HP 9836U processor mystery...

Eric Smith spacewar at gmail.com
Tue Nov 7 00:39:47 CST 2017

On Mon, Nov 6, 2017 at 9:59 PM, Tony Duell via cctalk <cctalk at classiccmp.org
> wrote:

> Mine identifies the CPU as a 68010 in the power-on diagnostic. But from
> what
> I remember the PGA socket could also take a 68012 (with extra address pins
> brought out). I don't have such a chip, so no idea what it would identify
> as.

Do you mean that it will actually use the extra address pins?

I suppose the most likely way for the software to identify the MC68012 (vs
MC68010) would be to try accessing two memory addresses differing only in
address bits A24 or higher (but not A30), and test whether whatever MMU
hardware they've built will actually map them distinctly.  The other
difference in the MC68012 is the availability of a /RMC pin to better
identify read-modify-write cycles, but since their board has to work with
an MC68010, I doubt that it would use the /RMC signal at all.

I've heard claims that HP used the MC68012 in some systems, but I've never
seen any definite confirmation.

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