> > I confirmed what I was seeing with the analyser by having the
>> 452 echo any slave ACKs it saw to one its pins
> 
> Yes, but what were you seeing on the analyser?  From what you are
>  saying, the first thing that goes wrong is an ACK is missed.  Do you
> see this ACK on the bus?  It would be important to know whether
> the slave is failing to ACK, or the master is failing to see the ACK

What I saw on the analyser (and I am so grateful to have one) was
at times an illogical mess of ACKs, NACKs and markers. To the
point where I was disbelieving the analyser. The 452 unfailingly sees
whatever the slave does, whether it be ACK or NACK. I'd look
at the state of the 452's ACKDT bit and set a 452 pin accordingly.
ACKDT bits were also stored in a couple of variables which were
then displayed in binary on an LCD as another visual verification

The whole thing is going to get picked over today and I'll put the
results up on a page. I'd like to know whether this is something
peculiar to the F88 and, if so, under what conditions. I don't, at
this stage, believe there's a problem on the 452 master side

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