From: David Forbes
I was reading that 1961 BRL survey, and found the user reports
of the IBM 701 fascinating. They apparently had an average
uptime of about 2-4 hours.
In 1976 I worked with a guy who maintained a tube computer when he was going
to Cal Poly San Luis Obispo. He said that everyday the ran a diagnostic at
low voltage then at high voltage. This would point out weak tubes. They
would replace the tubes and the machine was good for another day.
Michael Holley
www.swtpc.com/mholley