PET 2001 oddity

From: Adrian Vickers <>
Date: Fri Jan 17 12:15:01 2003

I dug the 2001 out of the cupboard the other day - it's reorganise time,
try to get *even more* stuff into exactly the same amount of space as less
(but still lots of) stuff occupied. It never works, but it does give me an
excellent excuse to have a play around with some of them.

Unfortunately, the PET seems to have developed an odd fault: It won't take
a BASIC program, and some keywords seem to be knackered...

It reports 7167 bytes free, as per spec. But if I type:

10 REM blah


10 ?"HELLO"

it hangs. If I load a program from tape, it does one of two things:

a) Loads but won't run, typing LIST produces something like this:

b) It loads & hangs immediately after the READY. prompt comes up.

I tried to put together a FOR loop (the idea being I could use it to
display chunks of memory at a time, e.g.


Instead, the machine goes into an infinte loop displaying zero on a new
line each time (it's ignored the I variable, and the semicolon after the
PRINT command.

If I replace NEXT with NEXTI, it fails reporting NEXT without FOR.

So.... I figure the BASIC ROM has become slightly corrupted, OR I've got a
flakey memory chip which reads OK but doesn't write properly. The question
is, how to find out?

1) Can the BASIC ROM be swapped with one from, say, a 3032 or 4016? In
fact, which one IS the BASIC ROM?
2) If it's a dodgy memory chip, what's the best way of isolating it? I have
an oscilloscope, but nada skill in this sort of thing.
3) If, as my money is on, it's the BASIC ROM, can it be replaced with an
EPROM - if so, there's a whole gamut of additional questions to follow....

Thanks in advance!
Cheers, Ade.
Be where it's at, B-Racing!
Received on Fri Jan 17 2003 - 12:15:01 GMT

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