Re: identifying an unknown eprom content

From: Francesco Messineo <francesco.messineo_at_gmail.com>
Date: Thu, 27 Aug 2020 12:56:25 +0200
Message-ID: <CAESs-_xx+tnaPKXp4y9b22iviEbOrgbNEQJQex8isPTc1+gLww_at_mail.gmail.com>
Hi,
just a suggestion: when you reverse engineer some unknown firmware,
you NEED also to have a complete schematic of the system before you
start.
So if you don't have a schematic, you need to first reverse engineer a
good schematic.
I tell you that from my own experience on reverse engineering these
kind of old and undocumented boards.
The code starts to make sense (and you can start making sense of it)
once you know where RAM/ROM and whatever else (I/O) is mapped.

HTH
Frank IZ8DWF

On Thu, Aug 27, 2020 at 12:49 PM <didier_at_aida.org> wrote:
>
> 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
>
>
Received on 2020-08-27 13:01:57

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