ZX Spectrum Z80 Keeps Resetting

Rob Jarratt robert.jarratt at ntlworld.com
Mon Jan 1 15:02:10 CST 2018

> -----Original Message-----
> From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Fred
> via cctalk
> Sent: 01 January 2018 20:36
> To: General Discussion: On-Topic and Off-Topic Posts
<cctalk at classiccmp.org>
> Subject: RE: ZX Spectrum Z80 Keeps Resetting
> Is there a random element to the rebooting, or is it a fixed specific
> Consider, . . .
> if some high order bits of the address are non-functional, then when it
goes to
> location xxx000 , it starts over at 000000.
> Not necessarily the most likely cause of the problem.

Unfortunately it is random. To a point. When I did my trace with the logic
analyser I could see it was in a RAM testing loop and would fail part way
through the loop, failing on an address that previously worked.

However, it manages to get past that bit and gets to the point where the
copyright message is displayed. But it always resets at that point. I have
not been able to capture that point in the address trace to see if it is a
consistent address, but maybe that is something I can try with a trace that
triggers on a stop condition. I will try that this evening.



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