Re: Strange 8255 behavior

From: Ruud_at_Baltissen.org
Date: Sun, 17 Jun 2018 09:38:54 +0200
Message-ID: <5B26100E.14149.17BEAE35@Ruud.Baltissen.org>
Hallo allemaal,


I read all those emails regarding the "6525/6526 in a CPLD" problem. 
But I think you forgot one thing: not all functionality of both ICs 
are needed. IIRC Michał mentioned in one of our private emails that 
the timers aren't needed at all. I made a PCB using the ATF1504 but 
IIRC it can be replaced with an ATF1508. Michał knows all the ins 
and outs of what is needed to emulate the internal connections.

A remark of someone NOT familiar with CPLDs and FPGAs:
It is possible one needs a certain number of cells for an input or 
output of either the emulated 6525 or 6526. But if an output and 
input are connected to each other, is that still the case? I can 
imagine that a cell used for an emulated output can be used for the 
emulated input as well.

But AFAIK Michał solved the 8255 problem so the whole discussion is 
not needed anymore.


--
   
Kind regards / Met vriendelijke groet, Ruud Baltissen
www.Baltissen.org
Received on 2018-06-17 10:01:18

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