elg@killer.UUCP (Eric Green) (01/11/88)
Is there any reason why the 6522's shift register can't be used for fast mode?
I just looked at the 6522 data sheet, and its shift register isn't
significantly different from the 6526's... so why is there a 6526 in the
1571? Is there some bug in the 6522?
This was all prompted by a piece of mail I got, asking if it would be possible
to use a 1541 in fast mode with a C-128. The 1541, of course, doesn't have a
6526 in it, and, of course, the 6526 isn't pin-compatible with a 6522...
which means that if it's possible, with few modifications, it better darn well
be possible with a 6522 (sorry, I refuse to consider daughter-boards,
impossible to wire-wrap'em and hacking up your 1541 is hardly something to be
done on a mass-produced basis, 1541 Flash! to the contrary).
--
Eric Lee Green elg@usl.CSNET Asimov Cocktail,n., A verbal bomb
{cbosgd,ihnp4}!killer!elg detonated by the mention of any
Snail Mail P.O. Box 92191 subject, resulting in an explosion
Lafayette, LA 70509 of at least 5,000 words.daveh@cbmvax.UUCP (Dave Haynie) (01/13/88)
in article <2770@killer.UUCP>, elg@killer.UUCP (Eric Green) says: > Is there any reason why the 6522's shift register can't be used for fast mode? > I just looked at the 6522 data sheet, and its shift register isn't > significantly different from the 6526's... so why is there a 6526 in the > 1571? Is there some bug in the 6522? Yup. The 6522 shift register doesn't work right, I think it sees extra clocks on occasion, or something like that. When designing the 1571, Greg Berlin looked at 6522s and even CMOS 65C22s made by GTE and Rockwell, but to no avail; you need a 6526. So you're not going to get a 1541's 6522 talking Fast Serial reliably. The C64, of course, does have 6526s in it. > Eric Lee Green elg@usl.CSNET Asimov Cocktail,n., A verbal bomb -- Dave Haynie "The B2000 Guy" Commodore-Amiga "The Crew That Never Rests" {ihnp4|uunet|rutgers}!cbmvax!daveh PLINK: D-DAVE H BIX: hazy "I can't relax, 'cause I'm a Boinger!"