With respect to the Commodore choice to put HPIB on their computers, as opposed
to a parallel port, there was a fellow here in Denver who cooked up a circuit
that allowed one to attach a then-common EPSON printer to the HPIB, thereby
making the computer into a useful tool. He became rich beyond his wildest
dreams, and started a company called "Progressive Peripherals" which may in fact
still be in operation.
Since there were, at the time Commodore put these devices on the market,
external HPIB-interfaced HDC's, HDD units, FD units, etc, including printers, it
wasn't a TERRIBLE choice, though it wasn't necessarily the path to the cheapest
solution.
Dick
----- Original Message -----
From: "Adrian Vickers" <avickers_at_solutionengineers.com>
To: <classiccmp_at_classiccmp.org>
Sent: Friday, August 24, 2001 2:48 AM
Subject: Re: CBM 8032 SK (& electronics)
> At 10:57 pm 23/08/2001 +0100, you wrote:
> >> >Actually, I think it's a stupid design.
> >>
> >> Erm, I was thinking more of the way it looks on the desk...
> >
> >Something which (as you'll come to discover if you hang around on
> >classiccmp) I don't care much about. It is certainly well down with
> >respect to functionality.
>
> That's fair enough. Personally, I doubt any of the older computers are
> *truly* elegant internally - there was too much learning going on. I'm not
> even sure if it's true of modern computers either.
>
> Of course, you'll prove me wrong now... ;)
>
>
> >> >The 'separate keyboard' seems
> >> >nice until you move it away from the machine, whereupon the keyboard
> >> >cable unplugs itself from the DB25 on the main unit.
> >>
> >> I never found that to be a problem, although I mostly used it with the
> >
> >Well, just about every other plastic-cased PET owner I know thinks that
> >'SK' stands for 'Stupid Kludge' :-)
>
> Heh. Speaking of kludges, I've got a WordCraft dongle (but no WordCraft) if
> anyone has lost theirs.
>
> >
> >> keyboard in it's looks-like-its-attached position; It would probably have
> >> been better with an IDC connector (ala the Osbourne).
> >
> >Or with locking screws on the DB25...
> >
> >>
> >> > The thing is just
> >> >too wide to fit on a shelf in a 19" rack.
> >>
> >> They're supposed to sit on desks, not racks...
> >
> >So? The thing has a GPIB interface, so it's reasonable to assume it's
> >going to be possibly used to control test equipment. Making it just to
> >wide to sit on a shelf in a rack is very annoying. It's just another
> >aspect of the bad design of this case...
>
> Were Commodore really thinking that? I know the HP stuff was suited to
> controlling 'scopes and the like through the 488 bus, but I don't recall
> them having external drives, printers, etc. controlled via it. ICBW...
>
> >
> >
> >> Internally it's a mess. The PSU is in a crazy position; the 240V supply
> >
> >Agreed. It's really a normal 8032 re-cased, and it doesn't really fit the
> >new case...
>
> Agreed.
>
> >The 8296 (same case, totally revised mainboard) is a lot
> >better in this respect I believe.
>
> I've not seen one of those; I did wonder if the expansion board I've got in
> my 8032 (which turns it into an 8096) would fit, but I don't think there's
> enough height in the -SK case.
>
> >> line is too short and stretches dangerously if the unit is opened to
> >> 90degrees, the balance is all wrong, and yes - it's just an 8032 board
> >
> >I seem to remember it's best to take the monitor off first (Rotate it to
> >free the tilt/swivel base, then unplug the 9 pin mate-n-lock connector).
> >Then the case opens without straining too much of the wiring, and without
> >the darn machine falling over all the time.
>
> Yup, one of the cbm-hackers guys kindly provided a set of instructions on
> how to remove the mainboard with minimum disruption; useful as it means I
> can get to the voltage regulators and check them (they're fine).
>
> >
> >> rotated (although there are subtle differences between the -SK board and
> >> the regular board, although that may just be down to different revisions
> >
> >I think it's just different revisions. There's no reason for any
> >electrical changes to the board.
>
> Indeed. The secondary cassette port is in a different place, and the
> monitor signal connector has moved as well.
>
> >
> >> between the machines. The only reason it doesn't need a "special"
> >> PET-->IEEE cable is because it already has one internally... Useful,
> >
> >Sure....
> >
> >> because I've plundered it to test the diskdrives I've now got with the
> >> regular 8032 (and they work nicely!). Shame they didn't bother to put the
> >> plastic keys in, so there's the possibility of putting it on upside down -
> >
> >Yes, but the average user is not expected to ever unplug the edge
> >connectors inside the 8032....
>
> Well, true.... Are GPIB connectors still reasonably available? I ask
> because the ones which came with the machine (& the cable) have sustained
> some connector damage at some point; they work, but I have to be *really*
> careful connecting them up.
>
> >> luckily that didn't happen to me. Oh yes, the monitor signal & power cables
> >> go through a connector which floats in the middle of the machine - it looks
> >> like someone forgot about that until the last second...
> >
> >Indeed. I can't remember if the normal 8032 has that or not.
>
> No, there's just a bunch of signal wires which drop down onto the main
> board, and two AC lines which mosey up on into the monitor cabinet (which,
> awkwardly, are soldered directly to the PSU).
>
> > The 8296
> >certainly does.... It's useful in that you can remove the monitor easily,
> >and the rest of the machine (PSU + logic board) is then a lot easier to
> >work on...
>
> With the old 8032, I find a suitably calibrated pile of books behind the
> machine can be used to rest the back of the monitor, so you can open the
> case to the extent of the hinge. I used a similar trick with the 8032SK...
>
> >
> >> I think simple, but reasonably useful for now at least; I may need fancy
> >> stuff in the future, but I'd prefer a "beginners" instrument for now. I'll
> >
> >I would not class the 465 (or any Tektronix 'scope) as a 'beginner's
> >instrument' :-). Yes, they can be simple to use, but they have enough
> >facilities to keep you going for a long time. You are not going to
> >outgrow it anytime soon.
>
> :) I have used 'scopes in the past, I guess it's just a case of remembering
> how. And maybe (shock, horror) reading the instructions.
>
> >There are things it won't do, but you rarely want to do them anyway (how
> >often do you need an RF spectrum analyser for computer repair, for example
> >:-)). For displaying waveforms it'll do all you (or I) am likely to need.
>
> Indeed...
>
> >Suffice it to say that a valved 'scope can still be a very useful
> >instrument (I'd much rather have a good valved 'scope than a typical
> >hobbyist grade modern 'scope). But it is going to need a bit of looking
> >after. You are going to have to recalibrate it from time to time, and
> >rebalance the amplifiers, and so on. It's not difficult, but it may not
> >be the sort of thing you want to get into.
>
> Perhaps not *just* yet; I'm sure that the desire will come with time...
>
> >> Agreed. If I don't get the basics learned first, I'd just end up a spare
> >> wheel...
> >
> >Yes. While I'm sure I could fix this PET (and I could even explain what
> >I'd done), you'll learn a lot more by doing it yourself.
>
> Exactly. Watching an expert at work is very educational, but nothing like
> rolling the sleeves up and getting in there oneself. And, with the combined
> skill of this maillist, if I *do* get stuck, I know where to turn for
> assistance.
>
> >
> >> I'll check that. I had to remove the whole gubbins from my working 8032
> >> when the mains filter exploded, but I didn't check any resistances/voltages
> >> there. All the connections have been un-made then re-made, so if the HR
> >> usually comes from mucky connectors, that's unlikely. If the cap is going,
> >
> >Normally, if the PSU connector goes high resistance, it overheats and the
> >plastic turns brown. It's easy to spot...
>
> Erm, it *is* brown - but a nice factory brown, and it's not slightly
> crumbly or showing any signs of discolouration...
>
> >
> >> however, moving it around would have no effect.
> >>
> >> Is there any way to test for a drying cap?
> >
> >YEs, you need an ESR meter (or a good impedance bridge). The former is
>
> ESR?
>
> >not too expensive (around 50 quid, especially if you buy it as a kit),
> >and is probably worth getting if you get seriously into doing repairs
> >(particularly of switch-mode PSUs). The latter is expensive, and is only
> >worth getting you do a lot of design (or research :-)), or if somebody
> >gives you a broken one (as happened to me...)
>
> :) I shall live in hope...
>
> >
> >[Stewarts]
> >
> >> No harm in asking... I may drive out on Saturday and have a look, if
> >> they're open.
> >
> >I can't remember if they open Saturday mornings. I am pretty sure they
> >close in the afternoon.
>
> I've actually had a couple of offers of 'scopes (thanks, chaps), so I shall
> see what becomes of those first.
>
> >
> >[Logic analysers]
> >
> >> GBP500 is reasonable,
>
> (actually, this referred to *all* test kit, not just an LA)
>
> >>I'd say, so long as the kit is going to last a while
> >> and do most of the stuff I need of it. I can always sell it on later, of
> >> course, when/if I need to upgrade.
> >
> >It depends on what you want to do. If you are going to work mostly on
> >classic stuff then a 100MHz 16 channel analyser should be enough (it'll
> >be useful on all 8 bit micros, PDPs (8s, 11s, 10s, etc), older VAXen, and
> >so on. If you are intending to do some designing with the latest chips
> >then you might need something faster in the end.
>
> For now, I don't see myself working with the latest & greatest; I've only
> got one duff PET at the moment, although if I can get this one running
> again, I may more actively seek broken kit, if only for practice.
>
> However, whilst I like the idea of learning embedded systems, I'll probably
> start simple and use a Z80 or similar - I can't (yet) think of anything
> where I'd use some super-fast chip. Incidentally, what's with these PIC
> chips? They seem to be very popular at the moment.
>
> >> What about one of these software oscilloscopes? I think the only one I've
> >> seen was a picture on EPE's website, but there must be a few of them
> >> surely? Mind you, hardly a portable device if you need a pentium PC within
> >> reach...
> >
> >I'd not bother with them. They are not exactly convenient to use (and you
> >have to get a PC to put them in (or at least I would...). They are
> >digital sampling storage scopes (which is nice), but I suspect a good old
> >analogue scope is more useful to you at the moment.
>
> I tend to agree. I could use a parallel-port device relatively easily (I
> have a couple of laptops), but space is of a sufficent premium here that it
> would genuinely be easier to have a self-contained device.
>
>
> Cheers!
> Ade.
> --
> B-Racing: B where it's at :-)
> http://www.b-racing.co.uk
>
>
Received on Fri Aug 24 2001 - 04:35:26 BST