IBM System/38 Available for Free, Is It Worth It?

From: William Donzelli <william_at_ans.net>
Date: Sun Sep 21 21:57:06 1997

> Well, I can hardly talk (I have about 20 DEC minicomputers of assorted
> flavours) and no IBM minis at all, but the main reasons for this are :
>
> 1) First and foremost, I've not been offered any. Obviously I can't
> collect what I can't find. Seriously, if I was offered a _small_ IBM mini
> that otherwise wouldn't be saved, I would rescue it (the _small_ is due
> to a lack of space only). I did buy an RS6000 at a radio rally (hamfest)
> earlier this year.

People are abandoning System/36 boxes like crazy these days. If you
search, you should be able to find a deskside system for free in little
time.

> 2) But the main thing that keeps me away from IBM machines (and towards
> DEC/Philips/etc) is that IBM machines are often almost impossible to hack
> and repair. The chips are those strange IBM square metal cans with
> unlisted numbers. Schematics and spares are impossible to obtain. A
> binary listing of the instruction set is sometimes a pain to find. The
> releasing of the full TechRef for the first PC was something of a suprise
> to hackers used to IBM's behaviour in the past.

You do have a valid point, IBM does things weird. The chips are far from
off-the-shelf. The solution is to build up spares from donor machines. For
my RS/6000s, I saved some extra motherboards (planars, as they call them).
For System/3x stuff, there seem to plenty of machines in the scrapyards
that can be picked apart. IBM tended to cram lots of stuff in a small CPU
box, situated inside the normally spacious cabinet. Pulling an entire CPU
should pose no problems. Even if one had a big machine, like a 3081 (a
water cooled monster, probably not too collectable), the actual meat of
the system (the TCMs - Thermal Conduction Modules) would fit in a small
carton.
 
While the pre-VAX DECs are very easy to hack and repair, do the later ones
not also suffer from the custom parts problem? I just packed up a module
set for a VAX 11/750, with all of those VLSI gate arrays. The best thing
for repair is to get donor boards. And even some of the standard chips on
the boards can be bears to find (looking at the F100K ECL on the disk
controller - how many times have you seen F100K glue logic available?).

Schematics, I agree, are a problem.

> Now, a manufacturer that _never_ seems to get mentioned is Philips. How
> many people realise that Philips (yes, the company that also makes
> consumer electronics, etc) made minicomputers. They certainly made a
> series of 16 bit machines in the 1970's, and I've heard of machines using
> valves (tubes) back in the 1950's also from Philips.

I remember seeing some ads in some 1970s era issues of *Electronics*. I
have never seen one, I suppose very few made it overseas.

William Donzelli
william_at_ans.net
Received on Sun Sep 21 1997 - 21:57:06 BST