Re: identifying an unknown eprom content

Am Donnerstag, 27. August 2020, 12:48:58 CEST schrieb didier_at_aida.org:
> I'm trying to identify an eprom with an unknown content
> I was thinking it was the eprom booting the server (a commodore mother
> board without screen nor keyboard in an industrial box)
> (on the commodore we had a network composed of a server and up to 16
> stations)
> I have 2 eproms labeled:   pc-central-26-4.bin (8k)  and
> boot-poste-3.bin  (4)
> the boot-post-3.bin contains the good content...  [the copyright is
> present]
> what I know on the pc-central-26-4.bin:
> - it's a 8k eprom, starts at $E000, the code starts at $E002 before
> there are 2 bytes  $00 $BF
> - it's 6502 code  (seems written by an amateur)
> - there is some code between $E800 and $E8FF so it's not a 8032
> - they are writing something around $8000  and also around $0400
>
> I was thinking that perhaps it was something for a vic20 or a c64 but
> I've not really used this 2 machines
> any idea of what I can do to identify the machine ?
>
> I'm thinking to try to check the use of I/O area but I need a better
> disassembly

start with posting the binaries perhaps? there are a bunch of people here that
could help with some educated guessing :)

one thing to always consider is swapped data and/or address lines - which is
why it helps a lot to have schematics. if you don't, i'd first start looking
for strings, and make sure they all make sense.

typical c64 or vic20 "kernal" rom should have the hardware vectors in the last
6 bytes. typical cartridges have the "cbm80" (or cbmA0 or whatever) signature
in their first few bytes.

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