At 01:56 pm 22/08/2001 -0600, Richard Erlacher wrote:
>Hi, Adrian!
Hi Richard! :)
>If you're going to have "old" hardware, you're sooner or later going to
have to
>deal with DIY, since you can't hire out repairs of the sort you'll both
want and
>trust. OTOH, if you put forth a bit of effort, mostly in the form of
study, and
>invest as much as you can comfortably invest in test equipment and supplies,
>you'll most generally be able to handle the repairs you need done. This is
>especially true since you can get lots of help on this forum.
Agreed - I think I've picked up more advice here in the last two days than
either of the more focussed newsgroups, and even the cbm-hackers list
(which is a bit on the quiet side).
>Learning to operate an eprom programmer should be the least of your
worries, not
>because it's unimportant, but because it's easy.
That makes sense. It's just that I've never used one before, so at this
moment in time, I've not got any idea at all...
>A big part of getting the appropriate equipment is learning enough to know
>what's appropriate. Starting out small and simple is probably the best
route.
>Since we've established that you'll have to do no soldering to (1) replace
the
>EPROMs you lack, and (2) insert the CPU, you can probably breathe a sigh of
>relief, in light of your apparent aversion to attempting such things at this
>juncture. Perhaps that's just as well for now.
Well... It's not that I *can't* solder, it's just that I don't seem to be
very good at it for some reason. It may be that I've got a dodgy iron (I do
need to get one with a much smaller tip if I'm going to start desoldering
ICs), but a) The tip simply won't tin properly, b) It seems to take ages to
warm anything up enough to get the solder flowing. For example, I must have
spent 2 hours building a BBC 'B' monitor cable; and by the time the pin on
the DIN plug got hot, it went a dodgy colour and the solder wouldn't flow
onto it. I did eventually manage to get the cable going, but it was a hell
of a struggle. It didn't help that I don't have a vice here, so I needed
four hands at the time...
>If you replace your missing CPU with one that's as old as the original,
you'll
>have little trouble. Back when the PET was built, there was only one type of
>6502. That's the type you probably want. The CMOS versions were the ones
that
>came up with extra instructions, and, coincidentally, without the
undocumented
>ones that existed in the original.
According to the datasheet (from Farnell) I was reading, the original
didn't have a BRA instruction? That seems somewhat unlikely to me, but is
it true?
>
>You might visit www.6502.org to get a bit more info about this.
>
>If you want, I'll mail you an old 1 MHz 6502, but, since it involves going to
>some trouble, please be sure that you've covered the other bases, so to
speak,
>so the effort won't be in vain. In general, it might not be a bad idea to
find
>someone in your area who has a working version of what you've got under
study,
>just to see if you know what it looks like when it's working right.
Moreover, a
>momentary parts swap can be VERY revealing.
Hmmm - I've tried that one way, which revealed the duff CPU (and
fortunately didn't fry the working machine), but I'm very leery of putting
good parts in a fried machine (for much the same reasons Tony gives, and
unashamedly based on his advice).
Thanks anyhow! I'm starting to really look forward to poking around on this
board - maybe there's (no?) hope for me yet...
Cheers!
Ade.
--
B-Racing: B where it's at :-)
http://www.b-racing.co.uk
Received on Thu Aug 23 2001 - 04:01:53 BST