Checksum question

[Gregory A. Parmer]

On Mon, 22 Jun 1998, Jason Weir wrote:
> > Since the checksum is part of the rom data, it can't be included in
> > checksum. That would make it self modifying. Once you calculated it,
> > would change the checksum. The checksum, vin, and usually the prom ID
> > not in the checksum calc (on some, the ID is part of the checksum
> 
> That would explain why it changed everytime I tried to calculate it..
> thanks for the help

The EPROM burner SW for my programmer allows you to set the
addresses you're calculating the CS for. Ie, I set it to
start calc'ing the CS from 8 (something like that) thru
the end. Look for a similar option in your SW, verify
the CS on a known good bin, then try it on your modified
one.

-greg

PS-Mine is a XELTEK rommasterII and the Sw is avail as a free
download from www.xeltek.com. If ya try it, be warned that it's
a parallel port programmer so running it with a printer attached
instead will freak out your printer.