Re: Hardware emulation of 6509 using 6502?

From: Jim Brain <brain_at_jbrain.com>
Date: Tue, 27 Feb 2018 20:29:25 -0600
Message-ID: <c3af4f55-6a42-64b9-3413-d70f63aeea44@jbrain.com>
On 2/27/2018 5:11 AM, Michał Pleban wrote:
> Hello!
>
> Jim Brain wrote:
>
>
> * Something else is driving the data bus and 6509 has stronger drivers
> which can overcome it, but 6502 doesn't (OK, this doesn't seem likely to
> me, but it's a distant possibility).
>
> I would try placing a 74LS245 between the 6502 and the data bus.
Well, unlikely though this is, it seems to be the culprit.  I added the 
'245 inline, and now the probes on the 6502 see the 06 being written and 
the probes on the PCB see the 06 as well.

Sadly, no boot as yet, but it might be timing related at this point.

Jim


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Received on 2018-02-28 03:00:29

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