Adrian,
I used to sell the old PET 2001 from CBM complete with 'chiclet' keyboard.
Adrian Vickers wrote:
> 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
>
> or
>
> 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:
> 10
> 2
> READY.
>
> 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.
>
> FORI=0TO10:?I;:NEXT
>
> 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?
>
I would try the RAM first. Swap all the 8K RAM chips about. That used to do
wonders. It should be your first line of defense.
>
> 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.
>
Swap the memory chips and keep track of what goes where. If a certain chip is
flakey it will show up.
> 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....
>
Proprietary ROMs have been upgraded using modern chips. See Mike Holley's
Southwest Technical Products site offering a ROM monitor upgrade:
http://home.attbi.com/~swtpc6800/ROM_Emulator/ROM_Index.htm
Eric
>
> Thanks in advance!
> --
> Cheers, Ade.
> Be where it's at, B-Racing!
> http://b-racing.com
Received on Fri Jan 17 2003 - 20:25:01 GMT