Xerox 820-II troubleshooting - need advice

[Tony Duell]

> 
> On 26 Apr 2009 at 17:50, Tony Duell wrote:
> 
> > But certainly possible with real computers like PDP8s, PDP11s, PERQs,
> > HP9000/200s, machines with HPIB or HPIL ports (+ the right interface
> > converter), Commodores (most had user ports IIRC), BBC micros, etc,
> > etc, etc
> 
> It was meant as a jab to an earlier pro-Mac post about how PC's 
> aren't "real" computers.

Sure. I was just pointing out there are plenty of real computers which do 
have parallel/user ports. 

> 
> > Alternatively, can't you see if the existing keyboard is sending
> > anything using a logic probe?
> 
> Both approaches are valid, but I suggested the parallel port because 
> (1) it's easy to do and (2) if it's the keyboard that's gone south, 

If you have a logic probe to hand (OK, I do, maybe most people don't), I 
suspect it's a lot quicker to put it on the keyboard strobe pin and then 
on the data pins while pressing keys to see if anything is coming out of 
the keyboard rather than to make a cable to link the keyboard port to a 
PC parallel port and then write the (trivial) program needed to simulate 
the keyoard.

> one can use the parallel port option to check out the rest of the 
> machine until the keyboard fault was islolated and repaired.

True.

-tony