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< title > AppleWin Debugger Tutorial< / title >
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< h2 > < a name = "Symbols" > < / a > Symbols< / h2 >
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< p >
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.
For example, instead of always directly hard-coding $C000 everywhere to read the keyboard they would instead write:
< p > < font color = "#00b8ff" > < font face = "courier" > < b > < pre style = "background: rgb(0,0,0) 0% 50%;" >
KEYBOARD EQU $C000
1 LDA KEYBOARD
BPL 1
< / pre > < / b > < / font > < / font > < / p >
< / p > 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.
A < b > symbol< / b > is the symbolic name and the address assigned to it.< / P >
< 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.
The semi-colon is a comment-till-end-of-line. The file format per line is: < b > ADDRESS SYMBOL< / b > < / p >
< p > e.g.
< p > < font color = "#00b8ff" > < font face = "courier" > < b > < pre style = "background: rgb(0,0,0) 0% 50%;" >
; IO Map
C000 KEYBOARD
< / pre > < / b > < / font > < / font > < / p >
< p > There are 9 symbol tables to help organize "modules"; each symbol table individually can be turned off/on independently.
< pre >
MAIN APPLE2E.SYM
BASIC A2_BASIC.SYM
ASM A2_ASM.SYM
User1 A2_USER1.SYM
User2 A2_USER2.SYM
Src1 A2_SRC1.SYM
Src2 A2_SRC2.SYM
DOS33 A2_DOS33.SYM
PRODOS A2_PRODOS.SYM
< / pre > < / p >
< p > On startup the debugger reads 3 symbol tables by default: Main, Basic, User1.< / p >
< / p >
< p > Looking up symbols is easy. If you can't remember an address of a symbol,
or the reversse -- can't remember the symbol for an address -- you can use the following symbol commands:
(#### referes to either a hex address or a symbolic name)
< / p >
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< p > < br >
< br >
< / p >
< table border = "0" cellpadding = "2" cellspacing = "0" width = "80%" >
< COLGROUP >
< col width = "64" >
< col width = "192" >
< tbody >
< tr bgcolor = "#000000" >
< td bgcolor = "#000000" width = "25%" >
< p > < font color = "#ffffff" > < b > Command< / b > < / font > < / p >
< / td >
< td bgcolor = "#000000" width = "75%" >
< p style = "FONT-STYLE: normal" > < font color = "#ffffff" > < b > Effect< / b > < / font > < / p >
< / td >
< / tr >
< tr bgcolor = "#cccccc" >
< td width = "25%" >
< p > < font color = "#000000" > < font face = "Courier" > < b > < span style = "BACKGROUND: 0% 50%; moz-background-clip: initial; moz-background-origin: initial; moz-background-inline-policy: initial" > SYM< / span > < / b > < / font > < / font > < / p >
< / td >
< td width = "75%" >
< p > < i > < span style = "BACKGROUND: 0% 50%; moz-background-clip: initial; moz-background-origin: initial; moz-background-inline-policy: initial" > Display
the number of symbols in the Main, User, and Source symbol tables.< / span > < / i > < / p >
< / td >
< / tr >
< tr bgcolor = "#999999" >
< td width = "25%" >
< p > < font color = "#000000" > < font face = "Courier" > < b > < span style = "BACKGROUND: 0% 50%; moz-background-clip: initial; moz-background-origin: initial; moz-background-inline-policy: initial" > SYM
####< / span > < / b > < / font > < / font > < / p >
< / td >
< td width = "75%" >
< p > < i > < span style = "BACKGROUND: 0% 50%; moz-background-clip: initial; moz-background-origin: initial; moz-background-inline-policy: initial" > Look-up
the Symbol or Address, and display which Symbol Table it is in.< / span > < / i > < / p >
< / td >
< / tr >
< tr bgcolor = "#cccccc" >
< 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 >
< / td >
< td width = "75%" >
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< p > < i > < span style = "BACKGROUND: 0% 50%; " > Reloads
the User Symbol Table: < b > A2_USER1.SYM< / b > < / span > < / i > < / p >
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< / td >
< / tr >
< tr bgcolor = "#999999" >
< 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 >
< / td >
< td width = "75%" >
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< p > < i > < span style = "BACKGROUND: 0% 50%;" > Clears
the User Symbol Table from RAM.< / span > < / i > < / p >
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< / td >
< / tr >
< tr bgcolor = "#cccccc" >
< td width = "25%" >
< p > < font color = "#000000" > < font face = "Courier" > < b > < span style = "BACKGROUND: 0% 50%; moz-background-clip: initial; moz-background-origin: initial; moz-background-inline-policy: initial" > SYMMAIN
####< / span > < / b > < / font > < / font > < / p >
< / td >
< td width = "75%" >
< p > < i > < span style = "BACKGROUND: 0% 50%; moz-background-clip: initial; moz-background-origin: initial; moz-background-inline-policy: initial" > Look-up
only in the Main symbol table.< / span > < / i > < / p >
< / td >
< / tr >
< tr bgcolor = "#999999" >
< td width = "25%" >
< p > < font color = "#000000" > < font face = "Courier" > < b > < span style = "BACKGROUND: 0% 50%; moz-background-clip: initial; moz-background-origin: initial; moz-background-inline-policy: initial" > SYMUSER
####< / span > < / b > < / font > < / font > < / p >
< / td >
< td width = "75%" >
< p > < i > < span style = "BACKGROUND: 0% 50%; moz-background-clip: initial; moz-background-origin: initial; moz-background-inline-policy: initial" > Look-up
only in the User symbol table.< / span > < / i > < / p >
< / td >
< / tr >
< tr bgcolor = "#cccccc" >
< td width = "25%" >
< p > < font color = "#000000" > < font face = "Courier" > < b > < span style = "BACKGROUND: 0% 50%; moz-background-clip: initial; moz-background-origin: initial; moz-background-inline-policy: initial" > SYMSRC
####< / span > < / b > < / font > < / font > < / p >
< / td >
< td width = "75%" >
< p > < i > < span style = "BACKGROUND: 0% 50%; moz-background-clip: initial; moz-background-origin: initial; moz-background-inline-policy: initial" > Look-up
only in the Source symbol table.< / span > < / i > < / p >
< / td >
< / tr >
< tr bgcolor = "#999999" >
< td width = "25%" >
< p > < font color = "#000000" > < font face = "Courier" > < b > < span style = "BACKGROUND: 0% 50%; moz-background-clip: initial; moz-background-origin: initial; moz-background-inline-policy: initial" > SYM
name = ####< / span > < / b > < / font > < / font > < / p >
< / td >
< td width = "75%" >
< p > < i > < span style = "BACKGROUND: 0% 50%; moz-background-clip: initial; moz-background-origin: initial; moz-background-inline-policy: initial" > Add
(or update) a symbol in the User table with the new Address.< / span > < / i > < / p >
< / td >
< / tr >
< tr bgcolor = "#cccccc" >
< td width = "25%" >
< p > < font color = "#000000" > < font face = "Courier" > < b > < span style = "BACKGROUND: 0% 50%; moz-background-clip: initial; moz-background-origin: initial; moz-background-inline-policy: initial" > SYM
! name< / span > < / b > < / font > < / font > < / p >
< / td >
< td width = "75%" >
< p > < i > < span style = "BACKGROUND: 0% 50%; moz-background-clip: initial; moz-background-origin: initial; moz-background-inline-policy: initial" > Remove
a symbol from the User table.< / span > < / i > < / p >
< / td >
< / tr >
< tr bgcolor = "#999999" >
< td width = "25%" >
< p > < font color = "#000000" > < font face = "Courier" > < b > < span style = "BACKGROUND: 0% 50%; moz-background-clip: initial; moz-background-origin: initial; moz-background-inline-policy: initial" > E
symbol ##< / span > < / b > < / font > < / font > < / p >
< / td >
< td width = "75%" >
< p > < i > Set memory (at the symbol Address) to the 8-Bit (byte) Value.< / i > < / p >
< / td >
< / tr >
< tr bgcolor = "#cccccc" >
< td width = "25%" >
< p > < font color = "#000000" face = "Courier" > < b > EB symbol ####< / b > < / font > < / p >
< / td >
< td width = "75%" >
< p > < i > Alias for E.< / i > < / p >
< / td >
< / tr >
< tr bgcolor = "#999999" >
< td width = "25%" >
< p > < font color = "#000000" > < font face = "Courier" > < b > E8 symbol ####< / b > < / font > < / font > < / p >
< / td >
< td width = "75%" >
< p > < i > Alias for E.< / i > < / p >
< / td >
< / tr >
< tr bgcolor = "#cccccc" >
< td width = "25%" >
< p > < font color = "#000000" > < font face = "Courier" > < b > EW symbol ####< / b > < / font > < / font > < / p >
< / td >
< td width = "75%" >
< p > < i > Set memory (at the symbol Address) to the 16-Bit (word) Value.< / i > < / p >
< / td >
< / tr >
< tr bgcolor = "#999999" >
< td width = "25%" >
< p > < font color = "#000000" > < font face = "Courier" > < b > E16 symbol ####< / b > < / font > < / font > < / p >
< / td >
< td width = "75%" >
< p > < i > Alias for EW.< / i > < / p >
< / td >
< / tr >
< / tbody >
< / table >
< p > < br >
< br >
< / p >
< p > < font size = "4" > < b > Examples< / b > :< / font > < / p >
< table bgcolor = "#000000" border = "0" cellpadding = "2" cellspacing = "0" width = "799" >
< COLGROUP >
< col width = "276" >
< col width = "515" >
< tbody >
< tr bgcolor = "#00b8ff" >
< td bgcolor = "#30c0ff" width = "276" >
< p > < font color = "#000000" > < b > Input< / b > < / font > < / p >
< / td >
< td bgcolor = "#30c0ff" width = "515" >
< p > < font color = "#000000" > < b > Effect< / b > < / font > < / p >
< / td >
< / tr >
< tr bgcolor = "#000000" >
< td width = "276" >
< p > < font color = "#00b8ff" > < font face = "Courier" > < b > SYM< / b > < / font > < / font > < / p >
< / td >
< td width = "515" >
< p > < font color = "#ffffff" > < i > Displays number of symbols in the Main, User, and Source
tables.< / i > < / font > < / p >
< / td >
< / tr >
< tr bgcolor = "#000000" >
< td width = "276" >
< p > < font color = "#00b8ff" > < font face = "Courier" > < b > SYMMAIN CLEAR< / b > < / font > < / font > < / p >
< / td >
< td width = "515" >
< p > < font color = "#ffffff" > < i > Clears the main symbol table!!< / i > < / font > < / p >
< / td >
< / tr >
< tr bgcolor = "#000000" >
< td width = "276" >
< p > < font color = "#00b8ff" > < font face = "Courier" > < b > SYMMAIN LOAD APPLE2E.SYM< / b > < / font > < / font > < / p >
< / td >
< td width = "515" >
< p > < font color = "#ffffff" > < i > Reloads the main symbol table.< / i > < / font > < / p >
< / td >
< / tr >
< tr bgcolor = "#000000" >
< td bgcolor = "#000000" width = "276" >
< p > < font color = "#00b8ff" > < font face = "Courier" > < b > SYM FA62< / b > < / font > < / font > < / p >
< / td >
< td bgcolor = "#000000" width = "515" >
< p > < font color = "#ffffff" > < i > Look up the Address $< b > < font color = "#ffff00" > FA62< / font > < / b > (RESET).< / i > < / font > < / p >
< / td >
< / tr >
< tr bgcolor = "#000000" >
< td bgcolor = "#000000" width = "276" >
< p > < font color = "#00b8ff" > < font face = "Courier" > < b > < span style = "BACKGROUND: rgb(0,0,0) 0% 50%; moz-background-clip: initial; moz-background-origin: initial; moz-background-inline-policy: initial" > SYM
HOME< / span > < / b > < / font > < / font > < / p >
< / td >
< td bgcolor = "#000000" width = "515" >
< p > < font color = "#ffffff" > < i > Look up the Address $< b > < font color = "#ffff00" > FC58< / font > < / b > (HOME).< / i > < / font > < / p >
< / td >
< / tr >
< tr bgcolor = "#000000" >
< td bgcolor = "#000000" width = "276" >
< p > < font color = "#00b8ff" > < font face = "Courier" > < b > < span style = "BACKGROUND: rgb(0,0,0) 0% 50%; moz-background-clip: initial; moz-background-origin: initial; moz-background-inline-policy: initial" > SYM
LIFE = 300< / span > < / b > < / font > < / font > < / p >
< / td >
< td bgcolor = "#000000" width = "515" >
< p > < font color = "#ffffff" > < i > Define a new user symbol, called <20> Life<66> at Address $0300.< / i > < / font > < / p >
< / td >
< / tr >
< tr bgcolor = "#000000" >
< td bgcolor = "#000000" width = "276" >
< p > < font color = "#00b8ff" > < font face = "Courier" > < b > < span style = "BACKGROUND: rgb(0,0,0) 0% 50%; moz-background-clip: initial; moz-background-origin: initial; moz-background-inline-policy: initial" > E
LIFE 64< / span > < / b > < / font > < / font > < / p >
< / td >
< td bgcolor = "#000000" width = "515" >
< p > < font color = "#ffffff" > < i > Set 8-Bit variable (@ $< b > < font color = "#ffff00" > 0300< / font > < / b > )<29> Life<66>
to 100 (decimal).< / i > < / font > < / p >
< / td >
< / tr >
< tr bgcolor = "#000000" >
< 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%; moz-background-clip: initial; moz-background-origin: initial; moz-background-inline-policy: initial" > ew
life 3e8< / span > < / b > < / font > < / font > < / p >
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< / td >
< td bgcolor = "#000000" width = "515" >
< p > < font color = "#ffffff" > < i > Set 16-Bit variable (@ $< b > < font color = "#ffff00" > 0300< / font > < / b > )<29> Life<66>
to 1000 (decimal).< / i > < / font > < / p >
< / td >
< / tr >
< / tbody >
< / table >
< p >
< br >
< / p >
< / body >
< / html >
