Re: did anyone actually try this MPS6550?

From: Francesco Messineo <francesco.messineo_at_gmail.com>
Date: Mon, 31 Dec 2018 09:13:01 +0100
Message-ID: <CAESs-_xDaGiZz8DsEdZnHM-xHNmrEF7U2o91B_McxWD7KDjC=Q@mail.gmail.com>
On Mon, Dec 31, 2018 at 1:09 AM Jim Brain <brain@jbrain.com> wrote:
>
> Is the goal to get a period-correct IC?  Or, is it just to replicate the
> 6550 functionality?

I designed adapters to use 2114 in place of the 6550, so my only goal
would be having the real ones.
The 2001 is currently running with my RAM/ROM replacement board as two
6540 are also missing and the replacements have been lost by italian
post service it seems.

>
> BTW, if there a handy datasheet for the 6550?  Was it available mask
> selectable for various combinations of select lines?

I've never seen a datasheet of the 6550. I believe the various CS pins
have fixed polarity. Also, I've never seen any hint on the part number
printed on the case that there might be a different option.
I have made a test setup that tells me how a 6550 is working or not,
including when it stops obeying to one or more CS lines, so for
example I can use that chip in the video RAM socket of a 2001, where
it's always selected on high part of phi-2. I have such a 6550 on my
2001 video RAM and it's working fine.

Frank
Received on 2018-12-31 10:00:07

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