9 Sep
2005
9 Sep
'05
7:25 p.m.
On 9/9/05, Cini, Richard <Richard.Cini at wachovia.com> wrote:
If you can find it, get a ROM dump or listing from one
of the floppy drives
like the 2031LP disk drive or the 2040 dual-drive. The 2031 is a
1541-looking GPIB floppy drive for the PET.
http://www.funet.fi/pub/cbm/firmware/drives/old/2031/index.html
If you want to look at the circuit the 2031 uses...
http://www.funet.fi/pub/cbm/schematics/drives/old/2031/page-28.gif
(it's a 6522 VIA with 75160/75161 GPIB interface chips, much like a
similar design I saw on a 3rd party VIC-20 GPIB interface)
It's not what the original questor was after, but it might be helpful
in trying to mark up a state machine based on how Commodore
implemented GPIB (or to implement your own on another flavor of
machine).
-ethan
