Re: ...thoughts on Retro-uC?

On Thu, Sep 13, 2018 at 8:50 AM <groepaz@gmx.net> wrote:
>
> Am Donnerstag, 13. September 2018, 07:53:46 CEST schrieb Francesco Messineo:
> > On Thu, Sep 13, 2018 at 7:43 AM Baltissen, GJPAA (Ruud)
> >
> > <ruud.baltissen@apg.nl> wrote:
> > > > if a 6526 clone would be simple - we'd have one by now
> > >
> > > I see it in a different way: if there was a demand for the 6526, we would
> > > have one by now.
> > >
> > > Take the PLA as example: there was demand for it and one or more guys cam
> > > with the EPROM solution and others various CPLD replacements. So IMHO as
> > > soon there is a real demand for it, somebody will create a replacement.
> > Well, I agree more with Ruud, but the example is not well chosen
> > because the PLA is easy (if we exclude timings problems, but if you
> > use an EPROM, you're anyway adding different timings), CPLD versions
> > of the PLA can be exact replacements even timing-wise.
> > 6526 isn't so eadiesy, it's a complex piece of statefull logic, but it's
> > doable. There're probably still too many real parts to start worrying.
>
> i've seen far more dead CIAs than dead PLAs so... oh well :)

sure, same here, it's like 10 dead (or almost, actually) CIAs against
1 dead PLA, and the ratio in the good old '80s was even larger.
The reason is the CIAs are sitting naked against the external world:
joystick ports, user port, IEC bus (well, the IEC bus has some gates
between the wild world and the CIA ports anyway).
We used to experiment (most of us), connect the wrong thing on the
user port, plug and unplug things with everything powered on...
I have tens of CIAs with just one or two bits on a port broken and
otherwise working well.
PLAs on the other hand could only die because poor manufacturing
process (the CBM ones) coupled to high power dissipation, but I still
have to find a broken original programmed PLS100 or 82S100.

Frank