Marko Mäkelä wrote:
> A comparison between the 325302-01 and the lower part of the 251968-03
> (1541-II firmware) reveals quite a few changes, including the introduction
> of a copyright message. I just had a look at the differences, but could
> not find any obvious place for the checksum.
I always thought that the unused first page of the $C000 ROM contains the
checksum as well. The first byte is $97, the rest is $AA in the first
version. But in the 1541-II, the first byte is still $97, the second is $E0,
then follows the copyright message and a patch routine, and the rest is again
padded with $AA. Maybe the programmers at Commodore didn't know anymore where
the checksum was and just used the second byte to adjust the checksum? Or is
this first byte used for anything else?
Nicolas
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