apple Lisa2. One working!! - one to go?

[terry stewart]

> The data lines are used for some other function (contrast control I
> think), so if that works the 6522 is probably working. If there's a hard
> disk problem it's in the Widget itself.

Now that's interesting.  The knob which I assume is the contrast (just below 
the brighness one) appears to do absolutelyt nothing?

> That's what I meant. Do any of the signals on the interface conenctor
> change when you put a DD disk in?
>> I swapped out with a known good one, and it didn't make any difference.
>
> Err no. The point of checki nthe signals is not because I suspect the
> 6504 iteslf, but because I wanty to know if it's doing anything. A
> microprocesosr cna appear 'dard' becuase it's not getting a clock signal,
> or because it's being held in the reset state.

Right.

No chance to look at the Lisa last night but the weekend should give me some 
time out in the computer shack.  I'll check the 6504 signals and also those 
on the floppy card edge.  If I find anything unsual on the latter I'll try 
and follow it back through the circuit.

Thanks for the analysis and suggestions.

Terry