Re: Hardware emulation of 6509 using 6502?

From: Mia Magnusson <mia_at_plea.se>
Date: Fri, 2 Mar 2018 07:56:20 +0100
Message-ID: <20180302075620.000066f5@plea.se>
Den Fri, 2 Mar 2018 00:48:28 -0600 skrev Jim Brain <brain@jbrain.com>:
> On 3/2/2018 12:08 AM, Jim Brain wrote:
> >
> > All tests passed except eh last one (read back).  It failed.  What 
> > does that mean?
> >
> Duh, read the ASM, got it.
> 
> Is there a way to create more debug info on this test, so I can see
> what you expected, and what you received?
> 
> I *assume* it's because the RAM and the CPLD are fighting for the bus 
> (to be solved with a board rev), but it would be nice to know.
 
But still, does this really need a new board rev? You already detect
those cycles and you already control the P outputs, so as I said
earlier just force P to $F or $E while reading/writing 0/1.

$E would give the technically most correct result on a machine with less
than 960k RAM, while $F would in practice work in all possible cases
except for with some unknown hardware add-on that probably doesn't
exist.

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