Re: Strange 8255 behavior

From: Francesco Messineo <francesco.messineo_at_gmail.com>
Date: Thu, 14 Jun 2018 14:55:22 +0200
Message-ID: <CAESs-_xgYsz0H=pUCZukkLazJAnOcmwJaxyG=ZkMa3uTNph16A@mail.gmail.com>
On Thu, Jun 14, 2018 at 2:48 PM, Michał Pleban <lists@michau.name> wrote:
> Francesco Messineo wrote:
>
>> the 1508 has 128 macrocells, the EPM7256E has 256 macrocells.
>> An ATF1502 can fit a 24 I/O pins with separate DDR control on each
>> pin, it's in the
>> examples of wincupl.
>
> That's for sure, but 6526 is much too more than a few I/O chips. You
> have two 16-bit counters, interrupt logic, TOD clock, serial port etc.
> All this uses macrocells - basically you need to counf one macrocell for
> every bit that is being latched in aby way, plus extra macrocells for
> some decoding logic etc. I counted all the latches in the 6526 once and
> the result was more that 128.

yes I know how to count macrocells, I just didn't check how many would
be needed for a 6526.
128 is quite a lot I would think.


>
> I wasn't aware of the 256-cell CPLD though, I work with the Ateml ones.
> That one might be big anough, but can you still purchase it in bigger
> quantities? The Atmel chips are still being made, wheread the Altera one
> have been discontinued long ago.

yes EPM7xxx can still be found, but Intel made them very expensive
after they bought Altera, basicly they're not a real option anymore
:(

F
Received on 2018-06-14 15:02:13

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