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| subject: | Re: Seeking reverse-engineers - Apple II VisiCalc |
Hi All, I played with the version on asimov whose reference has given by Eric and here is my conclusion: what do you really want to get? The boot process is the following: 1- VC/80 1 is loaded at $0804..$08FF and then executed. 2- that code then loads the hidden part of VC/80 1 from $0900..$34FF 3- jump to $1800 4- do you want a 80-column display? 4a- if yes, do you have a videx? 5- move $1600..$16FF to $0000..$00FF 6- move $1700..$17FF to $0300..$03FF Then, second step: 1- BRUN VC/80 2 from $0804..$08FF 2- that code then loads the hidden part of VC/80 2 from $3200..$9FFF 3- jump to $18B7 4- copy 8 bytes table from $1A00..$1A3F to the screen holes in $0400..$07FF 5- jump to $0936 for a 80-col display or $09F1 for a 40-col display Third step: 1- copy $0A0E..$0B0D to $0060..$015F 2- jump to $0060 2a- copy $3200..$33FF to $0200..$03FF (but keep $03E0..$03FF values) 2b- copy $3800..$9FFF to $0800..$6FFF 2c- jump to ($0028) The code at $0060 sets the final jump address depending on the display mode and the videx card: the standard 40-col display mode sets those to $37 and $5A therefore the entry point is $5A37. Gotcha ;-) If you want the create the source code of the program then make it from the following RAM addresses: - $0000..$00FF - $0200..$03FF - $0800..$6FFF If you are patient, create the source code of the included DOS: - $A000..$BFFF Good luck, Antoine Vignau Brutal Deluxe Software --- SBBSecho 2.12-Win32* Origin: Derby City Gateway (1:2320/0) SEEN-BY: 10/1 3 34/999 120/228 123/500 128/2 140/1 222/2 226/0 236/150 249/303 SEEN-BY: 250/306 261/20 38 100 1404 1406 1410 1418 266/1413 280/1027 320/119 SEEN-BY: 393/11 396/45 633/260 267 712/848 800/432 801/161 189 2222/700 SEEN-BY: 2320/100 105 200 2905/0 @PATH: 2320/0 100 261/38 633/260 267 |
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