Availability, Fire Safety, and the IBM 704

The SHARE organization was organized in 1955 to share operational knowledge and computer programs for operators of the IBM 704. “Operational knowledge” included monthly availability reports and, perhaps unexpectedly, safety advice.

Each site reported its own availability via a common form. Each installation was given a two-letter identifier (which, as SHARE grew to more installations, became a branding problem for some sites). The NS site was a government-run facility. This is a typical report from them:

The NS site reported some of the highest availability scores; a 93.6% score was very good, comparatively, particularly since it was over multiple shifts. Compute time covered the actual productive use of the computer, while checkout represented time spent in development and testing activities.

The RAND Corporation sold some of the computer time to other customers. This report from July shows only a small fraction of time sold to other customers (“Good Time”), but other months showed higher percentages. RAND seemed to struggle with availability as they were usually below 80%. Based on my review, the various sites seemed to average 80%.

The most interesting report was this one from RAND in May of 1956:

The footnote “Main frame fire” was elaborated in a letter from Irwin Greenwald that also provides some useful fire tips: