[Diy_efi] Motronic checksum

[FR Wilk]

Do you have a EPROM programmer? The software that comes with it will do the
checksum correctly.

You have another problem. Half the code is stored in the 8051. You have to
download that before you can try a disassembler.

In about 88, BOSCH started putting the whole code into the EPROMs and wiring
the 8051 to ignore its internal memory. This will save you from trying to
download an 8051's ROM.

FR Wilk


----- Original Message ----- 
From: <glogovacs at yahoo.co.uk>
To: <diy_efi at diy-efi.org>
Sent: Wednesday, June 09, 2004 3:07 PM
Subject: [Diy_efi] Motronic checksum


> I am trying to figure out how a checksum on older Motronic eproms is
> formed. I am targeting last 2 bytes on 32kb eproms (actualy, it is last
> 24bits, since the highest 4 bit nibble is always 0000). I was lucky enough
> to have access to eproms for the same car that only had a few different
> locations, and of course the checksum.
>
> I tried 8 bit sum, 16 bit sum... xor etc, but no success :(. I can also
> post examples... Any help is welcome.
>
> Also, can you suggest some good 8051 disassembler? I have d51, but it
> produces much garbage - considering I am dummy for i8051. I was trying to
> locate instruction that would access last two bytes of eprom, and I
failed.
> Where in address space is eprom located?
>
> I am talking about boxes 0 261 200 087 (BMW), 0 261 200 185, 0 261 200 190
> (Opel) and similar.
>
> Nick
>
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