Author Topic: Sys 80 Non CPU boot/IRQ issue  (Read 3610 times)

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Marty Machine

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Re: Sys 80 Non CPU boot/IRQ issue
« Reply #75 on: May 30, 2009, 09:24:47 PM »
U2/U3 proms don't need clocks.

I'd monitor cpu pin40 (reset) which will toggle during bootup. (proves cpu is booting).
if pin40 is stuck, this is also feeding the 3 PIA's they might all be held in reset mode....

Z7,8,9,10 are all to do with prom/address decoding for various size proms....shouldn't be a problem, as your problem seems to be earlier than all that....