IBM 1620; was: Early Programming Books

William Donzelli wdonzelli at
Mon Jun 21 16:26:51 CDT 2021

> Of course, nowadays, the old R22 systems are being refilled with
> purified propane, called R290.  Cheap, with better thermal properties
> than R22, but probably not legal when LCM picked up the 6500.

When cleaning out a 3rd party CDC dealer quite a few years back, he
remarked that the CDC machines going way back all the way to the 800s
were fantastically unpicky about how they were cooled. He just used a
garden hose connected to the building potable water, and if the
machine under test needed more coolant because it was running warm, it
just pumped more supply. Heated waste water went down the drain.

This unlike the IBM water machines.


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