New to the List -- Criteria for Being Salvageable? -- Query

Tony Duell ard at p850ug1.demon.co.uk
Tue Mar 8 13:23:52 CST 2011


> 
> Hello fellow classic computer enthusiasts. I'm quite new to the list,

Hello, and welcome ot the list.

> but an avid fan of all things "retro" computerwise. Though, at present
> I don't have anything that could be described as a "classic" system
> beyond a KSR-33 teletype made by Leigh up here in Canada sometime
> during the 60s or 70s.

That's a good start :-)

> 
> Now, on to what the main thing I wanted to discuss...
> 
> I'm a student at Brock University in southern Ontario, and I've
> noticed that the faculty of computer science has a small collection of
> quite vintage machines; from what I remember there's a "classic"
> PDP-8, a PDP-8/L and an HP2116 I think. They also have a nice ASR-33
> teletype in the collection, as well as various other tidbits.
> 
> So, my question is what would the criteria be to be able to make those
> systems capable of being run once more? From a cursory visual

I would suggest the following as being useful/necessary

1)  A failry complete example of the machine you care goign to restore. 
Missing parts are mucnh more of a problem than defective parts IMHO. If 
all the PCBs are there, it's a good start

2) Spare parts. It's actually amazing how may of the spares I need for
classic computers are still very easy to get. The sort of machines you
mention are not goign to be too ahrd to get parts for -- at the component
level, of course. It's a lot easier to get spares for a 1970's
minicomputer than fro a 1990s PC. 

3) Information : DEC manuals, printsrets (scheamtics), etc are often 
available from bitsavers. I don't know if the HP2116 hardware 
documentation is on the Australian musesum site. If you can't get 
scheamtics, you have to spend many, many, days reverse-engineering the 
machine. This is somethign I would only recoemnd tryign if you are (a) 
knowledgeable aobut how CPUs work at the gate level (in genral) and (b) 
insane

4) Somebody (or group of people) who are willing to put the time in. 
Restorign a minicomputer is likely to take some time, particularly if 
it's the first time you've ever senbe a CPU that wasn't a single chip. On 
the otehr hand, you'll learn alot from doing it (although how useful this 
is is, alas, debatable).


> inspection, the PDP-8 appears to be complete, FLIP-CHIP wise, the
> PDP-8/L is enclosed but dusty, and I think the HP - which is open -
> has a pretty nice loadout of cards. So going by modules I would say
> all the hardware is there (save power supplies?), so what would be
> needed to bring up one of those systems?
> 
> And more importantly, would any one be interested in signing (an
> online) petition to the BrockU CS Faculty to convince them to try and
> restore one of their minis and their terminal back into a functional
> state?

I think there's a lot more (educational) value in getting the amchine 
running than in actually using it once it's restored. It seems to me 
that there's no much differnce between running a program on a real PDP8 
and on an emulator, for example. But actually getting into the hardware 
with 'socpe and logic analyser, that will teach you a lot.

I don;t know if your university would allow this, and I don't know if 
there's a group of enthusiasts there know to the faculty as being 
somewhat clueful. If so, would it be possible for you (and others) to do 
the restoration under some kind of supervision (to make sure you didn't 
electrocute yourtsleves or worse wreck the machine)? I would certianly 
want to encourage that sort of thing.

-tony



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