[Techtoolslist] Slowing down a Fluke Z80 pod?

David Gersic info at zaccaria-pinball.com
Sun Sep 17 12:38:49 EDT 2017


This is going to seem like a strange thing to want, but is it possible to slow 
down a Z80 pod?

I have a 9010 and the Z80 pod for it. As far as I know, both are working fine. 
I don't have anything with a Z80 in it to test to prove that.

What I picked these up for is to use with a Signetics 2650 adapter 
(http://www.arcades.plus.com/s2650_fluke_adapter.htm) on Zaccaria boards. It 
seems like this should work, but in practice it's very unreliable.

Test reading data from ROM on a known working board, sometimes I get correct 
data, most of the time I get random garbage. If I read a byte from the same 
address 10 times, maybe one time will be correct.

Test RAM, it'll go a few bytes in to the test, then "fail". If I loop on that, 
it'll eventually pass, then fail a byte or two later. This seems to be 
essentially the same symptom as displayed by the ROM reading test.

The adapter board is based on the old Fluke "Troubleshooter" article from 
1983. As far as I can see, the board is doing what it's supposed to do, moving 
signals from the Z80 to where the 2650 expects them to be.

So what I'm thinking is that the Z80, running at a faster clock speed than the 
2650, is just over-running what a board designed for a slower processor can 
deliver. Is it possible to slow down the clock speed on the Z80 pod?



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