vintage computers in active use

Eric Smith spacewar at
Fri May 27 01:30:22 CDT 2016

I wrote:
> Another CHM volunteer (from the PDP-1 Restoration Project) and I
> pushed for an IBM 360/30 Restoration Project, and the ability to build
> replacements for failed SLT modules was part of our plan.

On Thu, May 26, 2016 at 9:40 PM, William Donzelli <wdonzelli at> wrote:
> I am still trying to figure in which universe are SLT modules so rare
> that one needs to fabricate replacements.

As far as I can tell, if I suddenly need a specific SLT module, the
odds of finding that specific module at any given time on eBay is
essentially zero.

Obviously if we could find an authentic replacement, we'd prefer that.
We didn't want the entire restoration to be dependent on having to
find authentic replacements.

Some SLT modules are far more common than others. I don't know how
many different SLT modules are used in the 360/30, nor what percentage
of the SLT modules in that machine are common ones.  When we restored
the DEC PDP-1, it contained quite a few DEC System Modules from DEC's
standard catalog and that we had spares of, but it also contained a
non-trivial number of specialized modules that are much harder to
find, if not impossible. I'm guessing that IBM machines were probably

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