REMINDER: Leap Second

TR Shaw tshaw at
Sun Jan 25 23:42:51 UTC 2015

On Jan 25, 2015, at 6:06 PM, Barney Wolff <barney at> wrote:

> 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.

That made the transformers smaller/cooler and more efficient. I seem to remember a 195 as well but maybe it is just CRS.

More information about the NANOG mailing list