[Techtoolslist] Slowing down a Fluke Z80 pod?

[Mike Coates]

   It works on a Zaccaria Invaders PCB, as I have used it on a few of
   those before. mind you these are nice and simple, no pages as
   everything fits into the first 2k !!
   > On 19 September 2017 at 06:12 David Gersic
   <info at zaccaria-pinball.com> wrote:
   >
   >
   > On Sunday, September 17, 2017 12:24:07 PM Ian Eure wrote:
   > > That's not really how it works. The CPU in the pod is driven by the
   > > clock on the PCB. If the pod CPU was running at a different clock
   > > speed, nothing would work at all.
   >
   > Hm. So the adapter ports CLOCK straight across, from Z80 pin 6 so
   2650 pin 38.
   > The Z80, being capable of running at faster clock speeds, should be
   perfectly
   > happy to run slower.
   >
   >
   > > Based on the article, it sounds like perhaps the adapter just
   doesn't
   > > match the timings of the original CPU to support anything other
   than
   > > individual reads, or perhaps there's an issue with your adapter.
   I'd
   > > see if anyone else has used a similar setup and see what results
   they got.
   >
   > The old Fluke article seems like they were trying to match the
   timings, or at
   > least get close enough. Maybe they were good enough for whatever it
   was they
   > were testing when the article was written.
   >
   > I don't know anybody else that works on Zaccaria boards, so no,
   haven't got
   > anybody else that can confirm or deny that this works at all.
   >
   >
   > > If you wanted to slow things down in the hopes of improving
   marginal
   > > timings, you'd need to alter the clock on the PCB, either by
   > > substituting a slowre crystal or by replacing the clock that
   controls
   > > the CPU and bus accesses with a slower signal. Either option almost
   > > certainly guarantees that the video hardware won't work, and may
   mask
   > > other problems going on with the board.
   >
   > Right now, I'm testing on boards that I know to be good. I could try
   swapping
   > in a slower crystal to see what happens, good or bad. But if the pod
   runs at
   > UUT clock speed, I'm thinking that wouldn't be likely to make a
   difference.
   >
   >
   > > Are you aware of Paul Swan's 2650 tester? That might be another
   > > option worth looking into.
   > > http://www.paulswan.me/arcade/ArduinoMegaICT.htm
   >
   > Yes, I've seen that too.
   >
   >
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