25 Jan
2015
25 Jan
'15
6:42 p.m.
On Jan 25, 2015, at 6:06 PM, Barney Wolff <barney@databus.com> 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.