25 May
2003
25 May
'03
3:55 a.m.
In message <m19Jhi9-000IyHC@p850ug1>
ard(a)p850ug1.demon.co.uk (Tony Duell) wrote:
I can't see why either - if they used valves (vacuum tubes), the
tubes
should still be available NOS or used, same for the valve bases. If the
bases had been smashed, a schematic would be damn useful.
If it's transistor based, I'd just trace the circuit...
> Over the
years how many people are still around who can
> operate, repair, or maintain 50's era computers? Power requirements would
Can somebody please explain to me why it is so difficult to _learn_ these
skills? I will admit I've enver worked on a 1950's computer (the oldest
machine I've worked on dates from 1969 [1]), but I don't see why I'd find
it impossible given a little bit of time to learn the tricks that were
used then. [1] An HP9100B. I had to start out by writing the
repair manual...
The oldest machine I've worked on... Hmm... That's a tough
one... I guess
that would be the Jupiter Cantab "Ace" computer I'm restoring^W rebuiling.
[mental note: cover the unused connectors on the PSU with electrical tape
BEFORE powering up].
The one thing that never ceases to amaze me about the Ace is just how lousy
the tin plating on the board really is. I've touched my soldering iron to
various tracks on the board and the tin plating has come right off!
Either the flux in my roll of Multicore 60-40 solder is doing this or the
tin plating wasn't put on right. The board underneath the plating has
oxidised quite a bit... Continuity is still OK after a good cleaning, but
it's still a pig to find out that a bit of solder has separated from the
board simply because the tin plating is fubar'd.
It's interesting that a small private computer
history group that I
belong to states its aims as 'preserving old computers, programs, methods
and operating practices as far as possible'. Clearly they think (as do I)
there's more that need to be preserved than just circuit boards :-)
Yup.
I'm planning to make a backup copy of my Jupiter Ace tape and then use
the backup. One digital copy on the PC (44100Hz mono), one analog (tape)
copy. Then the fun of decoding the tape image and rebuilding the digital
data begins...
Now, if only I could get the Ace working... Is anyone here placing an order
with BGMicro in the near future? I need some more RAMs to keep as spares
for the Ace and my Cosmac Elf (DIY'd too - there's a picture of it on
www.cosmacelf.com).
That is, unless someone knows of a company in the UK that can supply 2114s
and 2101s... A CDP1861 (RCA Pixie graphics controller) would also be quite
useful... Then again, I've heard the 1861 has a pretty good reliability
record - supposedly much better than a 2114 RAM...
Later.
--
Phil.
philpem(a)dsl.pipex.com
http://www.philpem.dsl.pipex.com/