
|
"frame" (see diag. #1). A typical frame will consists of 3 vertical sync
|
|
(VSYNC) lines*, 37 vertical blank (VBLANK) lines, 192 TV picture lines,
|
|
and 30 overscan lines. Atari's research has shown that this pattern will
|
|
work on all types of TV sets. Each scan lines starts with 68 clock counts of
|
|
horizontal blank (not seen on the TV screen) followed by 160 clock counts to
|
|
fully scan one line of TV picture. When the electron beam reaches the end
|
|
of a scan line, it returns to the left side of the screen, waits for the 68
|
|
horizontal blank clock counts, and proceeds to draw the next line below.
|
|
<p>
|
|
All horizontal timing is taken care of by hardware, but the microprocessor
|
|
must "manually" control vertical timing to signal the start of the next
|
|
frame. When the last line of the previous frame is detected, the
|
|
microprocessor must generate 3 lines of VSYNC, 37 lines of VBLANK, 192
|
|
lines of actual TV picture, and 30 lines of overscan. Fortunately, both
|
|
VSYNC and VBLANK can simply be turned on and off at the appropriate
|
|
times, freeing the microprocessor for other activities during their execution.
|
|
|
|
</p><p>
|
|
* (to signal the TV set to start a new frame)
|
|
|
|
</p><p>
|
|
The actual TV picture is drawn one line at a time by having the
|
|
microprocessor enter the data for that line into the Television Interface
|
|
Adaptor (TIA) chip, which then converts the data into video signals. The
|
|
TIA can only have data in it that pertains to the line being currently drawn,
|
|
so the microprocessor must be "one step ahead" of the electron beam on each
|
|
line. Since one microprocessor machine cycle occurs every 3 clock counts,
|
|
the programmer has only 76 machine cycles per line (228/3 = 76) to
|
|
construct the actual picture (actually less because the microprocessor must
|
|
be ahead of the raster). To allow more time for the software, it is customary
|
|
(but not required) to update the TIA every two scan lines. The portion of
|
|
the program that constructs this TV picture is referred to as the "Kernel", as
|
|
it is the essence or kernel of the game.
|
|
|
|
</p><p>
|
|
In general, the remaining 70 scan lines (3 for VSYNC, 37 for VBLANK, and
|
|
30 for overscan) will provides 5,320 machine cycles (70 lines x 76 machine
|
|
cycles) for housekeeping and game logic. Such activities as calculating the
|
|
new position of a player, updating the score, and checking for new inputs
|
|
are typically done during this time.
|
|
|
|
</p><p>
|
|
|
|
<a href="https://alienbill.com/2600/101/docs/diagram1.gif">Diagram 1 - Atari TV Frame</a>
|
|
</p></blockquote>
|
|
<hr>
|
|
|
|
<a name="tiaprog"></a>
|
|
<h3>The TIA (as seen by the programmer)</h3><p>
|
|
|
|
<a name="tiaprog1.0"></a>
|
|
1.0 General Description</p><p>
|
|
</p><blockquote>
|
|
The TIA is a custom IC designed to create the TV picture and sound from
|
|
the instructions sent to it by the microprocessor. It converts the 8 bit
|
|
parallel data from the microprocessor into signals that are sent to video
|
|
modulation circuits which combine and shape those signals to be compatible
|
|
with ordinary TV reception. A "playfield" and 5 moveable objects can be
|
|
created and manipulated by software.
|
|
<p>
|
|
A playfield consisting of walls, clouds, barriers, and other seldom moved
|
|
objects can be created over a colored background. The 5 moveable objects
|
|
can be positioned anywhere, and consists of 2 players, 2 missiles, and a ball.
|
|
The playfield, players, missiles, and ball are created and manipulated by a
|
|
series of registers in the TIA that the microprocessor can address and write
|
|
into. Each type of object has certain defined capabilities. For example, a
|
|
player can be moved with one instruction, but the playfield must be
|
|
completely re-drawn in order to make it "move".
|
|
</p><p>
|
|
Color and luminosity (brightness) can be assigned to the background,
|
|
playfield, and 5 moveable objects. Sound can also be generated and
|
|
controlled for volume, pitch, and type of sound. Collisions between the
|
|
various objects on the TV screen are detected by the TIA and can be read by
|
|
the microprocessor . Input ports which can be read by the microprocessor
|
|
give the status of some of the various hand held controllers.
|
|
</p><p>
|
|
</p></blockquote>
|
|
<a name="tiaprog2.0"></a>
|
|
2.0 The Registers
|
|
<p>
|
|
</p><blockquote>
|
|
All instructions to the TIA are achieved by addressing and writing to
|
|
various registers in the chip. A key point to remember is data written in a
|
|
register is latched an retained until altered by another write operation into
|
|
that register. For example, if the color register for a player is set for red,
|
|
that player will be red every time it is drawn until that color register is
|
|
changed. All of the registers are addressed by the microprocessor as part of
|
|
the overall RAM/ROM memory space.
|
|
<p>
|
|
All registers have fixed address locations and pre-assigned address names for handy
|
|
reference. Many registers do not use all 8 data bits, and some registers are used to
|
|
"strobe" or trigger events. A "strobe" register executes its function the instant it is
|
|
written to (the data written is ignored). The only registers the microprocessor can read
|
|
are the collision registers and input port registers. These registers are conveniently
|
|
arranged so that the data bits of interest always appear as data bits 6 or 7 for easy access.
|
|
</p><p>
|
|
|
|
</p></blockquote>
|
|
|
|
<a name="tiaprog3.0"></a>
|
|
3.0 Synchronization<p>
|
|
</p><p>
|
|
</p><blockquote>
|
|
<a name="tiaprog3.1"></a>
|
|
3.1 Horizontal Timing
|
|
<blockquote>
|
|
When the electron beam scans across the TV screen and reaches the right
|
|
edge, it must be turned off and moved back to the left edge of the screen to
|
|
begin the next scan line. The TIA takes care of this automatically,
|
|
independent of the microprocessor. A 3.58 MHz oscillator generates clock
|
|
pulses called "color clocks" which go into a pulse counter in the TIA. This
|
|
counter allows 160 color clocks for the beam to reach the right edge, then
|
|
generates a horizontal sync signal (HSYNC) to return the beam to the left
|
|
edge. It also generates the signal to turn the beam off (horizontal blanking)
|
|
during its return time of 68 color clocks. Total round trip for the electron
|
|
beam is 160 + 68 = 228 color clocks. Again, all the horizontal timing is
|
|
taken care of by the TIA without assistance from the microprocessor.
|
|
<p>
|
|
</p></blockquote>
|
|
<a name="tiaprog3.2"></a>
|
|
3.2 Microprocessor Synchronization
|
|
<blockquote>
|
|
The microprocessor's clock is the 3.58 MHz oscillator divided by 3, so one
|
|
machine cycle is 3 color clocks. Therefore, one complete scan line of 228
|
|
color clocks allows only 76 machine cycles (228/3 = 76) per scan line. The
|
|
microprocessor must be synchronized with the TIA on a line-by-line basis,
|
|
but program loops and branches take unpredictable lengths of time. To
|
|
solve this software sync. problem, the programmer can use the <a href="https://alienbill.com/2600/101/docs/stella.html#WSYNC">WSYNC</a>
|
|
(Wait for SYNC) strobe register. Simply writing to the WSYNC causes the
|
|
microprocessor to halt until the electron beam reaches the right edge of the
|
|
screen, then the microprocessor resumes operation at the beginning of the
|
|
68 color clocks for horizontal blanking. Since the TIA latches all
|
|
instructions until altered by another write operation, it could be updated
|
|
every 2 or 3 lines. The advantage is the programmer gains more time to
|
|
execute software, but at a price paid with lower vertical resolution in the
|
|
graphics.
|
|
<p>
|
|
NOTE: WSYNC and all the following addresses' bit structures are itemized
|
|
in the TIA hardware manual. The purpose of this document is to make
|
|
them understandable.
|
|
</p><p>
|
|
</p></blockquote>
|
|
<a name="tiaprog3.3"></a>
|
|
3.3 Vertical timing
|
|
<blockquote>
|
|
When the electron beam has scanned 262 lines, the TV set must be signaled
|
|
to blank the beam and position it at the top of the screen to start a new
|
|
frame. This signal is called vertical sync, and the TIA must transmit this
|
|
signal for at least 3 scan lines. This is accomplished by writing a "1" in D1
|
|
of <a href="https://alienbill.com/2600/101/docs/stella.html#VSYNC">VSYNC</a> to turn it on, count at least 2 scan lines, then write a "0" to D1 of
|
|
VSYNC to turn it off.
|
|
<p>
|
|
To physically turn the beam off during its repositioning time, the TV set
|
|
needs 37 scan lines of vertical blanks signal from the TIA. This is
|
|
accomplished by writing a "1" in D1 of <a href="https://alienbill.com/2600/101/docs/stella.html#VBLANK">VBLANK</a> to turn it on, count 37
|
|
lines, then write a "0" to D1 of VBLANK to turn it off. The microprocessor
|
|
is of course free to execute other software during the vertical timing
|
|
commands, VSYNC and VBLANK.
|
|
</p><p>
|
|
</p></blockquote>
|
|
</blockquote>
|
|
<a name="tiaprog4.0"></a>
|
|
4.0 Color and Luminosity
|
|
<p>
|
|
</p><blockquote>
|
|
Color and luminosity can be assigned to the background (BK), playfield
|
|
(PF), ball (BL), player 0 (P0), player 1(P1), missile 0 (M0), and missile 1
|
|
(M1). There are only four color-lum registers for these 7 objects, so the
|
|
objects are paired to share the same register according to the following list:
|
|
<p>
|
|
</p><blockquote>
|
|
<table border="1">
|
|
<tbody><tr>
|
|
<td>color-lum register</td> <td>Objects colored</td></tr>
|
|
<tr><td>COLUMP0</td> <td>P0, M0 (player 0, missile 0)</td></tr>
|
|
<tr><td>COLUMP1</td> <td>P1, M1 (player 1, missile 1)</td></tr>
|
|
<tr><td>COLUMPF</td> <td>PF, BL (playfield, ball)</td></tr>
|
|
<tr><td>COLUMBK</td> <td>BK (background)</td></tr>
|
|
</tbody></table>
|
|
</blockquote>
|
|
<p>
|
|
For example, if the <a href="https://alienbill.com/2600/101/docs/stella.html#COLUP">COLUMP0</a> register is set for light red, both P0 and M0
|
|
will be light red when drawn.
|
|
</p><p>
|
|
A color-lum register is set for both color and luminosity by writing a single 7
|
|
bit instruction to that register. Four of the bits select one of the 16
|
|
available colors, and the other 3 bits select one of 8 levels of luminosity
|
|
(brightness). The specific codes required to create specific color and lum are
|
|
listed in the Detailed Address List of the TIA hardware manual. As with all
|
|
registers (except the "strobe" registers), the data written to them is latched
|
|
until altered by another write operation.
|
|
</p><p>
|
|
<i>(These registers are referred to here as COLUMxx, but everywhere else
|
|
they are COLUxx, including later in this document. --BW)</i>
|
|
</p></blockquote>
|
|
<a name="tiaprog5.0"></a>
|
|
5.0 Playfield
|
|
<p>
|
|
</p><blockquote>
|
|
The <a href="https://alienbill.com/2600/101/docs/stella.html#PF">PF</a> register is used to create a playfield of walls, clouds, barriers, etc., that are
|
|
seldom moved. This low resolution register is written into to draw the left half of the
|
|
TV screen only. The right half of the screen is drawn by software selection of whether a
|
|
duplication or a reflection of the right half.
|
|
<p>
|
|
The PF register is 20 bits wide, so the 20 bits are written into 3 addresses:
|
|
PF0, PF1, and PF2. PF0 is only 4 bits wide and constructs the first 4 "bits"
|
|
of the playfield, starting at the left edge of the TV screen. PF1 constructs
|
|
the next 8 "bits", and PF2 the last 8 bits" which end at the center of the
|
|
screen. The PF register is scanned from left to right and where a "1" is
|
|
found the PF color is drawn, and where a "0" is found, the BK color is
|
|
drawn. To clear the playfield, obviously zeros must be written into PF0,
|
|
PF1, and PF2.
|
|
</p><p>
|
|
To make the right half of the playfield into a duplication or copy of the left
|
|
half, a "0" is written to D0 of the <a href="https://alienbill.com/2600/101/docs/stella.html#CTRLPF">CTLPF</a> (control playfield) register.
|
|
Writing a "1" will cause the reflection to be displayed.
|
|
</p></blockquote>
|
|
<p>
|
|
<a name="tiaprog6.0"></a>
|
|
6.0 The Moveable Objects Graphics
|
|
</p><blockquote>
|
|
<p>
|
|
All 5 moveable objects (P0, M0, P1, M1, BL) can be assigned a horizontal
|
|
location on the screen and moved left or right relative to their location.
|
|
Vertical positions, however, are treated in an entirely different manner. In
|
|
principle, these objects appear at whatever scan lines their graphics
|
|
registers are enabled. For example, let us assume the ball is to be
|
|
positioned vertically in the center of the screen. The screen has 192 scan
|
|
lines and we want the ball to be 2 scan lines "thick". The ball graphics
|
|
would be disabled until scan line 96, enabled for 2 scan lines, then disabled
|
|
for the rest of the frame. Each type of object (players, missiles, and ball)
|
|
has its own characteristics and limitations.
|
|
</p><p>
|
|
</p></blockquote>
|
|
<a name="tiaprog6.1"></a>
|
|
6.1 Missile Graphics (M0, M1)
|
|
<blockquote>
|
|
The two missile graphics registers will draw a missile on any scan line by
|
|
writing a "1" to the one bit enable missile registers (<a href="https://alienbill.com/2600/101/docs/stella.html#ENAM">ENAM0</a>, ENAM1).
|
|
Writing a "0" to these registers will disable the graphics. The missiles' left
|
|
edge is positioned by a horizontal position register, but the right edge is a
|
|
function of how wide the missile is make. Width of a missile is controlled by
|
|
writing into bits D4 and D5 of the number-size registers (<a href="https://alienbill.com/2600/101/docs/stella.html#NUSIZ">NUSIZ0</a>,
|
|
NUSIZ1). This has the effect of "stretching" the missile out over 1,2,4, or 8
|
|
color clock counts (a full scan line is 160 color clocks).
|
|
<p>
|
|
</p></blockquote>
|
|
<a name="tiaprog6.2"></a>
|
|
6.2 Ball Graphics (BL)
|
|
<blockquote>
|
|
The ball graphics register works just like the missile registers. Writing a
|
|
"1" to the enable ball register (<a href="https://alienbill.com/2600/101/docs/stella.html#ENABL">ENABL</a>) enables the ball graphics until the
|
|
register is disabled. The ball can also be "stretched" to widths of 1, 2, 4, or 8
|
|
color clock counts by writing to bits D4 and D5 of the <a href="https://alienbill.com/2600/101/docs/stella.html#CTRLPF">CTRLPF</a> register.
|
|
<p>
|
|
The ball can also be vertically delayed one can line. For example, if the ball
|
|
graphics were enabled on scan line 95, it could be delayed to not display on
|
|
the screen until scan line 96 by writing a "1" to D0 of the vertical delay
|
|
(<a href="https://alienbill.com/2600/101/docs/stella.html#VDELP">VDELBL</a>) register. The reason for having a vertical delay capability is
|
|
because most programs will update the TIA every 2 lines. This confines all
|
|
vertical movements of objects to 2 scan line "jumps". The use of vertical
|
|
delay allows the objects to move one scan line at a time.
|
|
</p><p>
|
|
</p></blockquote>
|
|
<a name="tiaprog6.3"></a>
|
|
6.3 Player Graphics (P0, P1)
|
|
<blockquote>
|
|
The player graphics are the most sophisticated of all the moveable objects.
|
|
They have all the capabilities of the missile and ball graphics, plus three
|
|
move capabilities. Players can take on a "shape" such as a man or an
|
|
airplane, and the player can easily be flipped over horizontally to display
|
|
the mirror image (reflection) instead of the original image, plus multiple
|
|
copies of the players can be created.
|
|
<p>
|
|
The player graphics are drawn line-by-line like all other graphics. The
|
|
difference here is each scan line of the player is 8 "bits" wide, whereas the
|
|
missiles and ball are one "bit" wide. Therefore, a player can be though of as
|
|
being drawn of graph paper 8 squares wide and as tall as desired. To "color
|
|
in the squares" of this imaginary graph paper, 8 data bits are written into
|
|
the players graphics registers (<a href="https://alienbill.com/2600/101/docs/stella.html#GRP">GP0</a>, GP1). This 8 bit register is scanned
|
|
from D7 to D0, and wherever a "1" is found that "square" gets the players'
|
|
color (from the color-lum register) and where a "0" is found that "square"
|
|
gets the background color. To position a player vertically, simply leave all
|
|
"0's" in the graphics registers (GP0, GP1) until the electron beam is on the
|
|
scan line desired, write to the graphics register line-by-line describing the
|
|
player, then write all "0's" to turn off the players' graphics until the end of
|
|
that frame.
|
|
</p><p>
|
|
To display a mirror image (reflection) instead of the original figure, write a
|
|
"1" to D3 of the one bit reflection register (<a href="https://alienbill.com/2600/101/docs/stella.html#REFP">REFP0</a>, REFP1). A "0" written to
|
|
these registers restores the original figure.
|
|
</p><p>
|
|
Multiple copies of players as well as their size are controlled by writing 3
|
|
bits (D0, D1, D2) into the number-size registers (<a href="https://alienbill.com/2600/101/docs/stella.html#NUSIZ">NUSIZ0</a>, NUSIZ1). These
|
|
three bits select from 1 to 3 copies of the player, spacing of those copies, as
|
|
well as the size of the player (each "square" of the player can be 1, 2, or 4
|
|
clocks wide). Whenever multiple copies are selected, the TIA automatically
|
|
creates the same number of copies of the missile for that player. Again, the
|
|
specifics of all this are laid out in the TIA hardware manual.
|
|
</p><p>
|
|
Vertical delay for the players works exactly like the ball by writing a "1" to
|
|
D0 in the players' vertical delay registers (<a href="https://alienbill.com/2600/101/docs/stella.html#VDELP">VDELP0</a>, VDELP1). Writing a
|
|
"0" to these locations disables the vertical delay.
|
|
</p><p>
|
|
</p></blockquote>
|
|
<a name="tiaprog7.0"></a>
|
|
7.0 Horizontal Positioning
|
|
<blockquote>
|
|
<p>
|
|
The horizontal position of each object is set by writing to its associated reset
|
|
register (<a href="https://alienbill.com/2600/101/docs/stella.html#RESP">RESP0</a>, RESP1, <a href="https://alienbill.com/2600/101/docs/stella.html#RESM">RESM0</a>, RESM1, <a href="https://alienbill.com/2600/101/docs/stella.html#RESBL">RESBL</a>) which are all "strobe"
|
|
registers (they trigger their function as soon as they are addressed). That
|
|
causes the object to be positioned wherever the electron bean was in its
|
|
sweep across the screen when the register was reset. for example, if the
|
|
electron beam was 60 color clocks into a scan line when RESP0 was written
|
|
to, player 0 would be positioned 60 color clocks "in" on the next scan line.
|
|
Whether or not P0 is actually drawn on the screen is a function of the data
|
|
in the <a href="https://alienbill.com/2600/101/docs/stella.html#GRP">GP0</a> register, but if it were drawn, it would show up at 60. Resets to
|
|
these registers anywhere during horizontal blanking will position objects at
|
|
the left edge of the screen (color clock 0). Since there are 3 color clocks per
|
|
machine cycle, and it can take up to 5 machine cycles to write the register,
|
|
the programmer is confined to positioning the objects at 15 color clock
|
|
intervals across the screen. This "course" positioning is "fine tuned" by the
|
|
Horizontal Motion, explained in section 8.0.
|
|
</p><p>
|
|
Missiles have an additional positioning command. Writing a "1" to D1 of
|
|
the reset missile-to-player register (<a href="https://alienbill.com/2600/101/docs/stella.html#RESMP">RESMP0</a>, RESMP1) disables that
|
|
missiles' graphics (turns it off) and repositions it horizontally to the center
|
|
of its associated player. Until a "0" is written to the register, the missile's
|
|
horizontal position is locked to the center of its player in preparation to be
|
|
fired again.
|
|
</p><p>
|
|
</p></blockquote>
|
|
<a name="tiaprog8.0"></a>
|
|
8.0 Horizontal Motion
|
|
<blockquote>
|
|
<p>
|
|
Horizontal motion allows the programmer to move any of the 5 graphics
|
|
objects relative to their current horizontal position. Each object has a 4 bit
|
|
horizontal motion register (<a href="https://alienbill.com/2600/101/docs/stella.html#HMP">HMP0</a>, HMP1, <a href="https://alienbill.com/2600/101/docs/stella.html#HMM">HMM0</a>, HMM1, <a href="https://alienbill.com/2600/101/docs/stella.html#HMBL">HMBL</a>) that can
|
|
be loaded with a value in the range of +7 to -8 (negative values are
|
|
expressed in two's complement from). This motion is not executed until the
|
|
<a href="https://alienbill.com/2600/101/docs/stella.html#HMOVE">HMOVE</a> register is written to, at which time all motion registers move their
|
|
respective objects. Objects can be moved repeatedly by simply executing
|
|
HMOVE. Any object that is not to move must have a 0 in its motion
|
|
register. With the horizontal positioning command confined to positioning
|
|
objects at 15 color clock intervals, the motion registers fills in the gaps by
|
|
moving objects +7 to -8 color clocks. Objects can not be placed at any color
|
|
clock position across the screen. All 5 motion registers can be set to zero
|
|
simultaneously by writing to the horizontal motion clear register (<a href="https://alienbill.com/2600/101/docs/stella.html#HMCLR">HMCLR</a>).
|
|
</p><p>
|
|
There are timing constraints for the HMOVE command. The HMOVE
|
|
command must immediately follow a <a href="https://alienbill.com/2600/101/docs/stella.html#WSYNC">WSYNC</a> (Wait for SYNC) to insure the
|
|
HMOVE operation occurs during horizontal blanking. This is to allow
|
|
sufficient time for the motion registers to do their thing before the electron
|
|
beam starts drawing the next scan line. Also, for mysterious internal
|
|
hardware considerations, the motion registers should not be modified for at
|
|
least 24 machine cycles after an HMOVE command.
|
|
</p><p>
|
|
</p></blockquote>
|
|
<a name="tiaprog9.0"></a>
|
|
9.0 Object Priorities
|
|
<blockquote>
|
|
<p>
|
|
Each object is assigned a priority so when any two objects overlap the one
|
|
with the highest priority will appear to move in front of the other. To
|
|
simplify hardware logic, the missiles have the same priority as their
|
|
associated player, and the ball has the same priority as the playfield. The
|
|
background, of course, has the lowest priority. The following table
|
|
illustrates the normal (default) priority assignments.
|
|
</p><p>
|
|
</p><blockquote>
|
|
<table border="1">
|
|
<tbody><tr><td>Priority</td> <td>Objects</td></tr>
|
|
<tr><td>1</td> <td>P0, M0</td></tr>
|
|
<tr><td>2</td> <td>P1, M1</td></tr>
|
|
<tr><td>3</td> <td>BL, PF</td></tr>
|
|
<tr><td>4</td> <td>BK</td></tr>
|
|
</tbody></table>
|
|
</blockquote>
|
|
<p>
|
|
This priority assignment means that players and missiles will move in front
|
|
of the playfield. To make the players and missiles move behind the
|
|
playfield, a "1" must be written to D2 of the <a href="https://alienbill.com/2600/101/docs/stella.html#CTRLPF">CTRLPF</a> register. The
|
|
following table illustrates how the priorities are affected:
|
|
</p><p>
|
|
</p><blockquote>
|
|
<table border="1">
|
|
<tbody><tr><td>Priority</td> <td>Objects</td></tr>
|
|
<tr><td>1</td> <td>BL, PF</td></tr>
|
|
<tr><td>2</td> <td>P0, M0</td></tr>
|
|
<tr><td>3</td> <td>P1, M1</td></tr>
|
|
<tr><td>4</td> <td>BK</td></tr>
|
|
</tbody></table>
|
|
</blockquote>
|
|
<p>
|
|
One more priority control is available to be used for displaying the score.
|
|
When a "1" is written to D1 of the CTRLPF register, the left half of the
|
|
playfield takes on the color of player 0, and the right half the color of player
|
|
1. The game score can now be displayed using the <a href="https://alienbill.com/2600/101/docs/stella.html#PF">PF</a> graphics register, and
|
|
the score will be in the same color as its associated player.
|
|
</p><p>
|
|
</p></blockquote>
|
|
<a name="tiaprog10.0"></a>
|
|
10.0 Collisions
|
|
<blockquote>
|
|
<p>
|
|
The TIA detects collisions between any of the 6 objects it generates (the
|
|
playfield and 5 moveable objects). There are 15 possible two-object
|
|
collisions which are stored in 15 one bit latches. Each collision register
|
|
contains two of these latches which are read by the microprocessor on D6
|
|
and D7 of the data bus for easy access. A "1" on the data line indicates the
|
|
collision it records has occurred. The collision registers could be read at any
|
|
time but is usually done during vertical blank after all possible collisions
|
|
have occurred. The collision registers are all reset simultaneously by
|
|
writing to the collision reset register (<a href="https://alienbill.com/2600/101/docs/stella.html#CXCLR">CXCLR</a>).
|
|
</p><p>
|
|
</p></blockquote>
|
|
<a name="tiaprog11.0"></a>
|
|
11.0 Sound
|
|
<blockquote>
|
|
<p>
|
|
There are two audio circuits for generating sound. They are identical but
|
|
completely independent and can be operated simultaneously to produce
|
|
sound effects through the TV speaker. Each audio circuit has three
|
|
registers that control a noise-tone generator (what kind of sound), a
|
|
frequency selection (high or low pitch of the sound), and a volume control.
|
|
</p><p>
|
|
<a name="tiaprog11.1"></a>
|
|
11.1 Tone
|
|
</p><blockquote>
|
|
The noise-tone generator is controlled by writing to the 4 bit audio control
|
|
registers (<a href="https://alienbill.com/2600/101/docs/stella.html#AUDC">AUDC0</a>, AUDC1). The values written cause different kinds of
|
|
sounds to be generated. Some are pure tones like a flute, others have
|
|
various "noise" content like a rocket motor or explosion. Even though the
|
|
TIA hardware manual lists the sounds created by each value, some
|
|
experimentation will be necessary to find "your sound".
|
|
<p>
|
|
</p></blockquote>
|
|
<a name="tiaprog11.2"></a>
|
|
11.2 Frequency
|
|
<blockquote>
|
|
Frequency selection is controlled by writing to a 5 bit audio frequency
|
|
register (<a href="https://alienbill.com/2600/101/docs/stella.html#AUDF">AUDF0</a>, AUDF1). The value written is used to divide a 30KHz
|
|
reference frequency creating higher or lower pitch of whatever type of sound
|
|
is created by the noise-tone generator. By combining the pure tones
|
|
available from the noise-tone generator with frequency selection a wide
|
|
range of tones can be generated.
|
|
<p>
|
|
</p></blockquote>
|
|
<a name="tiaprog11.3"></a>
|
|
11.3 Volume
|
|
<blockquote>
|
|
Volume is controlled by writing to a 4 bit audio volume register (<a href="https://alienbill.com/2600/101/docs/stella.html#AUDV">AUDV0</a>,
|
|
AUDV1). Writing 0 to these registers turns sound off completely, and
|
|
writing any value up to 15 increases the volume accordingly.
|
|
<p>
|
|
</p></blockquote>
|
|
</blockquote>
|
|
<a name="tiaprog12.0"></a>
|
|
12.0 Input Ports
|
|
<blockquote>
|
|
<p>
|
|
There are six input ports whose logic states can be read on D7 by reading
|
|
the input port addresses (INPT0, thru INPT5). These six ports are divided
|
|
into two types, "dumped" and "latched".
|
|
</p><p>
|
|
<a name="tiaprog12.1"></a>
|
|
12.1 Dumped Input Ports (INPT0 thru INPT3)
|
|
</p><blockquote>
|
|
These four ports are used to read up to four paddle controllers. Each paddle controller
|
|
contains an adjustable pot controlled by the knob on the controller. The output of the
|
|
pot is used to charge a capacitor in the console, and when the capacitor is charged the
|
|
input port goes HI. The microprocessor discharges this capacitor by writing a "1" to D7
|
|
of <a href="https://alienbill.com/2600/101/docs/stella.html#VBLANK">VBLANK</a> then measures the time it takes to detect a logic one at that port. This
|
|
information can be used to position objects on the screen based on the position of the
|
|
knob on the paddle controller.
|
|
<p>
|
|
</p></blockquote>
|
|
<a name="tiaprog12.2"></a>
|
|
12.2 Latched Input Ports (INPT4, INPT5)
|
|
<blockquote>
|
|
These two ports have latches that are both enabled by writing a "1" or
|
|
disabled by writing a "0" to D6 of <a href="https://alienbill.com/2600/101/docs/stella.html#VBLANK">VBLANK</a>. When disabled the
|
|
microprocessor reads the logic level of the port directly. When enabled, the
|
|
latch is set for logic one and remains that way until its port goes LO. When
|
|
the port goes LO the latch goes LO and remains that way regardless of what
|
|
the port does. The trigger buttons of the joystick controllers connect to
|
|
these ports.
|
|
<p>
|
|
</p></blockquote>
|
|
</blockquote>
|
|
<hr>
|
|
<a name="pia"></a>
|
|
<h3>THE PIA (6532)</h3>
|
|
<p>
|
|
<a name="pia1.0"></a>
|
|
1.0 General
|
|
</p><p>
|
|
</p><blockquote>
|
|
The PIA chip is an off-the-shelf 6532 Peripheral Interface Adaptor which
|
|
has three functions: a programmable timer, 128 bytes of RAM, and two 8
|
|
bit parallel I/O ports.
|
|
<p>
|
|
</p></blockquote>
|
|
<a name="pia2.0"></a>
|
|
2.0 Interval timer
|
|
<blockquote>
|
|
<p>
|
|
The PIA uses the same clock as the microprocessor so that one PIA cycle
|
|
occurs for each machine cycle. The PIA can be set for one of four different
|
|
"intervals", where each interval is some multiple of the clock (and therefore
|
|
machine cycles). A value from 1 to 255 is loaded into the PIA which will be
|
|
decremented by one at each interval. The timer can now be read by the
|
|
microprocessor to determine elapsed time for timing various software
|
|
operations and keep them synchronized with the hardware (TIA chip).
|
|
</p><p>
|
|
<a name="pia2.1"></a>
|
|
2.1 Setting the timer
|
|
</p><blockquote>
|
|
The timer is set by writing a value or count (from 1 to 255) to the address of
|
|
the desired interval setting according to the following table :
|
|
<p>
|
|
</p><blockquote>
|
|
<table border="1">
|
|
<tbody><tr><td>Hex Address</td> <td>Interval</td> <td> Mnemonic</td></tr>
|
|
<tr><td>294</td> <td>1 clock</td> <td>TIM1T</td></tr>
|
|
<tr><td>295</td> <td>8 clocks</td> <td>TIM8T</td></tr>
|
|
<tr><td>296</td> <td>64 clocks</td> <td>TIM64T</td></tr>
|
|
<tr><td>297</td> <td>1024 clocks</td> <td>T1024T</td></tr>
|
|
</tbody></table>
|
|
</blockquote>
|
|
<p>
|
|
For example, if the value of 100 were written to TIM64T (HEX address 296)
|
|
the timer would decrement to 0 in 6400 clocks (64 clocks per interval x 100
|
|
intervals) which would also be 6400 microprocessor machine cycles.
|
|
</p><p>
|
|
</p></blockquote>
|
|
<a name="pia2.2"></a>
|
|
2.2 Reading the timer
|
|
<blockquote>
|
|
The timer may be read any number of times after it is loaded of course, but
|
|
the programmer is usually interested in whether or not the timer has
|
|
reached 0. The timer is read by reading INTIM at hex address 284.
|
|
<p>
|
|
</p></blockquote>
|
|
<a name="pia2.3"></a>
|
|
2.3 When the timer reaches zero
|
|
<blockquote>
|
|
The PIA decrements the value or count loaded into it once each interval
|
|
until it reaches 0. It holds that 0 counts for one interval, then the counter
|
|
flips to FF(HEX) and decrements once each clock cycle, rather than once per
|
|
interval. The purpose of this feature is to allow the programmer to
|
|
determine how long ago the timer zeroed out in the event the timer was
|
|
read after it passed zero.
|
|
</blockquote>
|
|
</blockquote>
|
|
<p>
|
|
<a name="pia3.0"></a>
|
|
3.0 RAM
|
|
</p><p>
|
|
</p><blockquote>
|
|
The PIA has 128 bytes of RAM located in the Stella memory map from HEX
|
|
address 80 to FF. The microprocessor stack is normally located from FF on
|
|
down, and variables are normally located from 80 on up (hoping the two
|
|
never meet).
|
|
<p>
|
|
</p></blockquote>
|
|
<a name="pia4.0"></a>
|
|
4.0 The I/O ports
|
|
<blockquote>
|
|
<p>
|
|
The two ports (Port A and Port B) are 8 bits wide and can be set for either
|
|
input or output. Port A is used to interface to carious hand-held controllers
|
|
but Port B is dedicated to reading the status of the Stella console switches.
|
|
</p><p>
|
|
<a name="pia4.1"></a>
|
|
4.1 Port B - Console Switches (read only)
|
|
</p><blockquote>
|
|
Port B is hardwired to be an input port only that is read by addressing
|
|
SWCHB (HEX 282) to determine the status of all the console switches
|
|
according to the following table:
|
|
<p>
|
|
</p><blockquote>
|
|
<table border="1">
|
|
<tbody><tr><td>Data Bit</td> <td>Switch</td> <td>Bit Meaning</td></tr>
|
|
<tr><td>D7</td> <td>P1 difficulty</td> <td>0 = amateur (B), 1 = pro (A)</td></tr>
|
|
<tr><td>D6</td> <td>P0 difficulty</td> <td>0 = amateur (B), 1 = pro (A)</td></tr>
|
|
<tr><td>D5/D4</td> <td colspan="2">(not used)</td></tr>
|
|
<tr><td>D3</td> <td>color - B/W</td> <td>0 = B/W, 1 = color</td></tr>
|
|
<tr><td>D2</td> <td colspan="2">(not used)</td></tr>
|
|
<tr><td>D1</td> <td>game select</td> <td>0 = switch pressed</td></tr>
|
|
<tr><td>D0</td> <td>game reset</td> <td>0 = switch pressed</td></tr>
|
|
</tbody></table>
|
|
</blockquote>
|
|
</blockquote>
|
|
<p>
|
|
</p></blockquote>
|
|
<a name="pia5.0"></a>
|
|
5.0 Port A - Hand Controllers
|
|
<blockquote>
|
|
<p>
|
|
Port A is under full software control to be configured as an input or an
|
|
output port. It can then be used to read or control various hand-head
|
|
controllers with the data bits defined differently depending on the type of
|
|
controller used.
|
|
</p><p>
|
|
<a name="pia5.1"></a>
|
|
5.1 Setting for input or output
|
|
</p><blockquote>
|
|
Port A has an 8 bit wide Data Direction Register (DDR) that is written to at
|
|
SWACNT (HEX 281) to set each individual pin of Port A to either input or
|
|
output. The Port A pins are labeled PA0 thru PA7, and writing a "0" to a
|
|
pins' DDR bit sets that pin as input, and a "1" sets it as an output. For
|
|
example, writing all 0's to SWACNT (the DDR for Port A) sets PA0 thru
|
|
PA7 (all 8 pins of Port A) as inputs. If F0 (11110000) were written to
|
|
SWACNT then PA7, PA6, PA5 & PA4 would be outputs, and PA3, PA2, PA1
|
|
& PA0 would be inputs.
|
|
</blockquote>
|
|
<p>
|
|
<a name="pia5.2"></a>
|
|
5.2 Inputting and Outputting
|
|
</p><blockquote>
|
|
Once the DDR has set the pins of Port A for input or output they may be
|
|
read or written to by addressing SWCHA (HEX 280).
|
|
</blockquote>
|
|
<p>
|
|
<a name="pia5.3"></a>
|
|
5.3 Joystick Controllers
|
|
</p><blockquote>
|
|
Two joysticks can be read by configuring the entire port as input and
|
|
reading the data at SWCHA according to the following table:
|
|
<p>
|
|
</p><blockquote>
|
|
<table border="1">
|
|
<tbody><tr><td>Data Bit</td><td>Direction</td><td>Player</td></tr>
|
|
<tr><td>D7</td><td>right</td><td>P0</td></tr>
|
|
<tr><td>D6</td><td>left</td><td>P0</td></tr>
|
|
<tr><td>D5</td><td>down</td><td>P0</td></tr>
|
|
<tr><td>D4</td><td>up</td><td>P0</td></tr>
|
|
<tr><td>D3</td><td>right</td><td>P1</td></tr>
|
|
<tr><td>D2</td><td>left</td><td>P1</td></tr>
|
|
<tr><td>D1</td><td>down</td><td>P1</td></tr>
|
|
<tr><td>D0</td><td>up</td><td>P1</td></tr>
|
|
</tbody></table>
|
|
(P0 = left player, P1 = right player)
|
|
<p>
|
|
</p></blockquote>
|
|
A "0" in a data bit indicates the joystick has been moved to close that
|
|
switch. All "1's" in a player's nibble indicates that joystick is not moving.
|
|
<p>
|
|
</p></blockquote>
|
|
<a name="pia5.4"></a>
|
|
5.4 Paddle (pot) controllers
|
|
<blockquote>
|
|
Only the paddle triggers are read from the PIA. The paddles themselves
|
|
are read at INP0 thru INPT3 of the TIA. The paddle triggers can be read at
|
|
SWCHA according to the following table :
|
|
<p>
|
|
</p><blockquote>
|
|
<table border="1">
|
|
<tbody><tr><td>Data Bit</td> <td>Paddle #</td></tr>
|
|
<tr><td>D7</td> <td>P0</td></tr>
|
|
<tr><td>D6</td> <td>P1</td></tr>
|
|
<tr><td>D5/D4</td> <td>(not used)</td></tr>
|
|
<tr><td>D3</td> <td>P2</td></tr>
|
|
<tr><td>D2</td> <td>P3</td></tr>
|
|
<tr><td>D1/D0</td> <td>(not used)</td></tr>
|
|
</tbody></table>
|
|
</blockquote>
|
|
<p>
|
|
</p></blockquote>
|
|
<a name="pia5.5"></a>
|
|
5.5 Keyboard controllers
|
|
<blockquote>
|
|
The keyboard controller has 12 buttons arranged into 4 rows and 3 columns.
|
|
A signal is sent to a row, then the columns are checked to see if a button is
|
|
pushed, then the next row is signaled and all columns sensed, etc. until the
|
|
entire keyboard is scanned and sensed. The PIA sends the signals to the
|
|
rows, and the columns are sensed by reading INPT0, INPT1, and INPT4 of
|
|
the TIA. With Port A configured as an output port, the data bits will send a
|
|
signal to the keyboard controller rows according to the following table :
|
|
<p>
|
|
</p><blockquote>
|
|
<table border="1">
|
|
<tbody><tr><td>Data Bit</td><td>Keyboard Row</td><td>Player</td></tr>
|
|
<tr><td>D7</td><td>bottom</td><td>P0</td></tr>
|
|
<tr><td>D6</td><td>third</td><td>P0</td></tr>
|
|
<tr><td>D5</td><td>second</td><td>P0</td></tr>
|
|
<tr><td>D4</td><td>top</td><td>P0</td></tr>
|
|
<tr><td>D3</td><td>bottom</td><td>P1</td></tr>
|
|
<tr><td>D2</td><td>third</td><td>P1</td></tr>
|
|
<tr><td>D1</td><td>second</td><td>P1</td></tr>
|
|
<tr><td>D0</td><td>top</td><td>P1</td></tr>
|
|
</tbody></table>
|
|
(P0 = left player, P1 = right player)
|
|
<p>
|
|
NOTE : a delay of 400 microseconds is necessary between writing to this
|
|
port and reading the TIA input ports.
|
|
</p></blockquote>
|
|
</blockquote>
|
|
</blockquote>
|
|
<p>
|
|
<a name="pia6.0"></a>
|
|
6.0 Address summary table
|
|
</p><p>
|
|
</p><blockquote>
|
|
<table border="1">
|
|
<tbody><tr><td>Hex Address</td> <td>Mnemonic</td> <td>Purpose</td></tr>
|
|
<tr><td>280</td> <td>SWCHA</td> <td>Port A; input or output (read or write)</td></tr>
|
|
<tr><td>281</td> <td>SWACNT</td> <td>Port A DDR, 0= input, 1=output</td></tr>
|
|
<tr><td>282</td> <td>SWCHB</td> <td>Port B; console switches (read only)</td></tr>
|
|
<tr><td>283</td> <td>SWBCNT</td> <td>Port B DDR (hardwired as input)</td></tr>
|
|
<tr><td>284</td> <td>INTIM</td> <td>Timer output (read only)</td></tr>
|
|
<tr><td>294</td> <td>TIM1T</td> <td>set 1 clock interval (838 nsec/interval)</td></tr>
|
|
<tr><td>295</td> <td>TIM8T</td> <td>set 8 clock interval (6.7 usec/interval)</td></tr>
|
|
<tr><td>296</td> <td>TIM64T</td> <td>set 64 clock interval (53.6 usec/interval)</td></tr>
|
|
<tr><td>297</td> <td>T1024T</td> <td>set 1024 clock interval (858.2 usec/interval)</td></tr>
|
|
</tbody></table>
|
|
<p>
|
|
NOTE: one clock is also one microprocessor machine cycle
|
|
</p></blockquote>
|
|
<hr>
|
|
<p>
|
|
<a name="palsecam"></a>
|
|
</p><h3>PAL/SECAM CONVERSIONS</h3>
|
|
<p>
|
|
PAL
|
|
</p><blockquote>
|
|
1. The number of scan lines, and therefore the frame time increases from
|
|
NTSC to PAL according to the following table:
|
|
<p>
|
|
</p><blockquote>
|
|
<table border="1" width="60%">
|
|
<tbody><tr>
|
|
<td colspan="3" align="right">NTSC</td>
|
|
<td colspan="2" align="right">PAL</td>
|
|
</tr>
|
|
<tr>
|
|
<td colspan="2" align="right">scanlines</td>
|
|
<td align="right">microseconds</td>
|
|
<td align="right">scanlines</td>
|
|
<td align="right">microseconds</td>
|
|
</tr>
|
|
<tr>
|
|
<td align="left" width="40%">VBLANK</td>
|
|
<td align="right" width="15%">40</td>
|
|
<td align="right" width="15%">2548</td>
|
|
<td align="right" width="15%">48</td>
|
|
<td align="right" width="15%">3085</td>
|
|
</tr>
|
|
<tr>
|
|
<td align="left" width="40%">KERNEL</td>
|
|
<td align="right">192</td>
|
|
<td align="right">12228</td>
|
|
<td align="right">228</td>
|
|
<td align="right">14656</td>
|
|
</tr>
|
|
<tr>
|
|
<td align="left" width="40%">OVERSCAN</td>
|
|
<td align="right">30</td>
|
|
<td align="right">1910</td>
|
|
<td align="right">36</td>
|
|
<td align="right">2314</td>
|
|
</tr>
|
|
<tr>
|
|
<td align="left" width="40%">FRAME</td>
|
|
<td align="right">262</td>
|
|
<td align="right">16686</td>
|
|
<td align="right">312</td>
|
|
<td align="right">20055</td>
|
|
</tr>
|
|
</tbody></table>
|
|
</blockquote>
|
|
|
|
<p>
|
|
2. Sounds will drop a little in pitch (frequency) because of a slower crystal
|
|
clock. Some sounds may need the <a href="https://alienbill.com/2600/101/docs/stella.html#AUDF">AUDF0</a>/AUDF1 touched up.
|
|
</p><p>
|
|
3. PAL operates at 50 Hz compared to NTSC 60Hz, a 17% reduction. If
|
|
game play speed is based on frames per second, it will slow down by 17%.
|
|
This can be disastrous for most skill/action carts. If the NTSC version is
|
|
designed with 2 byte fractional addition techniques (or anything not based
|
|
on frames per second) to move objects, then PAL conversion can be as
|
|
simple as changing the fraction tables, avoiding major surgery on the
|
|
program.
|
|
</p><p>
|
|
</p></blockquote>
|
|
SECAM
|
|
<blockquote>
|
|
1. SECAM is a little weird. It takes the PAL software, but the console
|
|
color/black & white switch is hardwired as black & white. Therefore, it
|
|
reads the PAL black & white tables in software and assigns a fixed color to
|
|
each lum of black & white according to the following table:
|
|
<p>
|
|
</p><blockquote>
|
|
<table border="1">
|
|
<tbody><tr><td>Lum</td> <td>Color</td></tr>
|
|
<tr><td>0</td> <td>Black</td></tr>
|
|
<tr><td>2</td> <td>Blue</td></tr>
|
|
<tr><td>4</td> <td>Red</td></tr>
|
|
<tr><td>6</td> <td>Magenta</td></tr>
|
|
<tr><td>8</td> <td>green</td></tr>
|
|
<tr><td>A</td> <td>cyan</td></tr>
|
|
<tr><td>C</td> <td>yellow</td></tr>
|
|
<tr><td>E</td> <td>white</td></tr>
|
|
</tbody></table>
|
|
</blockquote>
|
|
<p>
|
|
There is a trap here: the manual is the same for NTSC, PAL, & SECAM.
|
|
This means that the descriptions for black & white must jive between NTSC
|
|
& PAL. If you make major changes to PAL black & white to achieve good
|
|
SECAM color, NTSC black & white must be made similar.
|
|
</p><p>
|
|
2. PAL sounds work fine on SECAM with one exception: when a sound is to
|
|
be turned off, it must be done by setting <a href="https://alienbill.com/2600/101/docs/stella.html#AUDV">AUDV0</a>/AUDV1 to 0, not by setting
|
|
<a href="https://alienbill.com/2600/101/docs/stella.html#AUDC">AUDC0</a>/AUDC1 to 0. Otherwise, you get an obnoxious background sound.
|
|
</p><p>
|
|
</p></blockquote>
|
|
<hr>
|
|
<a name="tia1a"></a>
|
|
<h3>TIA 1A - TELEVISION INTERFACE ADAPTOR (MODEL 1A)</h3>
|
|
<p>
|
|
<a name="tia1agen"></a>
|
|
GENERAL DESCRIPTION
|
|
</p><p>
|
|
</p><blockquote>
|
|
The TIA is an MOS integrated circuit designed to interface between an
|
|
eight (8) bit microprocessor and a television video modulator and to convert
|
|
eight (8) bit parallel data into serial outputs for the color, luminosity, and
|
|
composite sync required by a video modulator.
|
|
<p>
|
|
This circuit operates on a line by line basis, always outputting the same
|
|
information every television line unless new data is written into it by the
|
|
microprocessor.
|
|
</p><p>
|
|
A hardware sync counter produces horizontal sync timing independent of
|
|
the microprocessor. Vertical sync timing is supplied to this circuit by the
|
|
microprocessor and combined into composite sync.
|
|
</p><p>
|
|
Horizontal position counters are used to trigger the serial output of five (5)
|
|
horizontally movable objects; two players, two missiles and a ball. The
|
|
microprocessor can add or subtract from these position counters to move
|
|
these objects right or left.
|
|
</p><p>
|
|
The microprocessor determines all vertical position and motion by writing
|
|
zeros or ones into object registers before each appropriate horizontal line.
|
|
</p><p>
|
|
Walls, clouds and other seldom moved objects are produced by a low
|
|
resolution data register called the playfield register.
|
|
</p><p>
|
|
A fifteen (15) bit collision register detects all fifteen possible two object
|
|
collisions between these six (6) objects (five moveable and one playfield).
|
|
This collision register can be read and reset by the microprocessor. Six input
|
|
ports are also provided on this chip that can be read by the microprocessor.
|
|
These input ports and the collision register are the only chip addresses that
|
|
can be read by the microprocessor. All other addresses are write only.
|
|
</p><p>
|
|
Color luminosity registers are included that can be programmed by the
|
|
microprocessor with eight (8) luminosity and fifteen (15) color values. A
|
|
digital phase shifter is included on this chip to provide a single color output
|
|
with fifteen (15) phase angles.
|
|
</p><p>
|
|
Two (2) independent audio generating circuits are included, each with
|
|
programmable frequency, noise content, and volume control registers.
|
|
</p><p>
|
|
</p></blockquote>
|
|
<a name="tia1adet"></a>
|
|
DETAILED DESCRIPTION
|
|
<blockquote>
|
|
<p>
|
|
<a name="tia1a1"></a>
|
|
1. Data and addressing
|
|
</p><p>
|
|
</p><blockquote>
|
|
Registers on this chip are addressed by the microprocessor as part of its
|
|
overall RAM-ROM memory space. The attached table of read-write
|
|
addresses summarizes the addressable functions. There are no registers
|
|
that are both read and write. Some addresses however are both read and
|
|
write, with write data going into one register and read data returning from
|
|
a different register.
|
|
<p>
|
|
If the read-write line is low, the data bits indicated in this table will be
|
|
written into the addressed write location when the 02 clock goes from high
|
|
to low. Some registers are eight bits wide, some only one bit, and some
|
|
(strobes) have no bits, performing only control functions (such as resets)
|
|
when their address is written.
|
|
</p><p>
|
|
If the read-write line is high, the addressed location can be read by the
|
|
microprocessor on data lines 6 and 7 while the 02 clock is high.
|
|
</p><p>
|
|
The addresses given in the table refer only to the six (6) real address lines.
|
|
If any of the four (4) chip select lines are used for addressing, the addresses
|
|
must be modified accordingly.
|
|
</p><p>
|
|
</p></blockquote>
|
|
<a name="tia1a2"></a>
|
|
2. Synchronization
|
|
<blockquote>
|
|
<p>
|
|
A. Horizontal Timing
|
|
</p><blockquote>
|
|
A hardware counter on this chip produces all horizontal timing (such as
|
|
sync, blank, burst) independent of the microprocessor, This counter is
|
|
driven from an external 3.58 Mhz oscillator and has a total count of 228.
|
|
Blank is decoded as 68 counts and sync and color burst as 16 counts.
|
|
</blockquote>
|
|
<p>
|
|
B. Vertical Timing
|
|
</p><blockquote>
|
|
There are one bit, addressable registers on this chip for vertical sync and
|
|
vertical blank. The timing for these functions is established by the
|
|
microprocessor by writing zero or one into these bits. (<a href="https://alienbill.com/2600/101/docs/stella.html#VSYNC">VSYNC</a>, <a href="https://alienbill.com/2600/101/docs/stella.html#VBLANK">VBLANK</a> )
|
|
</blockquote>
|
|
<p>
|
|
C. Composite Sync
|
|
</p><blockquote>
|
|
Horizontal sync and the output of the vertical sync bit are combined
|
|
together to produce composite sync. This composite sync signal drives a
|
|
chip output pad to an external composite video resistor network.
|
|
</blockquote>
|
|
<p>
|
|
D. Microprocessor Synchronization
|
|
</p><blockquote>
|
|
The 3.58 MHz oscillator also clocks a divide by three counter on this chip
|
|
whose output (1.19 Mhz) is buffered to drive an output pad called 00. This
|
|
pad provides the input phase zero clock to the microprocessor which then
|
|
produces the system 02 clock (1.19 Mhz).
|
|
Software program loops require different lengths of time to run depending
|
|
on branch decisions made within the program. Additional synchronization
|
|
between the software and hardware. This is done with a one bit latch called
|
|
<a href="https://alienbill.com/2600/101/docs/stella.html#WSYNC">WSYNC</a> (wait for sync). When the microprocessor finishes a routine such
|
|
as loading registers for a horizontal line, or computing new vertical
|
|
locations during vertical blank, it can address WSYNC, setting this latch
|
|
high. When this latch is high, it drives an output pad to zero connected to
|
|
the microprocessor ready line (RDY). A zero on this line causes the
|
|
microprocessor to halt and wait. As shown in figure 2, WSYNC latch is
|
|
automatically reset to zero by the leading edge of the next horizontal blank
|
|
timing signal, releasing the RDY line, allowing the microprocessor to begin
|
|
its computation and register writing for this horizontal television line or
|
|
line pair.
|
|
<p>
|
|
</p></blockquote>
|
|
</blockquote>
|
|
<a name="tia1a3"></a>
|
|
3. Playfield graphics Register
|
|
<p>
|
|
</p><blockquote>
|
|
A. Description
|
|
<blockquote>
|
|
Objects such as walls, clouds, and score) which are not required to move, are
|
|
written into a 20 bit register called the playfield register. This register
|
|
(Figure 5) is loaded from the data bus by three separate write addresses
|
|
(<a href="https://alienbill.com/2600/101/docs/stella.html#PF">PF0</a>, PFl, PF2). Playfield may be loaded at any time. To clear the playfield,
|
|
zeros must be written into all three addresses.
|
|
<p>
|
|
</p></blockquote>
|
|
B. Normal Serial Output
|
|
<blockquote>
|
|
The playfield register is automatically scanned (and converted to serial
|
|
output) by a bi-directional shift register clocked at a rate which spreads the
|
|
twenty (20) bits out over the left half of a horizontal line. This scanning is
|
|
initiated by the end of horizontal blank (left edge of television screen).
|
|
Normally the same scan is then repeated, duplicating the same twenty (20)
|
|
bit sequence over the right half of the horizontal line.
|
|
<p>
|
|
</p></blockquote>
|
|
C. Reflected Serial Output
|
|
<blockquote>
|
|
A reflected playfield may be requested by writing a one into bit zero of the
|
|
playfield control register (<a href="https://alienbill.com/2600/101/docs/stella.html#CTRLPF">CTRLPF</a>). When this bit is true the scanning
|
|
shift register will scan the opposite direction during the right half of the
|
|
horizontal line, reversing the twenty (20) bit sequence.
|
|
<p>
|
|
</p></blockquote>
|
|
D. Timing Constraints
|
|
<blockquote>
|
|
Even though the playfield bytes (<a href="https://alienbill.com/2600/101/docs/stella.html#PF">PF0</a>, PFl, PF2) may be written to any time,
|
|
if one of them is changed while being serially scanned, part of the new value
|
|
may both show up on the television horizontal line.
|
|
<p>
|
|
</p></blockquote>
|
|
</blockquote>
|
|
<a name="tia1a4"></a>
|
|
4. Horizontal Position Counters
|
|
<blockquote>
|
|
<p>
|
|
A. Description
|
|
</p><blockquote>
|
|
The playfield is a fixed graphics register, always starting its serial output
|
|
when triggered by the beginning of each television line. This chip also
|
|
includes five "moveable" graphics registers, whose serial outputs are
|
|
triggered by five separate horizontal position counters every time these
|
|
counters pass through zero count. These position counters are clocked
|
|
continuously during the unblanked portion of every horizontal line and
|
|
their count length is exactly equal to the normal number of clocks supplied
|
|
to them during this time. They will therefore pass through zero at the same
|
|
time during each horizontal television line and the triggered outputs will
|
|
have no horizontal motion. A typical horizontal counter is shown in figure 4.
|
|
<p>
|
|
If extra clocks are supplied to these counters (or normal clocks suppressed)
|
|
the zero crossing time will shift and the object will have moved left (extra
|
|
clocks) or right (fewer clocks). Some position counters have extra decoders
|
|
(in addition to a zero decode) to trigger multiple copies of the same object
|
|
across a horizontal line.
|
|
</p><p>
|
|
All position counters can be reset to zero count by the microprocessor at any
|
|
time, by a write instruction to the reset addresses (<a href="https://alienbill.com/2600/101/docs/stella.html#RESBL">RESBL</a>, <a href="https://alienbill.com/2600/101/docs/stella.html#RESM">RESM0</a>, RESMl,
|
|
<a href="https://alienbill.com/2600/101/docs/stella.html#RESP">RESP0</a>, RESPl). If reset occurs during horizontal blank, the object will
|
|
appear at the left side of the television screen. Properly timed resets may
|
|
position an object at any horizontal location consistent with the
|
|
microprocessor cycle time.
|
|
</p><p>
|
|
</p></blockquote>
|
|
B. Ball position Counter
|
|
<blockquote>
|
|
The ball position counter has only the zero crossing decode and therefore
|
|
cannot trigger multiple copies of the ball graphics.
|
|
<p>
|
|
</p></blockquote>
|
|
C. Player Position Counters
|
|
<blockquote>
|
|
Each player position counter has three decodes in addition to the zero
|
|
crossing decode. These decodes are controlled by bits 0,1,2 of the number
|
|
size control registers (<a href="https://alienbill.com/2600/101/docs/stella.html#NUSIZ">NUSIZ0</a>, NUSIZ1), and trigger 1,2, or 3 copies of the
|
|
player (at various spacings) across a horizontal line as shown on page <a href="https://alienbill.com/2600/101/docs/stella.html#NUSIZ">___</a>.
|
|
These same control bits are used for the decodes on the missile position
|
|
counter, insuring an equal number of players and missiles.
|
|
</blockquote>
|
|
D. Missile Position Counters
|
|
<blockquote>
|
|
Missile position counters are identical to player position counters except
|
|
that they have another type of reset in addition to the previously discussed
|
|
horizontal position reset. These extra reset addresses (<a href="https://alienbill.com/2600/101/docs/stella.html#RESMP">RESMP0</a>, RESMP1)
|
|
write data bit 1 into a one bit register whose output is used to position the
|
|
missile (horizontally) directly on top of its corresponding player, and to
|
|
disable the missile serial output.
|
|
<p>
|
|
</p></blockquote>
|
|
</blockquote>
|
|
<a name="tia1a5"></a>
|
|
5. Horizontal Motion Registers
|
|
<p>
|
|
</p><blockquote>
|
|
A. General Description
|
|
<blockquote>
|
|
There are five write only registers on this chip that contain the horizontal
|
|
motion values for each of the five moving objects. A typical horizontal
|
|
motion register is shown in figure 4 . The data bus (bits 4 through 7) is
|
|
written into these addresses (<a href="https://alienbill.com/2600/101/docs/stella.html#HMP">HMP0</a>, HMPl, <a href="https://alienbill.com/2600/101/docs/stella.html#HMM">HMM0</a>, HMMl, <a href="https://alienbill.com/2600/101/docs/stella.html#HMBL">HMBL</a>) to load
|
|
these registers with motion values. These registers supply extra (or fewer)
|
|
clocks to the horizontal position counters only when commanded to do so by
|
|
an <a href="https://alienbill.com/2600/101/docs/stella.html#HMOVE">HMOVE</a> address from the microprocessor. These registers may all be
|
|
cleared to zero (no motion) simultaneously by an <a href="https://alienbill.com/2600/101/docs/stella.html#HMCLR">HMCLR</a> command from
|
|
the microprocessor, or individually by loading zeros into each register.
|
|
These registers are each four bits in length and may be loaded with positive
|
|
(left motion), negative (right motion) or zero (no motion) values. Negative
|
|
values are represented in twos complement format.
|
|
<p>
|
|
</p></blockquote>
|
|
B. Timing constraints
|
|
<blockquote>
|
|
These registers may be loaded or cleared at almost any time. The motion
|
|
values they contain will be used only when an HMOVE command is
|
|
addressed, and then all five motion values will be used simultaneously into
|
|
all five horizontal position counters once. The only timing constraint on this
|
|
operation involves the <a href="https://alienbill.com/2600/101/docs/stella.html#HMOVE">HMOVE</a> command. The HMOVE command must be
|
|
located in the microprocessor program immediately after a wait for sync
|
|
(WSYNC) command. This assures that the HMOVE operation begins at the
|
|
leading edge of horizontal blank, and has the full blank time to supply extra
|
|
or fewer clocks to the horizontal position counters. These registers should
|
|
not be modified for at least 24 Computer cycles after the HMOVE command.
|
|
<p>
|
|
</p></blockquote>
|
|
</blockquote>
|
|
<a name="tia1a6"></a>
|
|
6. Moving Object Graphics Registers
|
|
<p>
|
|
</p><blockquote>
|
|
A. General Description
|
|
<blockquote>
|
|
There are five graphics registers for moving objects on this chip. These
|
|
graphics registers are loaded (written) in parallel by the microprocessor and
|
|
like the playfield register are scanned and converted to serial output.
|
|
Unlike the playfield register, which is always scanned beginning at the left
|
|
side of each horizontal line, moving object graphics registers are scanned
|
|
only when triggered by a start decode from their horizontal position
|
|
counter. A typical graphics register is shown in figure 4 .
|
|
<p>
|
|
</p></blockquote>
|
|
B. Missile Graphics
|
|
<blockquote>
|
|
The graphics registers for both missiles are identical and very simple. They
|
|
each consist of a one bit register called missile enable (<a href="https://alienbill.com/2600/101/docs/stella.html#ENAM">ENAM0</a>, ENAM1).
|
|
This graphics bit is scanned (outputted) only when triggered by its
|
|
corresponding position counter. There are control bits (bits 4, 5, of <a href="https://alienbill.com/2600/101/docs/stella.html#NUSIZ">NUSIZ0</a>,
|
|
NUSIZ1) that can stretch this single graphics bit out over widths of 1, 2, 4,
|
|
or 8 clocks of horizontal line time. (A full line is 160 clocks).
|
|
<p>
|
|
</p></blockquote>
|
|
C. Player Graphics
|
|
<blockquote>
|
|
The graphics registers for both players are identical and are rather complex.
|
|
They each consist of eight bit parallel registers (<a href="https://alienbill.com/2600/101/docs/stella.html#GRP">GRP0</a>, GRP1) and a bi-
|
|
directional parallel to serial scan counter that converts the parallel data
|
|
into serial output. A one bit control register (<a href="https://alienbill.com/2600/101/docs/stella.html#REFP">REFP0</a>, REFP1) determines
|
|
the direction (reflection) of the parallel to serial scan, outputing either D7
|
|
through D0, or D0 though D7. This allows reflection (horizontal flipping) of
|
|
player serial graphics data without having to flip the microprocessor data.
|
|
<p>
|
|
The clock into the scan counter can be controlled (three bits of <a href="https://alienbill.com/2600/101/docs/stella.html#NUSIZ">NUSIZ0</a> and
|
|
NUSIZ1) to slow the scan rate and stretch the eight bits of serial graphics
|
|
out over widths of 8, 16, or 32 clocks of horizontal line time. These same
|
|
control bits are used in the player-missile motion counters to control
|
|
multiple copies, so only three player widths ( scan
|
|
rates) are available.
|
|
</p><p>
|
|
</p></blockquote>
|
|
D. Vertical Delay
|
|
<blockquote>
|
|
Each of the player graphics registers actually consists of two 8 bit parallel
|
|
registers. The first (<a href="https://alienbill.com/2600/101/docs/stella.html#GRP">GRP0</a>, GRP1) is loaded (written) from the
|
|
microprocessor 8 bit data bus. The second is automatically loaded from the
|
|
output of the first. The reason for this is a complex subject called vertical
|
|
delay. A large amount of microprocessor time is required to generate
|
|
player, missile and playfield graphics (table look up, masking, comparisons,
|
|
etc.) and load these into this chip's registers. For most game programs this
|
|
time is just too large to fit into one horizontal line time. In fact for most
|
|
games it will barely fit into two line times (127 microseconds). Therefore,
|
|
individual graphics registers are loaded (written) every two lines, and used
|
|
twice for serial output between loads. This type of programing will
|
|
obviously limit the vertical height resolution of objects to multiples of two
|
|
lines. It also will limit the resolution of vertical motion to two lines jumps.
|
|
Nothing can be done about the vertical height resolution; however, vertical
|
|
motion can be resolved to a single line by addition of a second graphics
|
|
register that is automatically parallel loaded from the output of the first,
|
|
one line time after the first was loaded from the data bus. This second
|
|
graphics register output is therefore always delayed vertically by one line. A
|
|
control bit called vertical delay (<a href="https://alienbill.com/2600/101/docs/stella.html#VDELP">VDEL0</a>, VDEL1) selects which of these two
|
|
registers is to be used for serial output. If this control bit is set by the
|
|
microprocessor between picture frames, the object will be moved down
|
|
(delayed) by one line during the next frame. In most programming
|
|
applications player 0 graphics and player 1 graphics are loaded (written)
|
|
alternately, during the blank time just prior to each line as shown in (figure
|
|
1). Since <a href="https://alienbill.com/2600/101/docs/stella.html#GRP">GRP0</a> and GRP1 addresses from the microprocessor alternate,
|
|
they are delayed by one line from each other. The GRP0 address decode can
|
|
therefore be used to load the delayed graphics register for player 1, and
|
|
GRP1 likewise to load the delayed graphics register for player 0. The two
|
|
vertical delay bits (<a href="https://alienbill.com/2600/101/docs/stella.html#VDELP">VDEL0</a>, VDELl) then select delayed or undelayed
|
|
registers for player 0 and player 1 as serial outputs.
|
|
<p>
|
|
</p></blockquote>
|
|
E. Ball Graphics
|
|
<blockquote>
|
|
The ball graphics register is almost identical to the missile graphics
|
|
register. It also consists of a single enable bit (<a href="https://alienbill.com/2600/101/docs/stella.html#ENABL">ENABL</a>) whose output is
|
|
triggered by the ball position counter. It also has two control bits (bits 4, 5
|
|
of <a href="https://alienbill.com/2600/101/docs/stella.html#CTRLPF">CTRLPF</a>) that can stretch this single graphics bit out over widths of 1, 2,
|
|
4, or 8 clocks of horizontal line time. Unlike the missile graphics; however,
|
|
the ball graphics register has capability for vertical delay similar to the
|
|
player graphics. A second graphics (enable) bit is alternately loaded from
|
|
the output of the first, one line after the first was loaded from the data bus.
|
|
A ball vertical delay bit (<a href="https://alienbill.com/2600/101/docs/stella.html#VDELBL">VDELBL</a>) selects which of these two graphics bits
|
|
is used for the ball serial output. The first graphics bit (ENABL) should be
|
|
loaded during the same horizontal blank time as player 0 (<a href="https://alienbill.com/2600/101/docs/stella.html#GRP">GRP0</a>), because
|
|
GRP1 is used to load the second enable bit from the output of the first on
|
|
alternate lines.
|
|
<p>
|
|
</p></blockquote>
|
|
</blockquote>
|
|
<a name="tia1a7"></a>
|
|
7. Collision Detection Latches
|
|
<p>
|
|
</p><blockquote>
|
|
A. Definitions
|
|
<blockquote>
|
|
The serial outputs from all the graphics registers represent real time
|
|
horizontal location of objects on the television screen. If any of these outputs
|
|
occur at the same time, they will overlap (collide) on the screen. There are
|
|
six objects generated on this chip (five moving and playfield) allowing
|
|
fifteen possible two object collisions. These overlaps (collisions) are detected
|
|
by fifteen "and" gates whenever they occur, and are stored in fifteen
|
|
individual latch register bits, as shown in figure 6.
|
|
<p>
|
|
</p></blockquote>
|
|
B. Reading Collision
|
|
<blockquote>
|
|
The microprocessor can read these fifteen collision bits on data lines 6 and 7
|
|
by addressing them two at a time. This could be done at any time but is
|
|
usually done between frames (during vertical blank) after all possible
|
|
collisions have serially occurred.
|
|
<p>
|
|
</p></blockquote>
|
|
C. Reset
|
|
<blockquote>
|
|
All collision bits are reset simultaneously by the microprocessor using the
|
|
reset address <a href="https://alienbill.com/2600/101/docs/stella.html#CXCLR">CXCLR</a>. This is usually done near the end of vertical blank,
|
|
after collisions have been tested.
|
|
<p>
|
|
</p></blockquote>
|
|
</blockquote>
|
|
<p>
|
|
<a name="tia1a8"></a>
|
|
8. Input ports
|
|
</p><p>
|
|
</p><blockquote>
|
|
A. General Description
|
|
<blockquote>
|
|
There are 6 input ports on this chip whose logic state may be read on data
|
|
line 7 with read addresses <a href="https://alienbill.com/2600/101/docs/stella.html#INPT">INPT0</a> through INPT5. These 6 ports are
|
|
divided into two types, "dumped" and "latched". See Figure 8.
|
|
<p>
|
|
</p></blockquote>
|
|
B. Dumped Input Ports (I0 through I3)
|
|
<blockquote>
|
|
These 4 input ports are normally used to read paddle position from an
|
|
external potentiometer-capacitor circuit. In order to discharge these
|
|
capacitors each of these input ports has a large transistor, which may be
|
|
turned on (grounding the input ports) by writing into bit 7 of the register
|
|
<a href="https://alienbill.com/2600/101/docs/stella.html#VBLANK">VBLANK</a>. When this control bit is cleared the potentiometers begin to
|
|
recharge the capacitors and the microprocessor measures the time required
|
|
to detect a logic 1 at each input port.
|
|
<p>
|
|
As long as bit 7 of register VBLANK is zero, these four ports are general
|
|
purpose high impedance input ports. When this bit is a 1 these ports are
|
|
grounded.
|
|
</p><p>
|
|
</p></blockquote>
|
|
C. Latched Input ports (I4, I5)
|
|
<blockquote>
|
|
These two input ports have latches which can be enabled or disabled by
|
|
writing into bit 6 of register VBLANK.
|
|
<p>
|
|
When disabled, these latches are removed from the circuit completely and
|
|
these ports become two general purpose input ports, whose present logic
|
|
state can be read directly by the microprocessor.
|
|
</p><p>
|
|
When enabled, these latches will store negative (zero logic level) signals
|
|
appearing on these two input ports, and the input port addresses will read
|
|
the latches instead of the input ports.
|
|
</p><p>
|
|
When first enabled these latches will remain positive as long as the input
|
|
ports remain positive (logic one). A zero input port signal will clear a latch
|
|
value to zero, where it will remain (even after the port returns positive)
|
|
until disabled. Both latches may be simultaneously disabled by writing a
|
|
zero into bit 6 of register <a href="https://alienbill.com/2600/101/docs/stella.html#VBLANK">VBLANK</a>.
|
|
</p><p>
|
|
</p></blockquote>
|
|
</blockquote>
|
|
<a name="tia1a8.5"></a>
|
|
8.5 Priority Encoder
|
|
<p>
|
|
</p><blockquote>
|
|
A. Purpose
|
|
<blockquote>
|
|
As discussed in the section on collisions, simultaneous serial outputs from
|
|
the graphics registers represent overlap on the television screen. In order to
|
|
have color-luminosity values assigned to individual objects it is necessary to
|
|
establish priorities between objects when overlapped. The priority encoder
|
|
is shown in figure 3.
|
|
<p>
|
|
</p></blockquote>
|
|
B. Priority Assignment
|
|
<blockquote>
|
|
The lack of any objects results in a color-lum value called the background.
|
|
The background (BK) has lowest priority and only appears when no objects
|
|
are outputing. In order to simplify the logic, each missile is given the same
|
|
color-lum value and priority as its corresponding player (P0, M0) and the
|
|
ball is given the same color-lum value and priority as the playfield (PF, BL).
|
|
<p>
|
|
The following table illustrates the normal priority assignment:
|
|
</p><p>
|
|
</p><blockquote>
|
|
<table border="1">
|
|
<tbody><tr><td>Highest Priority</td><td> P0, M0</td></tr>
|
|
<tr><td>Second Highest</td><td> P1, M1</td></tr>
|
|
<tr><td>Third Highest</td><td> PF, BL</td></tr>
|
|
<tr><td>Lowest Priority</td><td> BK</td></tr>
|
|
</tbody></table>
|
|
</blockquote>
|
|
<p>
|
|
Objects with higher priority will appear to move in front of objects with
|
|
lower priority. Players will therefore move in front of playfield (clouds,
|
|
walls, etc.).
|
|
</p><p>
|
|
</p></blockquote>
|
|
C. Priority Control
|
|
<blockquote>
|
|
There are two playfield control bits that affect priority, one called playfield
|
|
priority (PFP) (bit 2 of <a href="https://alienbill.com/2600/101/docs/stella.html#CTRLPF">CTRLPF</a>) and one called score (bit 1 of CTRLPF).
|
|
When a one is written into the PFP bit the priority assignment is modified
|
|
as shown below.
|
|
<p>
|
|
</p><blockquote>
|
|
<table border="1">
|
|
<tbody><tr><td>Highest Priority</td><td> PF, BL</td></tr>
|
|
<tr><td>Second Highest</td><td> P0, M0</td></tr>
|
|
<tr><td>Third Highest</td><td> P1, M1</td></tr>
|
|
<tr><td>Lowest Priority</td><td> BK</td></tr>
|
|
</tbody></table>
|
|
</blockquote>
|
|
<p>
|
|
Players will then move behind playfield (clouds, wall, etc.). When a one is
|
|
written into the score control bit, the playfield is forced to take the color-lum
|
|
of player 0 in the left half of the screen and player 1 in the right half of the
|
|
screen. This is used when displaying score and identifies the score with the
|
|
correct player. The priority encoder produces 4 register select lines shown
|
|
in figure 3) that are mutually exclusive. These 4 lines select either
|
|
background, player 0, player 1 or playfield, and only one of them can be
|
|
true at a time.
|
|
</p><p>
|
|
</p></blockquote>
|
|
</blockquote>
|
|
<a name="tia1a9"></a>
|
|
9. Color Luminance Registers
|
|
<p>
|
|
</p><blockquote>
|
|
A. Description
|
|
<blockquote>
|
|
There are four registers (shown in figure 3) that contain color-lum codes.
|
|
Four bits of color code and three its of luminance code may be written into
|
|
each of these registers (<a href="https://alienbill.com/2600/101/docs/stella.html#COLUP">COLUP0</a>, COLUP1, COLUPF, COLUBK) by the
|
|
microprocessor at any time. These codes (representing 16 color values and 8
|
|
luminance values) are given in the Detailed Address List.
|
|
<p>
|
|
</p></blockquote>
|
|
B. Multiplexing
|
|
<blockquote>
|
|
The serial graphics output from all six objects is examined by the priority
|
|
encoder which activates one of the four select lines into a 4 x 7 multiplexer.
|
|
This multiplexer (shown in figure 3) then selects one of the four color-lum
|
|
registers as a 7 line output. Three of these lines are binary coded
|
|
luminosity and go directly to chip output pads. The other four lines go to the
|
|
color phase shifter.
|
|
<p>
|
|
</p></blockquote>
|
|
</blockquote>
|
|
<a name="tia1a10"></a>
|
|
10. Color Phase Shifter
|
|
<p>
|
|
</p><blockquote>
|
|
This portion of the chip (shown in figure 3) produces a reference color
|
|
output (color burst) during horizontal blank and then during the unblanked
|
|
portion of the line it produces a color output shifted in phase with respect to
|
|
the color burst. The amount of phase shift determines the color and is
|
|
selected by the four color code lines from the Color-lum multiplexer. Binary
|
|
code 0 selects no color. Code 1 selects gold (same phase as color burst).
|
|
Codes 2 (0010) through 15 (1111) shift the phase from zero through almost
|
|
360 degrees allowing selection of 15 total colors around the television color
|
|
wheel.
|
|
<p>
|
|
</p></blockquote>
|
|
<a name="tia1a11"></a>
|
|
11. Audio Circuits
|
|
<p>
|
|
</p><blockquote>
|
|
Two audio circuits are incorporated on this chip. They are identical and
|
|
completely independent, although their outputs could be combined
|
|
externally into one speaker. Each audio circuit consists of parts described
|
|
below, and in figure 7.
|
|
<p>
|
|
A. Frequency Select
|
|
</p><blockquote>
|
|
Clock pulses (at approximately 30 KHz) from the horizontal sync counter
|
|
pass through a divide by N circuit which is controlled by the output code
|
|
from a five bit frequency register (<a href="https://alienbill.com/2600/101/docs/stella.html#AUDF">AUDF</a>). This register can be loaded
|
|
(written) by the microprocessor at any time, and causes the 30 KHz clocks
|
|
to be divided by 1 (code 00000) through 32 (code 11111). This produces
|
|
pulses that are digitally adjustable from approximately 30 KHz to 1 KHz
|
|
and are used to clock the noise-tone generator.
|
|
</blockquote>
|
|
B. Noise-Tone Generator
|
|
<blockquote>
|
|
This circuit contains a nine bit shift counter which may be controlled by the
|
|
output code from a four bit audio control register(<a href="https://alienbill.com/2600/101/docs/stella.html#AUDC">AUDC</a>), and is clocked by
|
|
the frequency select circuit. The control register can be loaded by the
|
|
microprocessor at any time, and selects different shift counter feedback taps
|
|
and count lengths to produce a variety of noise and tone qualities.
|
|
<p>
|
|
</p></blockquote>
|
|
C. Volume Select
|
|
<blockquote>
|
|
The shift counter output is used to drive the audio output pad through four
|
|
driver transistors that are graduated in size. Each transistor is twice as
|
|
large as the previous one and is enable by one bit from the audio volume
|
|
register (<a href="https://alienbill.com/2600/101/docs/stella.html#AUDV">AUDV</a>). This audio volume register may be loaded by the
|
|
microprocessor at any time. As binary codes 0 through 15 are loaded, the
|
|
pad drive transistors are enabled in a binary sequence. The shift counter
|
|
output therefore can pull down on the audio output pad with 16 selectable
|
|
impedance levels.
|
|
</blockquote>
|
|
</blockquote>
|
|
<p>
|
|
</p><hr>
|
|
<p>
|
|
<a href="https://alienbill.com/2600/101/docs/figure1.gif">Figure 1. Vertical Delay</a></p><p>
|
|
<a href="https://alienbill.com/2600/101/docs/figure2.gif">Figure 2. Synchronization<br>Figure 3. Color-Luminance</a></p><p>
|
|
<a href="https://alienbill.com/2600/101/docs/figure4.gif">Figure 4. Typical Horizontal Motion Circuit</a></p><p>
|
|
<a href="https://alienbill.com/2600/101/docs/figure5.gif">Figure 5. Playfield Graphics</a></p><p>
|
|
<a href="https://alienbill.com/2600/101/docs/figure6.gif">Figure 6. Collision Detection</a></p><p>
|
|
<a href="https://alienbill.com/2600/101/docs/figure7.gif">Figure 7. Audio Circuit</a></p><p>
|
|
<a href="https://alienbill.com/2600/101/docs/figure8.gif">Figure 8. Input Ports</a></p><p>
|
|
<a href="https://alienbill.com/2600/101/docs/figure9.gif">Figure 9. Game System</a></p><p>
|
|
</p><p>
|
|
</p><hr>
|
|
<p>
|
|
<a name="W"></a>
|
|
</p><h3>Write Address Detailed Functions</h3>
|
|
<p>
|
|
<a name="WSYNC"></a>
|
|
WSYNC (wait for sync)
|
|
</p><blockquote>
|
|
This address halts microprocessor by clearing RDY latch to zero. RDY is set true again
|
|
by the leading edge of horizontal blank.
|
|
<p>
|
|
Data bits not used
|
|
</p></blockquote>
|
|
<a name="RSYNC"></a>
|
|
RSYNC (reset sync)
|
|
<blockquote>
|
|
This address resets the horizontal sync counter to define the beginning of horizontal
|
|
blank time, and is used in chip testing.
|
|
<p>
|
|
Data bits not used.
|
|
</p></blockquote>
|
|
<a name="VSYNC"></a>
|
|
VSYNC
|
|
<blockquote>
|
|
This address controls vertical sync time by writing D1 into the VSYNC latch
|
|
<blockquote>
|
|
<table border="1">
|
|
<tbody><tr><td colspan="2">D1</td></tr>
|
|
<tr><td>0</td><td>Stop vertical sync</td></tr>
|
|
<tr><td>1</td><td>Start vertical sync</td></tr>
|
|
</tbody></table>
|
|
</blockquote>
|
|
</blockquote>
|
|
<a name="VBLANK"></a>
|
|
VBLANK
|
|
<blockquote>
|
|
This address controls vertical blank and the latches and dumping transistors on the input
|
|
ports by writing into bits D7, D6 and D1 of the VBLANK register.
|
|
<blockquote>
|
|
<table border="1">
|
|
<tbody><tr><td>Data Bit</td><td>Value</td><td>Effect</td></tr>
|
|
<tr><td rowspan="2">D1</td><td>0</td><td>Stop vert. blank</td></tr>
|
|
<tr><td>1</td><td>Start vert. blank</td></tr>
|
|
<tr><td rowspan="2">D6</td><td>0</td><td>Disable INPT4, INPT5 latches</td></tr>
|
|
<tr><td>1</td><td>Enable INPT4, INPT5 latches</td></tr>
|
|
<tr><td rowspan="2">D7</td><td>0</td><td>Remove INPT1,2,3,6 dump path to ground</td></tr>
|
|
<tr><td>1</td><td>Dump INPT1,2,3,6 to ground</td></tr>
|
|
</tbody></table>
|
|
Note : Disable latches (D6 = 0) also resets latches to logic true
|
|
</blockquote>
|
|
</blockquote>
|
|
<a name="PJ"></a>
|
|
PF0 (PF1, PF2)
|
|
<blockquote>
|
|
These addresses are used to write into playfield registers
|
|
<blockquote>
|
|
<table border="1">
|
|
<tbody><tr><td>PF0</td><td>D7</td><td>D6</td><td>D5</td><td>D4</td><td colspan="4">(not used)</td></tr>
|
|
<tr><td>PF1</td><td>D7</td><td>D6</td><td>D5</td><td>D4</td><td>D3</td><td>D2</td><td>D1</td><td>D0</td></tr>
|
|
<tr><td>PF2</td><td>D7</td><td>D6</td><td>D5</td><td>D4</td><td>D3</td><td>D2</td><td>D1</td><td>D0</td></tr>
|
|
</tbody></table>
|
|
</blockquote>
|
|
</blockquote>
|
|
<a name="PLAYFIELD"></a>
|
|
PLAYFIELD REGISTERS SERIAL OUTPUT
|
|
<blockquote>
|
|
<table border="1">
|
|
<tbody><tr><td colspan="6">1 horizontal line ( 160 clocks)</td><td>Playfield Reflect Control</td></tr>
|
|
<tr><td>4..7</td><td> 7......0</td><td> 0......7</td><td> 4..7</td><td> 7......0</td><td> 0......7</td><td rowspan="3"> REF = 0</td></tr>
|
|
<tr><td>PF0</td><td>PF1</td><td>PF2</td><td>PF0</td><td>PF1</td><td>PF2</td></tr>
|
|
<tr><td colspan="6" align="center">center</td></tr>
|
|
</tbody></table>
|
|
<table border="1">
|
|
<tbody><tr><td>4..7</td><td> 7......0</td><td> 0......7</td><td> 7......0</td><td> 0......7</td><td> 7..4</td><td rowspan="2"> REF = 1</td></tr>
|
|
<tr><td>PF0</td><td> PF1</td><td> PF2</td><td> PF2</td><td> PF1</td><td> PF0</td></tr>
|
|
</tbody></table>
|
|
<p>
|
|
each bit = 4 clocks
|
|
</p></blockquote>
|
|
<a name="CTRLPF"></a>
|
|
CTRLPF
|
|
<blockquote>
|
|
This address is used to write into the playfield control register
|
|
(a logic 1 causes action as described below)
|
|
<blockquote>
|
|
<table border="1">
|
|
<tbody><tr><td>D0</td><td>REF (reflect playfield)</td></tr>
|
|
<tr><td>D1</td><td>SCORE (left half of playfield gets color of player 0, right half gets color of player</td></tr>
|
|
<tr><td>D2</td><td>PFP (playfield gets priority over players so they can move behind the playfield)</td></tr>
|
|
<tr><td>D4</td><td rowspan="2">Ball Size (see next table)</td></tr>
|
|
<tr><td>D5</td></tr>
|
|
</tbody></table>
|
|
<p>
|
|
|
|
D4 & D5 = BALL SIZE
|
|
<table border="1">
|
|
<tbody><tr><td>D5</td><td>D4</td><td>Width</td></tr>
|
|
<tr><td>0</td><td>0</td><td>1 clock</td></tr>
|
|
<tr><td>0</td><td>1</td><td>2 clocks</td></tr>
|
|
<tr><td>1</td><td>0</td><td>4 clocks</td></tr>
|
|
<tr><td>1</td><td>1</td><td>8 clocks</td></tr>
|
|
</tbody></table>
|
|
</p></blockquote>
|
|
</blockquote>
|
|
<a name="NUSIZ"></a>
|
|
NUSIZ0 (NUSIZ1)
|
|
<blockquote>
|
|
These addresses control the number and size of players and missiles.
|
|
<blockquote>
|
|
Missile Size
|
|
<table border="1">
|
|
<tbody><tr><td>D5</td><td>D4</td><td>Width</td></tr>
|
|
<tr><td>0</td><td>0</td><td>1 clock</td></tr>
|
|
<tr><td>0</td><td>1</td><td>2 clocks</td></tr>
|
|
<tr><td>1</td><td>0</td><td>4 clocks</td></tr>
|
|
<tr><td>1</td><td>1</td><td>8 clocks</td></tr>
|
|
</tbody></table>
|
|
<p>
|
|
Player-Missile number & player size
|
|
<table border="1">
|
|
<tbody><tr><td>D2</td><td>D1</td><td>D0</td><td colspan="9">1/2 television line (80 clocks)<br>8 clocks per square</td><td>Description</td></tr>
|
|
<tr><td>0</td><td>0</td><td>0</td>
|
|
<td width="20">X</td>
|
|
<td width="20"> </td>
|
|
<td width="20"> </td>
|
|
<td width="20"> </td>
|
|
<td width="20"> </td>
|
|
<td width="20"> </td>
|
|
<td width="20"> </td>
|
|
<td width="20"> </td>
|
|
<td width="20"> </td>
|
|
<td>one copy</td></tr>
|
|
<tr><td>0</td><td>0</td><td>1</td>
|
|
<td width="20">X</td>
|
|
<td width="20"> </td>
|
|
<td width="20">X</td>
|
|
<td width="20"> </td>
|
|
<td width="20"> </td>
|
|
<td width="20"> </td>
|
|
<td width="20"> </td>
|
|
<td width="20"> </td>
|
|
<td width="20"> </td>
|
|
<td>two copies - close</td></tr>
|
|
<tr><td>0</td><td>1</td><td>0</td>
|
|
<td>X</td>
|
|
<td width="20"> </td>
|
|
<td width="20"> </td>
|
|
<td width="20"> </td>
|
|
<td width="20">X</td>
|
|
<td width="20"> </td>
|
|
<td width="20"> </td>
|
|
<td width="20"> </td>
|
|
<td width="20"> </td>
|
|
<td>two copies - med</td></tr>
|
|
<tr><td>0</td><td>1</td><td>1</td>
|
|
<td width="20">X</td>
|
|
<td width="20"> </td>
|
|
<td width="20">X</td>
|
|
<td width="20"> </td>
|
|
<td width="20">X</td>
|
|
<td width="20"> </td>
|
|
<td width="20"> </td>
|
|
<td width="20"> </td>
|
|
<td width="20"> </td>
|
|
<td>three copies - close</td></tr>
|
|
<tr><td>1</td><td>0</td><td>0</td>
|
|
<td width="20">X</td>
|
|
<td width="20"> </td>
|
|
<td width="20"> </td>
|
|
<td width="20"> </td>
|
|
<td width="20"> </td>
|
|
<td width="20"> </td>
|
|
<td width="20"> </td>
|
|
<td width="20"> </td>
|
|
<td width="20">X</td>
|
|
<td>two copies - wide</td></tr>
|
|
<tr><td>1</td><td>0</td><td>1</td>
|
|
|
|
<td width="20">X</td>
|
|
<td width="20">X</td>
|
|
<td width="20"> </td>
|
|
<td width="20"> </td>
|
|
<td width="20"> </td>
|
|
<td width="20"> </td>
|
|
<td width="20"> </td>
|
|
<td width="20"> </td>
|
|
<td width="20"> </td>
|
|
<td width="20">double size player</td></tr>
|
|
<tr><td>1</td><td>1</td><td>0</td>
|
|
|
|
<td width="20">X</td>
|
|
<td width="20"> </td>
|
|
<td width="20"> </td>
|
|
<td width="20"> </td>
|
|
<td width="20">X</td>
|
|
<td width="20"> </td>
|
|
<td width="20"> </td>
|
|
<td width="20"> </td>
|
|
<td width="20">X</td>
|
|
<td>3 copies medium</td></tr>
|
|
<tr><td>1</td><td>1</td><td>1</td>
|
|
|
|
<td width="20">X</td>
|
|
<td width="20">X</td>
|
|
<td width="20">X</td>
|
|
<td width="20">X</td>
|
|
<td width="20"> </td>
|
|
<td width="20"> </td>
|
|
<td width="20"> </td>
|
|
<td width="20"> </td>
|
|
<td width="20"> </td>
|
|
<td>quad sized player</td></tr>
|
|
</tbody></table>
|
|
</p></blockquote>
|
|
</blockquote>
|
|
<a name="RESP"></a>
|
|
<a name="RESM"></a>
|
|
<a name="RESBL"></a>
|
|
RESP0 (RESP1, RESM0, RESM1, RESBL)
|
|
<blockquote>
|
|
These addresses are used to reset players, missiles and the ball. The object will begin its
|
|
serial graphics at the time of a horizontal line at which the reset address occurs.
|
|
<p>
|
|
No data bits are used
|
|
</p></blockquote>
|
|
<a name="RESMP"></a>
|
|
RESMP0 (RESMP1)
|
|
<blockquote>
|
|
These addresses are used to reset the horiz. location of a missile to the center of its
|
|
corresponding player. As long as this control bit is true (1) the missile will remain
|
|
locked to the center of its player and the missile graphics will be disabled. When a
|
|
zero is written into this location, the missile is enabled, and can be moved independently
|
|
from the player.
|
|
<p>
|
|
</p><blockquote>
|
|
D1 = RESMP (missile-player reset)
|
|
</blockquote>
|
|
</blockquote>
|
|
<a name="HMOVE"></a>
|
|
HMOVE
|
|
<blockquote>
|
|
This address causes the horizontal motion register values to be acted upon during the
|
|
horizontal blank time in which it occurs. It must occur at the beginning of horiz. blank in
|
|
order to allow time for generation of extra clock pulses into the horizontal position
|
|
counters if motion is desired this command must immediately follow a WSYNC
|
|
command in the program.
|
|
<p>
|
|
No data bits are used.
|
|
</p></blockquote>
|
|
<a name="HMCLR"></a>
|
|
HMCLR
|
|
<blockquote>
|
|
This address clears all horizontal motion registers to zero (no motion).
|
|
No data bits are used.
|
|
</blockquote>
|
|
<a name="HMP"></a>
|
|
<a name="HMM"></a>
|
|
<a name="HMBL"></a>
|
|
HMP0 (HMP1, HMM0, HMM1, HMBL)
|
|
<blockquote>
|
|
These addresses write data (horizontal motion values) into the horizontal motion
|
|
registers. These registers will cause horizontal motion only when commanded to do so
|
|
by the horiz. move command HMOVE.
|
|
The motion values are coded as shown below :
|
|
<blockquote>
|
|
<table border="1">
|
|
<tbody><tr><td>D7</td><td>D6</td><td>D5</td><td>D4</td><td>Clocks</td><td>Effect</td></tr>
|
|
<tr><td>0</td><td>1</td><td>1</td><td>1</td><td>+7</td><td rowspan="7">Move left indicated number of clocks</td></tr>
|
|
<tr><td>0</td><td>1</td><td>1</td><td>0</td><td>+6</td></tr>
|
|
<tr><td>0</td><td>1</td><td>0</td><td>1</td><td>+5</td></tr>
|
|
<tr><td>0</td><td>1</td><td>0</td><td>0</td><td>+4</td></tr>
|
|
<tr><td>0</td><td>0</td><td>1</td><td>1</td><td>+3</td></tr>
|
|
<tr><td>0</td><td>0</td><td>1</td><td>0</td><td>+2</td></tr>
|
|
<tr><td>0</td><td>0</td><td>0</td><td>1</td><td>+1</td></tr>
|
|
<tr><td>0</td><td>0</td><td>0</td><td>0</td><td>0</td><td>No Motion</td></tr>
|
|
<tr><td>1</td><td>1</td><td>1</td><td>1</td><td>-1</td><td rowspan="8">Move right indicated number of clocks</td></tr>
|
|
<tr><td>1</td><td>1</td><td>1</td><td>0</td><td>-2</td></tr>
|
|
<tr><td>1</td><td>1</td><td>0</td><td>1</td><td>-3</td></tr>
|
|
<tr><td>1</td><td>1</td><td>0</td><td>0</td><td>-4</td></tr>
|
|
<tr><td>1</td><td>0</td><td>1</td><td>1</td><td>-5</td></tr>
|
|
<tr><td>1</td><td>0</td><td>1</td><td>0</td><td>-6</td></tr>
|
|
<tr><td>1</td><td>0</td><td>0</td><td>1</td><td>-7</td></tr>
|
|
<tr><td>1</td><td>0</td><td>0</td><td>0</td><td>-8</td></tr>
|
|
</tbody></table>
|
|
</blockquote>
|
|
WARNING : These motion registers should not be modified during the 24 computer
|
|
cycles immediately following an HMOVE command. Unpredictable motion values may
|
|
result.
|
|
</blockquote>
|
|
<a name="ENAM"></a>
|
|
<a name="ENABL"></a>
|
|
ENAM0 (ENAM1, ENABL)
|
|
<blockquote>
|
|
These addresses write D1 into the 1 bit missile or ball graphics registers.
|
|
<blockquote>
|
|
<table border="1">
|
|
<tbody><tr><td colspan="2">D1</td></tr>
|
|
<tr><td>0</td><td>Disables object</td></tr>
|
|
<tr><td>1</td><td>Enables object</td></tr>
|
|
</tbody></table>
|
|
</blockquote>
|
|
</blockquote>
|
|
<a name="GRP"></a>
|
|
GRP0 (GRP1)
|
|
<blockquote>
|
|
These addresses write data into the player graphics registers.
|
|
<blockquote>
|
|
<table border="1">
|
|
<tbody><tr><td>D7</td><td>D6</td><td>D5</td><td>D4</td><td>D3</td><td>D2</td><td>D1</td><td>D0</td></tr>
|
|
<tr><td colspan="8">Graphics Data</td></tr>
|
|
</tbody></table>
|
|
</blockquote>
|
|
Note: serial output begins with D7, unless REFP0 (REFP1) = 1
|
|
</blockquote>
|
|
<a name="REFP"></a>
|
|
REFP0 (REFP1)
|
|
<blockquote>
|
|
These addesses write D3 into the 1 bit player reflect registers
|
|
<blockquote>
|
|
<table border="1">
|
|
<tbody><tr><td colspan="2">D3</td></tr>
|
|
<tr><td>0</td><td>no reflect, D7 of GRPx on left</td></tr>
|
|
<tr><td>1</td><td>reflect, D0 of GRPx on left</td></tr>
|
|
</tbody></table>
|
|
</blockquote>
|
|
</blockquote>
|
|
<a name="VDELP"></a>
|
|
<a name="VDELBL"></a>
|
|
VDELP0 (VDELP1, VDELBL)
|
|
<blockquote>
|
|
These addresses write D0 into the 1 bit vertical delay registers, to delay players or ball by
|
|
one vertical line.<p>
|
|
</p><blockquote>
|
|
<table border="1">
|
|
<tbody><tr><td colspan="2">D0</td></tr>
|
|
<tr><td>0</td><td>no delay</td></tr>
|
|
<tr><td>1</td><td>delay</td></tr>
|
|
</tbody></table>
|
|
</blockquote>
|
|
</blockquote>
|
|
<a name="CXCLR"></a>
|
|
CXCLR
|
|
<blockquote>
|
|
This adderess clears all collision latches to zero (no collision).
|
|
No data bits are used.
|
|
</blockquote>
|
|
<a name="COLUP"></a>
|
|
COLUP0 (COLUP1, COLUPF, COLUBK)
|
|
<blockquote>
|
|
These addresses write data into the player, playfield, and background color-luminance
|
|
registers
|
|
<p>
|
|
</p><blockquote>
|
|
<table border="1">
|
|
<tbody><tr><td>COLOR</td><td>D7</td><td>D6</td><td>D5</td><td>D4</td><td>D3</td><td>D2</td><td>D1</td><td>LUM</td></tr>
|
|
<tr><td>grey - gold</td><td>0</td><td>0</td><td>0</td><td>0</td><td>0</td><td>0</td><td>0</td><td>black</td></tr>
|
|
<tr><td> </td><td>0</td><td>0</td><td>0</td><td>1</td><td>0</td><td>0</td><td>1</td><td>dark grey</td></tr>
|
|
<tr><td>orange, brt-org</td><td>0</td><td>0</td><td>1</td><td>0</td><td>0</td><td>1</td><td>0</td></tr>
|
|
<tr><td> </td><td>0</td><td>0</td><td>1</td><td>1</td><td>0</td><td>1</td><td>1</td><td>grey</td></tr>
|
|
<tr><td>pink - purple</td><td>0</td><td>1</td><td>0</td><td>0</td><td>1</td><td>0</td><td>0</td></tr>
|
|
<tr><td> </td><td>0</td><td>1</td><td>0</td><td>1</td><td>1</td><td>0</td><td>1</td></tr>
|
|
<tr><td>purp-blue, blue</td><td>0</td><td>1</td><td>1</td><td>0</td><td>1</td><td>1</td><td>0</td><td>light grey</td></tr>
|
|
<tr><td> </td><td>0</td><td>1</td><td>1</td><td>1</td><td>1</td><td>1</td><td>1</td><td>white</td></tr>
|
|
<tr><td>blue - lt. blue</td><td>1</td><td>0</td><td>0</td><td>0</td></tr>
|
|
<tr><td> </td><td>1</td><td>0</td><td>0</td><td>1</td></tr>
|
|
<tr><td>torq. - grn. blue</td><td>1</td><td>0</td><td>1</td><td>0</td></tr>
|
|
<tr><td> </td><td>1</td><td>0</td><td>1</td><td>1</td></tr>
|
|
<tr><td>grn. - yel. grn.</td><td>1</td><td>1</td><td>0</td><td>0</td></tr>
|
|
<tr><td> </td><td>1</td><td>1</td><td>0</td><td>1</td></tr>
|
|
<tr><td>org. grn - lt org.</td><td>1</td><td>1</td><td>1</td><td>0</td></tr>
|
|
<tr><td> </td><td>1</td><td>1</td><td>1</td><td>1</td></tr>
|
|
</tbody></table>
|
|
</blockquote>
|
|
</blockquote>
|
|
<a name="AUDF"></a>
|
|
AUDF0 (AUDF1)
|
|
<blockquote>
|
|
These addresses write data into the audio frequency divider registers.
|
|
<p>
|
|
</p><blockquote>
|
|
<table border="1">
|
|
<tbody><tr><td>D4</td><td> D3</td><td> D2</td><td> D1</td><td> D0</td><td> 30KHz divided by</td></tr>
|
|
<tr><td>0</td><td>0</td><td>0</td><td>0</td><td>0</td><td>no division</td></tr>
|
|
<tr><td>0</td><td>0</td><td>0</td><td>0</td><td>1</td><td>divide by 2</td></tr>
|
|
<tr><td>0</td><td>0</td><td>0</td><td>1</td><td>0</td><td>divide by 3</td></tr>
|
|
<tr><td>...</td><td>...</td><td>...</td><td>...</td><td>...</td><td>...</td></tr>
|
|
<tr><td>1</td><td>1</td><td>1</td><td>1</td><td>0</td><td>divide by 31</td></tr>
|
|
<tr><td>1</td><td>1</td><td>1</td><td>1</td><td>1</td><td>divide by 32</td></tr>
|
|
</tbody></table>
|
|
</blockquote>
|
|
</blockquote>
|
|
<a name="AUDC"></a>
|
|
AUDC0 (AUDC1)
|
|
<blockquote>
|
|
These addresses write data into the audio control registers which control the noise
|
|
content and additional division of the audio output.
|
|
<p>
|
|
</p><blockquote>
|
|
<table border="1">
|
|
<tbody><tr><td>D3</td><td> D2</td><td> D1</td><td> D0</td><td> Type of noise or division</td></tr>
|
|
<tr><td>0</td><td>0</td><td>0</td><td>0</td><td>set to 1</td></tr>
|
|
<tr><td>0</td><td>0</td><td>0</td><td>1</td><td>4 bit poly</td></tr>
|
|
<tr><td>0</td><td>0</td><td>1</td><td>0</td><td>div 15 -> 4 bit poly</td></tr>
|
|
<tr><td>0</td><td>0</td><td>1</td><td>1</td><td>5 bit poly -> 4 bit poly</td></tr>
|
|
<tr><td>0</td><td>1</td><td>0</td><td>0</td><td>div 2 : pure tone</td></tr>
|
|
<tr><td>0</td><td>1</td><td>0</td><td>1</td><td>div 2 : pure tone</td></tr>
|
|
<tr><td>0</td><td>1</td><td>1</td><td>0</td><td>div 31 : pure tone</td></tr>
|
|
<tr><td>0</td><td>1</td><td>1</td><td>1</td><td>5 bit poly -> div 2</td></tr>
|
|
<tr><td>1</td><td>0</td><td>0</td><td>0</td><td>9 bit poly (white noise)</td></tr>
|
|
<tr><td>1</td><td>0</td><td>0</td><td>1</td><td>5 bit poly</td></tr>
|
|
<tr><td>1</td><td>0</td><td>1</td><td>0</td><td>div 31 : pure tone</td></tr>
|
|
<tr><td>1</td><td>0</td><td>1</td><td>1</td><td>set last 4 bits to 1</td></tr>
|
|
<tr><td>1</td><td>1</td><td>0</td><td>0</td><td>div 6 : pure tone</td></tr>
|
|
<tr><td>1</td><td>1</td><td>0</td><td>1</td><td>div 6 : pure tone</td></tr>
|
|
<tr><td>1</td><td>1</td><td>1</td><td>0</td><td>div 93 : pure tone</td></tr>
|
|
<tr><td>1</td><td>1</td><td>1</td><td>1</td><td>5 bit poly div 6</td></tr>
|
|
</tbody></table>
|
|
</blockquote>
|
|
</blockquote>
|
|
<a name="AUDV"></a>
|
|
AUDV0 (AUDV1)
|
|
<blockquote>
|
|
These addresses write data into the audio volume registers which set the pull down
|
|
impedance driving the audio output pads.
|
|
<p>
|
|
</p><blockquote>
|
|
<table border="1">
|
|
<tbody><tr><td>D3</td><td> D2</td><td> D1</td><td> D0</td><td> Audio Output Pull down current</td></tr>
|
|
<tr><td>0</td><td> 0</td><td> 0</td><td> 0</td><td> No output current</td></tr>
|
|
<tr><td>0</td><td> 0</td><td> 0</td><td> 1</td><td> lowest</td></tr>
|
|
<tr><td>0</td><td> 0</td><td> 1</td><td> 0</td></tr>
|
|
<tr><td>...</td><td> ...</td><td> ...</td><td> ...</td></tr>
|
|
<tr><td>1</td><td> 1</td><td> 1</td><td> 0</td></tr>
|
|
<tr><td>1</td><td> 1</td><td> 1</td><td> 1</td><td> highest</td></tr>
|
|
</tbody></table>
|
|
</blockquote>
|
|
</blockquote>
|
|
<p>
|
|
</p><hr>
|
|
<p>
|
|
<a name="wsummary"></a>
|
|
</p><h3>TIA WRITE ADDRESS SUMMARY</h3>
|
|
<blockquote>
|
|
<table border="1">
|
|
<tbody><tr><td>6-bit Address</td><td>Address Name</td><td>7</td><td>6</td><td>5</td><td>4</td><td>3</td><td>2</td><td>1</td><td>0</td><td>Function</td></tr>
|
|
<tr><td>00</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#VSYNC">VSYNC</a> </td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td>1</td><td>.</td><td> vertical sync set-clear</td></tr>
|
|
<tr><td>01</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#VBLANK">VBLANK</a> </td><td>1</td><td>1</td><td>.</td><td>.</td><td>.</td><td>.</td><td>1</td><td>.</td><td> vertical blank set-clear</td></tr>
|
|
<tr><td>02</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#WSYNC">WSYNC</a> </td><td colspan="8" align="center">strobe</td><td> wait for leading edge of horizontal blank</td></tr>
|
|
<tr><td>03</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#RSYNC">RSYNC</a> </td><td colspan="8" align="center">strobe</td><td> reset horizontal sync counter</td></tr>
|
|
<tr><td>04</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#NUSIZ">NUSIZ0</a> </td><td>.</td><td>.</td><td>1</td><td>1</td><td>1</td><td>1</td><td>1</td><td>1</td><td> number-size player-missile 0</td></tr>
|
|
<tr><td>05</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#NUSIZ">NUSIZ1</a> </td><td>.</td><td>.</td><td>1</td><td>1</td><td>1</td><td>1</td><td>1</td><td>1</td><td> number-size player-missile 1</td></tr>
|
|
<tr><td>06</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#COLUP">COLUP0</a> </td><td>1</td><td>1</td><td>1</td><td>1</td><td>1</td><td>1</td><td>1</td><td>.</td><td> color-lum player 0</td></tr>
|
|
<tr><td>07</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#COLUP">COLUP1</a> </td><td>1</td><td>1</td><td>1</td><td>1</td><td>1</td><td>1</td><td>1</td><td>.</td><td> color-lum player 1</td></tr>
|
|
<tr><td>08</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#COLUP">COLUPF</a> </td><td>1</td><td>1</td><td>1</td><td>1</td><td>1</td><td>1</td><td>1</td><td>.</td><td> color-lum playfield</td></tr>
|
|
<tr><td>09</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#COLUP">COLUBK</a> </td><td>1</td><td>1</td><td>1</td><td>1</td><td>1</td><td>1</td><td>1</td><td>.</td><td> color-lum background</td></tr>
|
|
<tr><td>0A</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#CTRLPF">CTRLPF</a> </td><td>.</td><td>.</td><td>1</td><td>1</td><td>.</td><td>1</td><td>1</td><td>1</td><td> control playfield ball size & collisions</td></tr>
|
|
<tr><td>0B</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#REFP">REFP0</a> </td><td>.</td><td>.</td><td>.</td><td>.</td><td>1</td><td>.</td><td>.</td><td>.</td><td> reflect player 0</td></tr>
|
|
<tr><td>0C</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#REFP">REFP1</a> </td><td>.</td><td>.</td><td>.</td><td>.</td><td>1</td><td>.</td><td>.</td><td>.</td><td> reflect player 1</td></tr>
|
|
<tr><td>0D</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#PF">PF0</a> </td><td>1</td><td>1</td><td>1</td><td>1</td><td>.</td><td>.</td><td>.</td><td>.</td><td> playfield register byte 0</td></tr>
|
|
<tr><td>0E</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#PF">PF1</a> </td><td>1</td><td>1</td><td>1</td><td>1</td><td>1</td><td>1</td><td>1</td><td>1</td><td> playfield register byte 1</td></tr>
|
|
<tr><td>0F</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#PF">PF2</a> </td><td>1</td><td>1</td><td>1</td><td>1</td><td>1</td><td>1</td><td>1</td><td>1</td><td> playfield register byte 2</td></tr>
|
|
<tr><td>10</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#RESP">RESP0</a> </td><td colspan="8" align="center">strobe</td><td> reset player 0</td></tr>
|
|
<tr><td>11</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#RESP">RESP1</a> </td><td colspan="8" align="center">strobe</td><td> reset player 1</td></tr>
|
|
<tr><td>12</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#RESM">RESM0</a> </td><td colspan="8" align="center">strobe</td><td> reset missile 0</td></tr>
|
|
<tr><td>13</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#RESM">RESM1</a> </td><td colspan="8" align="center">strobe</td><td> reset missile 1</td></tr>
|
|
<tr><td>14</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#RESBL">RESBL</a> </td><td colspan="8" align="center">strobe</td><td> reset ball</td></tr>
|
|
<tr><td>15</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#AUDC">AUDC0</a> </td><td>.</td><td>.</td><td>.</td><td>.</td><td>1</td><td>1</td><td>1</td><td>1</td><td> audio control 0</td></tr>
|
|
<tr><td>16</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#AUDC">AUDC1</a> </td><td>.</td><td>.</td><td>.</td><td>1</td><td>1</td><td>1</td><td>1</td><td>1</td><td> audio control 1</td></tr>
|
|
<tr><td>17</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#AUDF">AUDF0</a> </td><td>.</td><td>.</td><td>.</td><td>1</td><td>1</td><td>1</td><td>1</td><td>1</td><td> audio frequency 0</td></tr>
|
|
<tr><td>18</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#AUDF">AUDF1</a> </td><td>.</td><td>.</td><td>.</td><td>.</td><td>1</td><td>1</td><td>1</td><td>1</td><td> audio frequency 1</td></tr>
|
|
<tr><td>19</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#AUDV">AUDV0</a> </td><td>.</td><td>.</td><td>.</td><td>.</td><td>1</td><td>1</td><td>1</td><td>1</td><td> audio volume 0</td></tr>
|
|
<tr><td>1A</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#AUDV">AUDV1</a> </td><td>.</td><td>.</td><td>.</td><td>.</td><td>1</td><td>1</td><td>1</td><td>1</td><td> audio volume 1</td></tr>
|
|
<tr><td>1B</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#GRP">GRP0</a> </td><td>1</td><td>1</td><td>1</td><td>1</td><td>1</td><td>1</td><td>1</td><td>1</td><td> graphics player 0</td></tr>
|
|
<tr><td>1C</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#GRP">GRP1</a> </td><td>1</td><td>1</td><td>1</td><td>1</td><td>1</td><td>1</td><td>1</td><td>1</td><td> graphics player 1</td></tr>
|
|
<tr><td>1D</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#ENAM">ENAM0</a> </td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td>1</td><td>.</td><td> graphics (enable) missile 0</td></tr>
|
|
<tr><td>1E</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#ENAM">ENAM1</a> </td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td>1</td><td>.</td><td> graphics (enable) missile 1</td></tr>
|
|
<tr><td>1F</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#ENABL">ENABL</a> </td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td>1</td><td>.</td><td> graphics (enable) ball</td></tr>
|
|
<tr><td>20</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#HMP">HMP0</a> </td><td>1</td><td>1</td><td>1</td><td>1</td><td>.</td><td>.</td><td>.</td><td>.</td><td> horizontal motion player 0</td></tr>
|
|
<tr><td>21</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#HMP">HMP1</a> </td><td>1</td><td>1</td><td>1</td><td>1</td><td>.</td><td>.</td><td>.</td><td>.</td><td> horizontal motion player 1</td></tr>
|
|
<tr><td>22</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#HMM">HMM0</a> </td><td>1</td><td>1</td><td>1</td><td>1</td><td>.</td><td>.</td><td>.</td><td>.</td><td> horizontal motion missile 0</td></tr>
|
|
<tr><td>23</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#HMM">HMM1</a> </td><td>1</td><td>1</td><td>1</td><td>1</td><td>.</td><td>.</td><td>.</td><td>.</td><td> horizontal motion missile 1</td></tr>
|
|
<tr><td>24</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#HMBL">HMBL</a> </td><td>1</td><td>1</td><td>1</td><td>1</td><td>.</td><td>.</td><td>.</td><td>.</td><td> horizontal motion ball</td></tr>
|
|
<tr><td>25</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#VDELP">VDELP0</a> </td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td>1</td><td> vertical delay player 0</td></tr>
|
|
<tr><td>26</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#VDELP">VDELP1</a> </td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td>1</td><td> vertical delay player 1</td></tr>
|
|
<tr><td>27</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#VDELBL">VDELBL</a> </td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td>1</td><td> vertical delay ball</td></tr>
|
|
<tr><td>28</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#RESMP">RESMP0</a> </td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td>1</td><td>.</td><td> reset missile 0 to player 0</td></tr>
|
|
<tr><td>29</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#RESMP">RESMP1</a> </td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td>1</td><td>.</td><td> reset missile 1 to player 1</td></tr>
|
|
<tr><td>2A</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#HMOVE">HMOVE</a> </td><td colspan="8" align="center">strobe</td><td> apply horizontal motion</td></tr>
|
|
<tr><td>2B</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#HMCLR">HMCLR</a> </td><td colspan="8" align="center">strobe</td><td> clear horizontal motion registers</td></tr>
|
|
<tr><td>2C</td><td><a href="https://alienbill.com/2600/101/docs/stella.html#CXCLR">CXCLR</a> </td><td colspan="8" align="center">strobe</td><td> clear collision latches</td></tr>
|
|
</tbody></table>
|
|
</blockquote>
|
|
<p>
|
|
</p><hr>
|
|
<p>
|
|
<a name="rsummary"></a>
|
|
</p><h3>TIA READ ADDRESS SUMMARY</h3>
|
|
|
|
<blockquote>
|
|
<table border="1">
|
|
<tbody><tr><td>6-bit Address</td><td>Address Name </td><td>7</td><td>6</td><td>5</td><td>4</td><td>3</td><td>2</td><td>1</td><td>0</td><td> Function</td><td>D7</td><td>D6</td></tr>
|
|
<tr><td>0</td><td>CXM0P </td><td>1</td><td>1</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td> read collision </td><td>M0 P1 </td><td>M0 P0</td></tr>
|
|
<tr><td>1</td><td>CXM1P </td><td>1</td><td>1</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td> read collision </td><td>M1 P0 </td><td>M1 P1</td></tr>
|
|
<tr><td>2</td><td>CXP0FB </td><td>1</td><td>1</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td> read collision </td><td>P0 PF </td><td>P0 BL</td></tr>
|
|
<tr><td>3</td><td>CXP1FB </td><td>1</td><td>1</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td> read collision </td><td>P1 PF </td><td>P1 BL</td></tr>
|
|
<tr><td>4</td><td>CXM0FB </td><td>1</td><td>1</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td> read collision </td><td>M0 PF </td><td>M0 BL</td></tr>
|
|
<tr><td>5</td><td>CXM1FB </td><td>1</td><td>1</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td> read collision </td><td>M1 PF </td><td>M1 BL</td></tr>
|
|
<tr><td>6</td><td>CXBLPF </td><td>1</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td> read collision </td><td>BL PF </td><td>unused</td></tr>
|
|
<tr><td>7</td><td>CXPPMM </td><td>1</td><td>1</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td> read collision </td><td>P0 P1 </td><td>M0 M1</td></tr>
|
|
<tr><td>8</td><td>INPT0 </td><td>1</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td colspan="3"> read pot port</td></tr>
|
|
<tr><td>9</td><td>INPT1 </td><td>1</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td colspan="3"> read pot port</td></tr>
|
|
<tr><td>A</td><td>INPT2 </td><td>1</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td colspan="3"> read pot port</td></tr>
|
|
<tr><td>B</td><td>INPT3 </td><td>1</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td colspan="3"> read pot port</td></tr>
|
|
<tr><td>C</td><td>INPT4 </td><td>1</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td colspan="3"> read input</td></tr>
|
|
<tr><td>D</td><td>INPT5 </td><td>1</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td>.</td><td colspan="3"> read input</td></tr>
|
|
</tbody></table>
|
|
Note : I0, I2, I2, I3 can be grounded
|
|
under software control.
|
|
I4, I5 can be converted to latched
|
|
inputs under software control
|
|
</blockquote>
|
|
<p>
|
|
<i>(For PIA I/O addresses, see section <a href="https://alienbill.com/2600/101/docs/stella.html#pia6.0">6,0</a> --BW)</i>
|
|
</p><p>
|
|
</p><hr>
|
|
<p>
|
|
<a name="ednotes"></a>
|
|
Editor's Notes</p><p>
|
|
<i>(This section is *not* part of the manual, so you can ignore it if
|
|
you want! --BW)</i>
|
|
</p><blockquote>
|
|
I did this HTML version of the Stella Programming Guide for a couple of
|
|
reasons:
|
|
<ul>
|
|
<li>
|
|
The existing PDF version is great, but I really hate having to use a PDF
|
|
reader to read it. HTML is (supposedly) cross-platform, and since I already
|
|
keep 10-15 browser windows open at any given time, I'd rather use the same
|
|
GUI for reading the Stella docs as I do for everything else that's graphical.
|
|
</li><li>
|
|
The existing plain-text version I found is ok, but it's missing all the
|
|
diagrams (of course), and some of the text formatting is a bit strange.
|
|
</li><li>
|
|
I tried numerous programs that claim to convert PDF (or PostScript) to HTML,
|
|
but they all produced ugly, unusable results.
|
|
</li><li>
|
|
I wanted internal links in the document, such as the table of contents. The
|
|
existing PDF version doesn't seem to have them. The next version of this
|
|
document will probably have links to external `how-to' docs, with code
|
|
snippets and such.
|
|
</li><li>
|
|
The Stella/Atari development community are some of the nicest people I've
|
|
ever met, and this is my attempt to give back to the community in some small
|
|
way.
|
|
</li><li>
|
|
Finally, I needed an excuse to procrastinate... my poor 2600 game is in a
|
|
nasty state of disrepair, and I'm at the point where I'd be better starting
|
|
from scratch. Taking a break from 6502 asm and writing in a `language' like
|
|
HTML gives me a much-needed breather.
|
|
</li></ul>
|
|
<p>
|
|
The original PDF version has a few typos. I don't know if those are in the
|
|
original paper version, or mistakes in the transcription, but I fixed as many
|
|
of them as I could find (most of them were silly, like <i>it's</i> instead of
|
|
<i>its</i>, or <i>sidable</i> for <i>disable</i>). Also, I didn't try to
|
|
format the tables exactly as they appear in the PDF version, since HTML isn't
|
|
much good for that sort of thing anyway. I did my best to preserve the content,
|
|
but took a few liberties with the presentation.</p><p>
|
|
|
|
Although I have tried to avoid it, I'm sure I introduced a few errors and
|
|
typos of my own. If anybody spots one, let me know, and I'll fix it ASAP.</p><p>
|
|
|
|
As far as copyright goes, who knows what the official, legal status of the
|
|
Stella Programmer's Guide is? I sure don't. But this HTML version is free for
|
|
anyone to use and/or redistribute, as much as the original version is. If
|
|
you modify this version, I'd really appreciate it if you'd clearly mark your
|
|
new version as modified. Better yet, if you fix some of my mistakes, show me
|
|
what I did wrong so I can learn from them!</p><p>
|
|
|
|
I looked at this in Netscape 4.7, Opera 5.0b6, and Konqueror 2.1 on Linux, and IE 5.0 on Win98; it looks OK on all of them.
|
|
If you have any problems with the HTML formatting, please let me know. I tried to
|
|
use `bog standard' HTML as much as possible, so it should work OK on any
|
|
browser, on any OS, but if it doesn't, I'll fix it the best I am able.</p><p>
|
|
|
|
B. Watson<br>
|
|
atari@hardcoders.org<br>
|
|
09/15/2001<br>
|
|
|
|
</p></blockquote></blockquote></body></html> |