Okay, remember that probably-a-320 I've mentioned a few times this past
week, the one I was doing HP-IB hackery for?

:-(

I got some external HP-IB interface circuitry built.  It took some
experimentation, because the documentation I have does not completely
describe all relevant aspects - for example, I find it does not work to
hold NDAC active during the idle time between data bytes.

When I finally got it working, I found a stuck-at-0 fault on one of the
data pins.  This is particularly discouraging because now, when I
connect everything up without my circuitry (a setup that worked
before), it doesn't work, raising the depressing likelihood that I
managed to fry something.  (The most plausible theory I have is that I
managed somehow to short the relevant data pin to one of the power
supply rails and blew an output driver.)

This is probably not unfixable, especially if someone can tell me what
an 1820-2058 is in enough detail for me to lift the pin driving that
data line and tack on a discrete-component functional equivalent.  But
given one such accident, I'm rather hesitant to try again, for fear of
frying something else.

So I'm coming at things from another tack.  The machine I was working
on (which *is* a 320, at least if the bootblock report back when I
could boot from disk is to be believed) does not have anything I
clearly recognize as ROM.  There are four large sockets in one corner,
two of which are empty and the other two of which contain an 1818-3771
and an 1818-3772.  Neither one bears a number I recognize as any kind
of ROM, though the -3772 is a CN83790N, which google finds lots of
people selling (but no info on what it is).

However, I have some other machines, which I hadn't been using because
they've got only 4M of RAM (the 320 has 6M).  Since I now appear to
have no working HP-IB disk (possibly excepting the half-gig drive that
weighs about what I do and is not very accessible), I can't see what
the bootblocks report for it.  But its CPU board does have a 68851,
leading me to think it's a 319 or 330, and *its* ROMs are 27256s.

So I pulled them and dumped them, and they basically make sense when
looked at as 68k code, though I haven't gone through it in full detail.

My questions now--

1) Can I take this CPU board - the one with the 68851 - and put it in
    the 320 chassis in place of the 320 CPU board?  It's mechanically
    compatible in most respects, but it does have a second connector
    that the 320 CPU board and chassis do not have - will it degrade
    gracefully and compatibly if that goes unconnected?

1a) If not, how difficult would it be to wire up the 320's expansion
    slots to the 330/319 enclosure's backplane?  (For example, are the
    buses electrically compatible - wire count, signal levels, etc?)

2) Does anyone have ROM images they can send me for this CPU that know
    how to netboot?

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