23 Aug
2001
23 Aug
'01
8:36 a.m.
see below, plz.
Dick
----- Original Message -----
From: "Adrian Vickers" <avickers(a)solutionengineers.com>
To: <classiccmp(a)classiccmp.org>
Sent: Thursday, August 23, 2001 3:01 AM
Subject: Re: CBM 8032 SK
These are problems we all wrestle with and yet manage to get handled. Practice,
though it really doesn't make "perfect" does make better, and lack of it
will
make you rusty, if you avoid it for a while. Wanting to avoid soldering and, in
general, dis/re-assembling things is wise. It can't always be avoided, however.
I wasn't aware of a BRA instruction on the 6502. The CMOS parts and MOT had
it
on a number of their later models ...
At 01:56 pm 22/08/2001 -0600, Richard Erlacher wrote:
<snip>
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
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.
--
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