296 lines
12 KiB
HTML
296 lines
12 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
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<html>
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<head>
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<title>AppleWin Debugger Tutorial</title>
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<meta http-equiv="CONTENT-TYPE" content="text/html; charset=windows-1252">
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</head>
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<body style="DIRECTION: ltr" lang="en-US">
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<h2><a name="Symbols"></a>Symbols</h2>
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<p>
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When a programmer writes an assembly language program instead of directly referring to a memory address over and over again they use a <b>symbolic name</b> instead.
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For example, instead of always directly hard-coding $C000 everywhere to read the keyboard they would instead write:
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</p>
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<p><font color="#00b8ff"><font face="courier"><b><pre style="background: rgb(0,0,0) 0% 50%;">
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ORG $300
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KEYBOARD EQU $C000
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300:AD 00 C0 .1 LDA KEYBOARD
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303:10 FB BPL .1
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305:8D 00 04 STA $0400
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306:60 RTS
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</pre></b></font></font></p>
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<p>
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Let's try this out in the debugger. Make sure AppleWin is running. Press F2 (to reboot), then Ctrl-F2 (to break), and F7 (to enter the debugger.)
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If you don't want to type in the following hex code, you can select it, copy it (Ctrl-C), and paste it into the Debugger console (Ctrl-V).
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</p>
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<p><font color="#00b8ff"><font face="Courier"><b><pre style="BACKGROUND: rgb(0,0,0) 0% 50%;">
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300:AD 00 C0 10 FB 8D 00 04 60
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300L
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</pre></b></font></font></p>
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<p>
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Press F7 to exit the debugger, then type:
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</p>
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<p><font color="#00b8ff"><font face="Courier"><b><pre style="BACKGROUND: rgb(0,0,0) 0% 50%;">
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HOME:CALL 768
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</pre></b></font></font></p>
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<p>
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Press Enter. The emulated computer will wait for your to press a key and then echo it in the top left.
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</p>
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<p>
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When debugging assembly programs since you typically don't have the source file availabe you can tell the debugger how to interpret a memory address as a variable name or symbol.
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A <b>symbol</b> is the symbolic name and the address assigned to it.
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</p>
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<p>AppleWin supports loading of the assemblers ACME, and Merlin's symbol tables -- a collection of symbols, one per line, organized and collectively called a symbol table.
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The semi-colon is a comment-till-end-of-line. The file format per line is: <b>ADDRESS SYMBOL</b></p>
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<p>e.g.</p>
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<p><font color="#00b8ff"><font face="courier"><b><pre style="background: rgb(0,0,0) 0% 50%;">
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; IO Map
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C000 KEYBOARD
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</pre></b></font></font></p>
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<p>
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There are <b>9</b> symbol tables to help organize "modules"; each symbol table individually can be turned off/on independently.
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<pre>
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MAIN APPLE2E.SYM
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BASIC A2_BASIC.SYM
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ASM A2_ASM.SYM
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User1 A2_USER1.SYM
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User2 A2_USER2.SYM
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Src1 A2_SRC1.SYM
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Src2 A2_SRC2.SYM
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DOS33 A2_DOS33.SYM
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PRODOS A2_PRODOS.SYM
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</pre></p>
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<p>On startup the debugger reads 3 symbol tables by default: Main, Basic, User1.</p>
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</p>
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<p>Looking up symbols is easy. If you can't remember an address of a symbol,
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or the reversse -- can't remember the symbol for an address -- you can use the following symbol commands:
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(#### referes to either a hex address or a symbolic name)
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</p>
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<p><br>
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<br>
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</p>
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<table border="0" cellpadding="2" cellspacing="0" width="80%">
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<COLGROUP>
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<col width="64">
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<col width="192">
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<tbody>
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<tr bgcolor="#000000">
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<td bgcolor="#000000" width="25%">
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<p><font color="#ffffff"><b>Command</b></font></p>
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</td>
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<td bgcolor="#000000" width="75%">
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<p style="FONT-STYLE: normal"><font color="#ffffff"><b>Effect</b></font></p>
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</td>
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</tr>
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<tr bgcolor="#cccccc">
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<td width="25%">
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<p><font color="#000000"><font face="Courier"><b><span style="BACKGROUND: 0% 50%; ">SYM</span></b></font></font></p>
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</td>
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<td width="75%">
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<p><i><span style="BACKGROUND: 0% 50%; ">Display
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the number of symbols in the Main, User, and Source symbol tables.</span></i></p>
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</td>
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</tr>
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<tr bgcolor="#999999">
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<td width="25%">
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<p><font color="#000000"><font face="Courier"><b><span style="BACKGROUND: 0% 50%; ">SYM
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####</span></b></font></font></p>
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</td>
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<td width="75%">
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<p><i><span style="BACKGROUND: 0% 50%; ">Look-up
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the Symbol or Address, and display which Symbol Table it is in.</span></i></p>
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</td>
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</tr>
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<tr bgcolor="#cccccc">
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<td width="25%">
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<p><font color="#000000"><font face="Courier"><b><span style="BACKGROUND: 0% 50%; ">SYMUSER
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LOAD</span></b></font></font></p>
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</td>
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<td width="75%">
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<p><i><span style="BACKGROUND: 0% 50%; ">Reloads
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the User Symbol Table: <b>A2_USER1.SYM</b></span></i></p>
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</td>
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</tr>
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<tr bgcolor="#999999">
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<td width="25%">
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<p><font color="#000000"><font face="Courier"><b><span style="BACKGROUND: 0% 50%; ">SYMUSER
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CLEAR</span></b></font></font></p>
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</td>
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<td width="75%">
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<p><i><span style="BACKGROUND: 0% 50%;">Clears
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the User Symbol Table from RAM.</span></i></p>
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</td>
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</tr>
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<tr bgcolor="#cccccc">
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<td width="25%">
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<p><font color="#000000"><font face="Courier"><b><span style="BACKGROUND: 0% 50%; ">SYMMAIN
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####</span></b></font></font></p>
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</td>
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<td width="75%">
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<p><i><span style="BACKGROUND: 0% 50%; ">Look-up
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only in the Main symbol table.</span></i></p>
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</td>
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</tr>
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<tr bgcolor="#999999">
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<td width="25%">
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<p><font color="#000000"><font face="Courier"><b><span style="BACKGROUND: 0% 50%; ">SYMUSER
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####</span></b></font></font></p>
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</td>
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<td width="75%">
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<p><i><span style="BACKGROUND: 0% 50%; ">Look-up
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only in the User symbol table.</span></i></p>
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</td>
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</tr>
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<tr bgcolor="#cccccc">
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<td width="25%">
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<p><font color="#000000"><font face="Courier"><b><span style="BACKGROUND: 0% 50%; ">SYMSRC
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####</span></b></font></font></p>
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</td>
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<td width="75%">
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<p><i><span style="BACKGROUND: 0% 50%; ">Look-up
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only in the Source symbol table.</span></i></p>
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</td>
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</tr>
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<tr bgcolor="#999999">
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<td width="25%">
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<p><font color="#000000"><font face="Courier"><b><span style="BACKGROUND: 0% 50%; ">SYM
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name = ####</span></b></font></font></p>
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</td>
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<td width="75%">
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<p><i><span style="BACKGROUND: 0% 50%; ">Add
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(or update) a symbol in the User table with the new Address.</span></i></p>
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</td>
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</tr>
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<tr bgcolor="#cccccc">
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<td width="25%">
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<p><font color="#000000"><font face="Courier"><b><span style="BACKGROUND: 0% 50%; ">SYM
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! name</span></b></font></font></p>
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</td>
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<td width="75%">
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<p><i><span style="BACKGROUND: 0% 50%; ">Remove
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a symbol from the User table.</span></i></p>
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</td>
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</tr>
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<tr bgcolor="#999999">
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<td width="25%">
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<p><font color="#000000"><font face="Courier"><b><span style="BACKGROUND: 0% 50%; ">MEB
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symbol ##</span></b></font></font></p>
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</td>
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<td width="75%">
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<p><i>Set memory (at the symbol Address) to the 8-Bit (byte) Value.</i></p>
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</td>
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</tr>
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<tr bgcolor="#cccccc">
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<td width="25%">
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<p><font color="#000000"><font face="Courier"><b>MEW symbol ####</b></font></font></p>
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</td>
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<td width="75%">
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<p><i>Set memory (at the symbol Address) to the 16-Bit (word) Value.</i></p>
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</td>
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</tr>
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<tr bgcolor="#999999">
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<td width="25%">
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<p><font color="#000000"><font face="Courier"><b>E16 symbol ####</b></font></font></p>
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</td>
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<td width="75%">
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<p><i>Alias for EW.</i></p>
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</td>
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</tr>
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</tbody>
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</table>
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<p><br>
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<br>
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</p>
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<p><font size="4"><b>Examples</b>:</font></p>
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<table bgcolor="#000000" border="0" cellpadding="2" cellspacing="0" width="799">
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<COLGROUP>
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<col width="276">
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<col width="515">
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<tbody>
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<tr bgcolor="#00b8ff">
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<td bgcolor="#30c0ff" width="276">
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<p><font color="#000000"><b>Input</b></font></p>
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</td>
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<td bgcolor="#30c0ff" width="515">
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<p><font color="#000000"><b>Effect</b></font></p>
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</td>
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</tr>
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<tr bgcolor="#000000">
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<td width="276">
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<p><font color="#00b8ff"><font face="Courier"><b>SYM</b></font></font></p>
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</td>
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<td width="515">
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<p><font color="#ffffff"><i>Displays number of symbols in the Main, User, and Source
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tables.</i></font></p>
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</td>
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</tr>
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<tr bgcolor="#000000">
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<td width="276">
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<p><font color="#00b8ff"><font face="Courier"><b>SYMMAIN CLEAR</b></font></font></p>
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</td>
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<td width="515">
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<p><font color="#ffffff"><i>Clears the main symbol table!!</i></font></p>
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</td>
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</tr>
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<tr bgcolor="#000000">
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<td width="276">
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<p><font color="#00b8ff"><font face="Courier"><b>SYMMAIN LOAD APPLE2E.SYM</b></font></font></p>
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</td>
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<td width="515">
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<p><font color="#ffffff"><i>Reloads the main symbol table.</i></font></p>
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</td>
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</tr>
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<tr bgcolor="#000000">
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<td bgcolor="#000000" width="276">
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<p><font color="#00b8ff"><font face="Courier"><b>SYM FA62</b></font></font></p>
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</td>
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<td bgcolor="#000000" width="515">
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<p><font color="#ffffff"><i>Look up the Address $<b><font color="#ffff00">FA62</font></b> (RESET).</i></font></p>
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</td>
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</tr>
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<tr bgcolor="#000000">
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<td bgcolor="#000000" width="276">
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<p><font color="#00b8ff"><font face="Courier"><b><span style="BACKGROUND: rgb(0,0,0) 0% 50%; ">SYM
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HOME</span></b></font></font></p>
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</td>
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<td bgcolor="#000000" width="515">
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<p><font color="#ffffff"><i>Look up the Symbol Home ($<b><font color="#ffff00">FC58</font></b>).</i></font></p>
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</td>
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</tr>
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<tr bgcolor="#000000">
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<td bgcolor="#000000" width="276">
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<p><font color="#00b8ff"><font face="Courier"><b><span style="BACKGROUND: rgb(0,0,0) 0% 50%;">SYM
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LIFE = 300</span></b></font></font></p>
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</td>
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<td bgcolor="#000000" width="515">
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<p><font color="#ffffff"><i>Define a new user symbol, called <20>Life<66> at Address $0300.</i></font></p>
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</td>
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</tr>
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<tr bgcolor="#000000">
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<td bgcolor="#000000" width="276">
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<p><font color="#00b8ff"><font face="Courier"><b><span style="BACKGROUND: rgb(0,0,0) 0% 50%;">MEB
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LIFE 64</span></b></font></font></p>
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</td>
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<td bgcolor="#000000" width="515">
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<p><font color="#ffffff"><i>Set 8-Bit variable (@ $<b><font color="#ffff00">0300</font></b>)<29>Life<66>
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to 100 (decimal).</i></font></p>
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</td>
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</tr>
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<tr bgcolor="#000000">
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<td bgcolor="#000000" width="276">
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<p><font color="#00b8ff"><font face="courier"><b><span style="background: rgb(0,0,0) 0% 50%; ">MEW
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LIFE 3E8</span></b></font></font></p>
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</td>
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<td bgcolor="#000000" width="515">
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<p><font color="#ffffff"><i>Set 16-Bit variable (@ $<b><font color="#ffff00">0300</font></b>)<29>Life<66>
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to $3E8 = 1000 (decimal).</i></font></p>
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</td>
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</tr>
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</tbody>
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</table>
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<p>
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<br>
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</p>
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</body>
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</html>
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