Re: Hardware emulation of 6509 using 6502?

From: Dr Jefyll <laughton_at_cyg.net>
Date: Sun, 25 Feb 2018 15:09:32 -0700 (MST)
Message-ID: <1519596572895-0.post@n4.nabble.com>
Jim Brain wrote
> I don't think so.  6509 requires external clocks, but the 652 uses an 
> internal clock generator.

I'd forgotten that -- sorry.  What you did was worth a try.  Tidy, too.

Again I'll suggest an UN-tidy solution, a temporary one at least.  Using a
flying lead, is there a point on the motherboard that's a slightly earlier
version of what gets applied to the Phi2 input (pin 40) of the 6509?  If so,
it could drive the 6502's Phi2 input (pin 37).


Francesco Messineo wrote
> on your setup the data bus on a write is asserted too late (in facts,
> the data written is the "old" data bus value).

Hmm, I'd be careful about such a conclusion.  With samples taken on the
RISING edge of Phi2, the data could easily be misleading.






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Received on 2018-02-26 00:00:35

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