John Kortink wrote:
> On Sun, 11 Dec 2011 17:12:00 -0600, Jules Richardson
> <> wrote:
>
>> John Kortink wrote:
>>> I've just acquired a 32016 Second Processor, and I've
>>> noticed that this one has a 32082 MMU on board.
>> Hmm, a very rare beast indeed. My memory's telling me that the socket (or
>> solder pads) next to the CPU were intended for a 32081 FPU, not an MMU (and
>> indeed a have a disk claiming to be for FPU soak tests).
>
> As far as I have been able to determine, an FPU is
> standard. And it's not the one next to the CPU. The
> FPU has 24 pins, and is 'southwest' of the CPU.
Argh, yes, you're right. I had it in my head that Acorn quoted the FPU as
being an optional part, and so assumed that its logical spot was IC2 - but
it does seem that it's IC20 on the 'small' copro, and as far as I can
remember, every single one of those that I've seen has had a chip fitted in
that location.
>> I just had a quick
>> trawl of what scanned docs I have here and unfortunately can't see anything
>> that says one way or the other, but I'll try and take a better look when I
>> get a chance.
>>
>> Is this a 256K/1MB board (the "small" 32016) or a 1MB/4MB board (the
>> "large" 32016)?
>
> Small. It's the actual cheese wedge.
Aha, I have seen them fitted to a couple of ACWs too, although the vast
majority of them got the 'large' board (and every single ACW I've seen has
been different in some way; there's no concept of a standard machine!).
Purely for curiosity's sake, what speed is the CPU on your board? I've seen
both 6MHz parts and 8MHz parts fitted in the cheese wedge cases. The
'large' boards in the ACW seem to mostly have been 10MHz (and I can't
recall off the top of my head what the 1MB ACW that I kept has -
unfortunately I can't quite read the top of the chip on my photos)
>> (I've only ever seen solder pads on the small boards,
>> whereas the large boards typically have sockets fitted - but not populated
>> with a chip; that's from a sample of maybe 20 small boards and 10 large ones)
>
> The socket on this one is definitely (visibly) an
> upgrade. So it stands to reason that the 32082 was,
> too. I'm not convinced the MMU does anything right
> now. At least it stays a lot cooler than the other
> chips.
Yes, I've never seen a socket fitted in IC2's spot on the small boards,
just solder pads.
> There's also a link just east of it that says 'LK4
> MMU'. I suppose that may be an enable, but it's not
> set, which would support the theory that the MMU is
> not actually enabled.
No, that's right I think... I've got photos here of five different small
boards and they all have no socket, no MMU, and LK4 is set - which suggests
that it needs to be removed to enable it.
Given that the copro runs fine without an MMU, I expect it needs extra
software or firmware to make an MMU-equipped one "do something", i.e
there's no code in standard Pandora or PANOS to support it. Are you able to
image the ROMs? All the small boards that I've been able to check ROMs on
have exactly the same copy of Pandora, so it might be worth checking just
to see if yours has something unusual.
I take it there's nothing potentially-useful that "came with" the copro?
Floppies, hard disk, tape etc. that might contain something relevant?
cheers
Jules
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