Re: VIA shift register

From: Francesco Messineo <francesco.messineo_at_gmail.com>
Date: Thu, 10 Jan 2019 17:29:56 +0100
Message-ID: <CAESs-_w+wRqg84qCmAtqQ4qRN9aXzys+AFOR=eeNe+KLKM8YLg@mail.gmail.com>
On Thu, Jan 10, 2019 at 4:42 PM smf <smf@null.net> wrote:
>
> On 10/01/2019 15:32, Francesco Messineo wrote:
> > But both the 1571 and C128 use 6526's serial shifter, so they aren't
> > affected by 6522's bug.
>
> I know, I was just pointing out that the external hardware for direction
> control wasn't just required by the 6522 hardware fix.
>
> I don't remember why the 1571 needed it.

looking at the schematics, it's to "open-collector" the output.
Not sure why the C128 doesn't need it :) (Probably because it's
supposed to be the only device in the bus not having an open collector
output on these two lines in burst mode)? Anyone?

Frank
Received on 2019-01-10 18:00:02

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