Re: Help! Need older version of Allison (Vision Plus card)

[aiiadict@gmail.com]

Mitchell Spector wrote:
> Or if someone out there
> knows how to patch the firmware check, that'd work too. :)
>

firmware check has to look at CX00 for ROM "signature"....

disassemble (or use sector editor), search for:

** C*

It will also be doing an LDA, so you can search for:

LDA ** C*

there must be some code that cycles through C700 to
C100 in (hex)100 bytes per step:

LDX 1
LDA #C1          (hibyte)
sta check+2
lda #00             (lobyte)
sta check+1

check lda $C100   (load from C100 to C700)
cmp (whatever)
BNE next
BRK

inx
cpx #8
beq nocard

INC check+2

jmp check..

nocard  "no card found"


I think it should be looking for more than one byte
to identify the ROM?

Rich