Path: utzoo!mnetor!uunet!husc6!uwvax!rutgers!cbmvax!daveh
From: daveh@cbmvax.UUCP (Dave Haynie)
Newsgroups: comp.sys.cbm
Subject: Re: 6522/fast mode
Message-ID: <3138@cbmvax.UUCP>
Date: 12 Jan 88 17:42:52 GMT
References: <2770@killer.UUCP>
Organization: Commodore Technology, West Chester, PA
Lines: 20

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!"