vintage computers in active use

Jon Elson elson at
Fri May 27 20:53:20 CDT 2016

On 05/27/2016 11:45 AM, William Donzelli wrote:
>> OK, where can you buy some?
> You ask the community. You ask on the list or elsewhere. "Hey, I need
> a 361459. Anyone have one?".
>> They haven't been made since about 1970.
> But in those six or seven years - wow, did they make a lot of them. In
> Binghamton, we have some of those dumb desk ornament things that suits
> like to hand out. One of them is has the 100 Millionth (!) SLT module
Yes, IBM was cranking out SLT at an absolutely amazing 
rate!  In fact, before there was Silicon Valley, upstate New 
York was a huge technology center, and most of it was 
churning out all the myriad assemblies of IBM 360 systems, 
processors, channels, memory, peripherals, etc.
> (OK, we know that being a dumb desk ornament, they probably made some
> number of 100 Millionth SLT module, but the point is clear). Oh, and
> the desk ornament is dated fairly early in the game!
>> IBM
>> sent out a letter to all 360 users who had machines under contract, giving a
>> date when they would no longer guarantee that any particular machine could
>> be repaired, due to lack of spare modules, and a second (later) date when
> Typical IBM.
Well, it was pretty much commanded by the US government.  
Remember, they had to keep 360s running until 1989!  YIKES!  
(Although I'm sure at the time they had no idea the 
replacement would drag on for that long.)
> SLT and S/360s did indeed have teething problems. It took 
> a while to get the bugs out of the system. 
Yes, but I'm sure once they DID get manufacturing of of SLT 
working, they had a way to make lots of logic at a cost much 
lower than all the other computer makers who were still 
stuck with little metal-can transistors and glass diodes on 
PC boards.
>> But, I'll bet that oxygen and moisture will continue to take their toll at a
>> slower rate.  Remember, all this gear is now about 50 years old!
> IBM SLT cards and modules seem to do well - I have picked up more than
> a few that were exposed to the elements, and if they are not beaten up
> (curse those crappy thin aluminum covers they used!), moisture tends
> to not be a big issue, thanks to the silicone goop underneath.
I looked at some stuff from the disk lab in Rochester, MN. 
(I think) that was given to Washington University some years 
ago.  It had all been stored in good conditions.  WU wanted 
the air bearing fixtures and a few other things, but had no 
interest in all the gear that ran it, Series/1 and racks of 
SLT boards.  Some of the aluminum covers could be flicked 
off with your fingernail..The green epoxy that held them on 
had started to go bad, I guess.

Some of the guys who reported earlier on 1800 systems seemed 
to think they were a LOT more reliable than my experiences 
watching 360/50 and 360/65 reliability.  It might be that 
the 1800 had shorter stacks of boards to be cooled in the 
same airflow.  I know the /65 had a tall stack, and some of 
the areas of the CPU had pretty hot air coming out the top.


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