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

Tony Duell ard at p850ug1.demon.co.uk
Fri Dec 10 13:01:05 CST 2010


> 
> > It would be very useful to know if this is a floppy controller error or a
> > hard idsk cotnroller error.
> 
> Yes, I'd like to know that myself!

I'cve had a look at the I/O board schematics on thw web, the Widget 
interface seems to be a parallel  8bit data bus + control lines, somewhat 
akin to SASI/SCSI. It's implemented using a 6522 adn a little TTL. 

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.

> > Right. This is a Sony 400K drive, as in the other Lisa, right? To
> > eliminate the silly faults, I would at least check the power at the drive
> > connector, and also see what the various signals are doing.
> 
> Good idea.

>From the I.O board schematics, it appears the floppy controller and 
interface is what I'd expect...

> > 2) Check the logic signals the floppy drive interface connector. Is there
> > any activity (changing signals) here? Anything chenge when you put a disk 
> > in?
> 
> Nope the drive is dead.  And this time even with DD disks!  Lights are on 
> inside it though so it might be getting power.  The drive's been 
> cleaned/relubed and the platter turns.  It would be worth me checking out 
> the signals on the card edge though and comparing them to the working 
> machine.

That's what I meant. Do any of the signals on the interface conenctor 
change when you put a DD disk in?

> 
> > 4) The floppy coitnroller has its own 6504 microprocessor I believe. Can
> > you see activity (changing signals) on the address and data bus of this
> > processor?
> 
> 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. 

-tony



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