mirror of
https://github.com/RevCurtisP/C02.git
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294 lines
13 KiB
NASM
294 lines
13 KiB
NASM
; c02 Program Initialization Code for Unexpanded VIC-20
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;System Specific ASCII Key Mappings
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DELKEY EQU $7F ;Delete/Backspace Key (Delete)
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ESCKEY EQU $03 ;Escape/Stop Key (RUN/STOP)
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RTNKEY EQU $0D ;Return/Enter Key (RETURN)
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;Zero Page Locations
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; EQU $00 ;USR JMP
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adray1 EQU $03 ;Vector: Convert Floating Point to Signed Integer
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adray2 EQU $05 ;Vector: Convert Integet to Floating Point
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charac EQU $07 ;Search Character for Scanning BASIC Text Input
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endchr EQU $08 ;Search Character for Statement Terminator or Quote
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trmpos EQU $09 ;Column Position of Cursor before Last SPC or TAB
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verckb EQU $0A ;Flag: Load or Verify (BASIC)
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count EQU $0B ;Index into Text Input Buffer/Number of Array Subscripts
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dimflg EQU $0C ;Flags for Routines that Locate or Build an Array
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valtyp EQU $0D ;Type of Data (String or Numeric)
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intflg EQU $0E ;Type of Numeric Data (Integer or Floating Point)
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garbfl EQU $0F ;Flag for LIST, Garbage Collection, and Program Terminators
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subflg EQU $10 ;Subscript Reference to Array or User Defined Function Call
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inpflg EQU $11 ;Is Data Input to GET, READ, or INPUT?
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tansgn EQU $12 ;Sign of Result of TAN or SIN Function
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channl EQU $13 ;Current I/O Channel (CMD Logical File) Number
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linnum EQU $14 ;Integer Line Number Value
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temppt EQU $16 ;Pointer to Next Availabale Space in Temporary String Stack
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lastpt EQU $17 ;Pointer to Address of Last String in Temporary String Stack
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tempst EQU $19 ;Descriptor Stack for Temporary Strings
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index EQU $22 ;Miscellaneous Temporary Pointers and Save Area
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; $24
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resho EQU $26 ;Floating Point Multiplication Work Area
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txttab EQU $2B ;Pointer to Start of BASIC Program Text
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vartab EQU $2D ;Pointer to Start of BASIC Variable Storage Area
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arytab EQU $2F ;Pointer to Start of BASIC Array Storage Area
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strend EQU $31 ;Pointer to Start of Free RAM
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fretop EQU $33 ;Pointer to Bottom of String Text Storage Area
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frespc EQU $35 ;Temporary Pointer for Strings
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memsiz EQU $37 ;Pointer to Highest Address Used by BASIC
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curlin EQU $39 ;Current BASIC Line Number
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oldlin EQU $3B ;Previous BASIC Line Number
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oldtxt EQU $3D ;Pointer to Address of Current BASIC Statement
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datlin EQU $3F ;Current DATA Line Number
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datptr EQU $41 ;Pointer to Address of Current DATA Item
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inpptr EQU $43 ;Pointer to Source of GET, READ, or INPUT Information
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varnam EQU $45 ;Current Variable Name
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varpnt EQU $47 ;Pointer to Current BASIC Variable Value
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forpnt EQU $49 ;Temporary Pointer to Index Variable Used by FOR
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opptr EQU $4B ;Math Operator Table Displacement
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opmask EQU $4D ;Mask for Comparison Operator
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defpnt EQU $4E ;Pointer to Current FN Descriptor
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dscpnt EQU $50 ;Temporary Pointer to Current String Descriptor
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; $52 ;current string length
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four6 EQU $53 ;Constant for Garbage Collection
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jmper EQU $54 ;Jump to Function Instruction
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; $57 ;BASIC Numeric Work Area
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fac1 EQU $61 ;Floating Point Accumulator #1
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facexp EQU $61 ;Floating Point Accumulator #1: Exponent
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facho EQU $62 ;Floating Point Accumulator #1: Mantissa
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facsgn EQU $66 ;Floating Point Accumulator #1: Sign
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sgnflg EQU $67 ;Number of Terms in Series Evaluation
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bits EQU $68 ;Floating Point Accumulator #1: Overflow Digit
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fac2 EQU $69 ;Floating Point Accumulator #2
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argexp EQU $69 ;Floating Point Accumulator #2: Exponent
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argho EQU $6E ;Floating Point Accumulator #2: Mantissa
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argsgn EQU $6F ;Floating Point Accumulator #2: Sign
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facov EQU $70 ;Low Order Mantissa Byte of Floating Point Accumulator #1
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fbufpt EQU $71 ;Series Evaluation Pointer
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chrget EQU $73 ;Subroutine: Get Next BASIC Text Character
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chrgot EQU $79 ;Entry Point: Get Current BASIC Text Character
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txtptr EQU $7A ;Pointer to Current BASIC Text Character
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pointb EQU $7C ;Entry Point: Test Character in Accumulator
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exit EQU $8A ;RTS at end of CHRGET, CHRGOT, and POINTB Routines
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rndx EQU $8B ;RND Function Seed Value
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status EQU $90 ;Kernal I/O Status Word
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stkey EQU $91 ;Flag: Was STOP Key Pressed
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svxt EQU $92 ;Timing Constant for Tape Reads
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verck EQU $93 ;Flag: Load or Verify (Kernal)
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c3po EQU $94 ;Flag: Serial Bus - Output Character was Buffered
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bsour EQU $95 ;Buffered Character for Serial Bus
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syno EQU $96 ;Cassette Block Synchronization Number
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xsav EQU $97 ;Temporary .X Register Save Area
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ldtnd EQU $98 ;Number of Open I/O Files, Index to End of File Tables
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dfltn EQU $99 ;Default Input Device (Set to 0 for Keyboard)
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dflto EQU $9A ;Default Output (CMD) Device (Set to 3 for Screen)
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prty EQU $9B ;Tape Character Parity
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dpsw EQU $9C ;Flag: Tape Byte Received
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msflg EQU $9D ;Flag: Kernal Message Control
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ptr1 EQU $9E ;Tape Pass 1 Error Log Index
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ptr2 EQU $9F ;Tape Pass 2 Error Log Correction Index
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time EQU $A0 ;Software Jiffy Clock
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; EQU $A3 ;Temporary Data Storage Area
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cntdn EQU $A5 ;Cassette Synchronization Character Countdown
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bufpnt EQU $A6 ;Count of Characters in Tape I/O Buffer
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inbit EQU $A7 ;RS-232 Input Bits/Tape I/O Miscellaneous Flag
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bitci EQU $A8 ;RS-232 Input Bit Count/Tape Error Flag
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rinone EQU $A9 ;RS-232 Flag: Check for Start Bit/Tape Character Type Flag
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ridata EQU $AA ;RS-232 Input Byte Buffer
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riprty EQU $AB ;RS-232 Input Parity/Cassette Leader Counter
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sal EQU $AC ;Pointer to Starting Address of Load/Screen Scrolling
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eal EQU $AE ;Pointer to Ending Address of Load (End of Program)
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cmp0 EQU $B0 ;Used to Determine Value of SVXT
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; EQU $B1 ;Used in Timing of Tape Reads
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tape1 EQU $B2 ;Pointer: Start of Tape Buffer
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bitts EQU $B4 ;RS-232 Output Bit Count/Tape Load Receive Flag
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nxtbit EQU $B5 ;RS-232 Next Bit to Send/Tape EOT Flag
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rodata EQU $B6 ;RS-232 Output Byte Buffer
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fnlen EQU $B7 ;Length of Current Filename
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la EQU $B8 ;Current Logical File Number
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sa EQU $B9 ;Current Secondary Address
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fa EQU $BA ;Current Device Number
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fnadr EQU $BB ;Pointer: Current Filename
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roprt EQU $BD ;RS-232 Output Parity/Tape Character Being Read or Sent
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fsblk EQU $BE ;Cassette Read/Write Block Count
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mych EQU $BF ;Tape Input Byte Buffer
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cas1 EQU $C0 ;Tape Motor Interlock
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stal EQU $C1 ;I/O Start Address
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memuss EQU $C3 ;Tape Load Temporary Address
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lste EQU $C5 ;Matrix Coordinate of Last Key Pressed
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ndx EQU $C6 ;Number of Characters in Keyboard Buffer
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rvs EQU $C7 ;Flag: Print Reverse Characters
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indx EQU $C8 ;Pointer: End of Logical Line for Input
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lxsp EQU $C9 ;Cursor X.Y Position at Start of Input
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sfdx EQU $CB ;Matrix Coordinate of Current Key Pressed
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blnsw EQU $CC ;Cursor Blink Enable
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blnct EQU $CD ;Timer Countdown to Blink Cursor
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gdbln EQU $CE ;Character Under Cursor
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blnon EQU $CF ;Flag: Was Last Cursor Blink On or Off
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crsw EQU $D0 ;Flag: Input from Keyboard or Screen
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pnt EQU $D1 ;Pointer to Address of Current Screen Line
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pntr EQU $D3 ;Cursor Column on Current Line
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qtsw EQU $D4 ;Flag: Editor in Quote Mode?
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lnmx EQU $D5 ;Maximum Length of Physical Screen Line
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tblx EQU $D6 ;Current Cursor Physical Line Number
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; EQU $D7 ;Temporary Storage for ASCII Value of Last Character Printed
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insrt EQU $D8 ;Insert Mode (Number of Inserts)
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ldtb1 EQU $D9 ;Screen Line Link Table
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user EQU $F3 ;Pointer to Address of Current Screen Color RAM Location
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keytab EQU $F5 ;Vector: Keyboard Decode Table
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ribuf EQU $F7 ;Pointer: RS-232 Input Buffer
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robuf EQU $F8 ;Pointer: RS-232 Output Buffer
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frekzp EQU $FB ;Four Free Bytes of Zero Page for User Programs
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baszpt EQU $FF ;BASIC Temporary Data for Floating Point to ASCII Conversion
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;Page 1 Locations
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bad EQU $0100 ;Tape Input Error Log
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; EQU $013F ;Microprocessor Stack
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;Basic and Kernal Working Storage
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buf EQU $0200 ;BASIC Line Editor Input Buffer
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lat EQU $0259 ;Kernal Table of Active Logical File Numbers
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fat EQU $0263 ;Kernal Table of Device Numbers for Each Logical File
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sat EQU $026D ;Kernal Table of Secondary Addressed for Each Logical File
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keyd EQU $0277 ;Keyboard Buffer (Queue)
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memstr EQU $0281 ;Pointer: Operating System Start of Memory
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memsiz EQU $0283 ;Pointer: Operating System End of Memory
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timout EQU $0285 ;Flag: Kernal Variable for IEEE Timeout
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color EQU $0286 ;Current Foreground Color Text
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gdcol EQU $0287 ;Color of Character Under Cursor
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hibase EQU $0288 ;Top Page of Screen Memory
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xmax EQU $0289 ;Maximum Keyboard Buffer Size
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rptflg EQU $028A ;Flag: Which Key Will Repeat?
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kount EQU $028B ;Counter for Timing Delay Between Key Repeats
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delay EQU $028C ;Counter for Timing Delay Until First Key Repeat Begins
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shflag EQU $028D ;Flag: SHIFT/CTRL/Logo Keypress
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lstshf EQU $028E ;Last Pattern SHIFT/CTRL/Logo Keypress
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keylog EQU $028F ;Vector to Keyboard Table Setup Routine
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mode EQU $0291 ;Flag: Change Character Sets with SHIFT/Logo Keypress
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autodn EQU $0292 ;Flag: Screen Scroll Enabled
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m51ctr EQU $0293 ;RS-232: Mock 6551 Control Register
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m51cdr EQU $0294 ;RS-232: Mock 6551 Command Register
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m51adj EQU $0295 ;RS-232: Non-Standard Bit Timing (Not Implemented)
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rsstat EQU $0297 ;RS-232: Mock 6551 Status Register
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bitnum EQU $0298 ;RS-232: Number of Bits Left to be Sent/Received
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baudof EQU $0299 ;RS-232: Time Required to Send a Bit
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ridbe EQU $029B ;RS-232: Index to End of Receive Buffer
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ridbs EQU $029C ;RS-232: Index to Start of Receive Buffer
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rodbs EQU $029D ;RS-232: Index to Start of Transmit Buffer
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rodbe EQU $029E ;RS-232: Index to End of Transmit Buffer
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irqtmp EQU $029F ;Save Area for IRQ Vector During Cassette I/O
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enabl EQU $02A1 ;RS-232 Interrupts Enabled
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; EQU $02A2 ;CIA #1 Control Register B Activity During Cassette I/O
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; EQU $02A3 ;Save Area for CIA #1 Interrupt Control Register
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; EQU $02A4 ;Save Area for CIA #1 Control Register A
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; EQU $02A5 ;Temporary Index to Next Line for Screen Scrolling
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; EQU $02A6 ;PAL/NTSC Flag
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; EQU $02A7 ;Unused
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; EQU $02C0 ;Sprite 11
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;BASIC Indirect Vector Table
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ierror EQU $0300 ;Vector to Print BASIC Error Message Routine
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imain EQU $0302 ;Vector to Main BASIC Program Loop
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icrnch EQU $0304 ;Vector to Crunch ASCII Keyword into Tokens
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iqplop EQU $0306 ;Vector to List BASIC Token as ASCII Text
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igone EQU $0308 ;Vector to Execute Next BASIC Token
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ieval EQU $030A ;Vector to Evaluate Single-Term Arithmetic Expression
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;Register Storage Area
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sareg EQU $030C ;Storage Area for .A Register (Accumulator)
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sxreg EQU $030D ;Storage Area for .X Index Register
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syreg EQU $030E ;Storage Area for .Y Index Register
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spreg EQU $030F ;Storage Area for .P (Status) Register
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;Miscellaneous Vectors
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usrpok EQU $0310 ;JMP Instruction for User Function
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usradd EQU $0311 ;Address of USR Routine
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; EQU $0313 ;Unused
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cinv EQU $0314 ;Vector to IRQ Interrupt Routine
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cbinv EQU $0316 ;Vector: BRK Instruction Interrupt
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nminv EQU $0318 ;Vector: Non-Maskabke Interrupt
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;Kernal Indirect Vectors
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iopen EQU $031A ;Vector to Kernal OPEN Routine
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iclose EQU $031C ;Vector to Kernal CLOSE Routine
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ichkin EQU $031E ;Vector to Kernal CHKIN Routine
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ickout EQU $0320 ;Vector to Kernal CKOUT Routine
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iclrch EQU $0322 ;Vector to Kernal CLRCHN Routine
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ibasin EQU $0324 ;Vector to Kernal CHRIN Routine
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ibsout EQU $0326 ;Vector to Kernal CHROUT Routine
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istop EQU $0328 ;Vector to Kernal STOP Routine
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igetin EQU $032A ;Vector to Kernal GETIN Routine
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iclall EQU $032C ;Vector to Kernal CLALL Routine
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usrcmd EQU $032E ;Vector to User Defined Command (Unused)
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iload EQU $0330 ;Vector to Kernal LOAD Routine
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isave EQU $0332 ;Vector to Kernal SAVE Routine
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; $0334 ;Unused
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tbuffer EQU $033C ;Cassette I/O Buffer
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; $03FC ;Unused
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vicscn EQU $0400 ;Video Screen Memory Area
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; $07F8 ;Sprite Shape Data Pointers
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; $0800 ;BASIC Program Text
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; $8000 ;Autostart ROM Cartridge
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vicclr EQU $D800 ;Color RAM
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;Kernal Routines
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chrin EQU $FFCF ;Input Character to Channel
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chrout EQU $FFD2 ;Output Character to Channel
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getin EQU $FFE4 ;Read Character from Keyboard Buffer
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;Machine Language Basic Stub
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ORG $1001 ;Start Directly Above Stack
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basic: DC $0C, $10 ; Pointer to Next Line (4109)
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DC $00, $00 ; Line Number (0)
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DC $9E ; SYS
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DC $20 ; ' '
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DC $34, $31, $31 ,$30 ; "4110"
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DC $00 ;End of Line Marker
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DC $00, $00 ;End of Basic Program
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JMP main ;Execute Program
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;Poll Keyboard for Character
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plkey EQU getin ;Read Character from Keyboard Buffer
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;Read Character from Console
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;Wait for Character from Console
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getkey: JSR plkey ;Poll Keyboard
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BEQ getkey ;If No Key, Loop
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RTS
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;Delete Previous Character
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delchr: RTS
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;Advance Character to Next line
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newlin: LDA #$0D ;Load C/R into Accumulator
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;Print Character to Console
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prchr EQU chrout ;
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;Print Byte as Two-Digit Hex Number to Console
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prbyte: PHA ;Save Accumulater
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LSR ;Shift Hi Nybble to Low Nybble
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LSR
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LSR
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LSR
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JSR prhex ; and Print it
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PLA ;Restore Accumulator
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; and fall into prhex
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;Print Low Nybble as Hex Digit to Console
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prhex: AND #$0F ;Strip High Nybble
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CMP #$0A ;If Low Nybble >= 10
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BCC prhexc ;
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ADC #$06 ; Convert ':' to 'A'...
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prhexc: ADC #$30 ;Convert to ASCII Character
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JMP prchr ;Print Hex Digit and Return
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exit: RTS ;Return to Monitor
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