Re: Did Commodore cheat with the quad density floppies?

From: Francesco Messineo <*francesco.messineo_at_gmail.com*> Date: Thu, 10 Jan 2019 20:11:44 +0100 Message-ID: <CAESs-_yGkQTpVEBovq9LQ3yGv9ur+aEOANXrNU+yxnZ=ccFC_A@mail.gmail.com> · francesco.messineo_at_gmail.com

On Thu, Jan 10, 2019 at 7:54 PM Jim Brain <brain@jbrain.com> wrote:
>
> On 1/10/2019 12:40 PM, Mia Magnusson wrote:
>
> Den Wed, 9 Jan 2019 12:52:46 +0100 skrev Francesco Messineo
> <francesco.messineo@gmail.com>:
>
> see how they did the "burst mode" between 1571 and C128. On the 1571
> there's an additional 6526 with only two pins used, they didn't even
> bother to substitute one of the 6522.
>
> That was surely done to make the 1570/1571 as compatible to a 1541 as
> possible, to make for example copy protection work better.
>
>
>
> As I recall, tho, they used all of the previously free 6522 IO pins, as the parallel cable on a 1571 has to be put on the 6526...

they used 6 of the 8 previously free PA pins.

Frank