Apple Disk II, was Re: TRS-80 Model I

[Pete Turnbull]

Dave McGuire wrote:
> On Feb 4, 2007, at 4:05 PM, Tom Peters wrote:
>> Before even letting the customer leave the premises, I'd quickly take 
>> out the four screws that held on the cover and show them the blackened 
>> spot on the inside of the cover, then show them the 74LS125 in the 
>> middle of the board, which invariably had been cracked or cratered.

I remember it well :-)

>> The documentation clearly said, connect the ribbon cable to the 
>> controller with the cable exiting AWAY from the board. But there were 
>> any number of folks that went the long way around, and put a great 
>> deal of effort into bending the cable sharply where it exited the ID 
>> connection, so that they could plug it into the controller card 
>> backwards.

Or the right way round, but one pin displaced, sometimes.

>> This usually resulted in a spectacular failure of the '125.
> 
>   Did that failure take out anything else, or did replacing only the 
> 74LS125 solve the problem?

9 times out of 10, that was the only replacement required.  If you were 
unlucky, you might also lose the MC3470, but I only ever had to replace 
about half a dozen of those.

-- 
Pete						Peter Turnbull
						Network Manager
						University of York