REMINDER: Leap Second

Barney Wolff barney at
Sun Jan 25 23:06:49 UTC 2015

On Sun, Jan 25, 2015 at 02:24:52PM -0800, Stephen Satchell wrote:
> Today's computers don't use clocks derived from 50- or 60-hertz
> power-line frequency.  The last computer I remember seeing with such a
> clock was the IBM System/360.  The System/370 used a motor-generator set
> for the power supply, so it had to get its real-time clock time source
> another way.

The 360/95 and /91 also used 400 Hz from a motor/gen.  Water cooled, too.
One of my fondest war stories is when the power was turned off for July 4th
weekend but the water was left on.

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