Happy 50-th Anniversary, APL

[Roger|Dyalog]

In honor and in celebration of the 50-th anniversary of APL:

A History of APL in 50 Functions
Some Exercises in APL Language Design

It was Sunday, November 27, 1966, the Thanksgiving holiday weekend in the United States. But the APL implementers were working. The fruits of their labor were recorded for posterity:

      )load 1 cleanspace
SAVED 1966-11-27 15.53.59 (GMT-7)

1 cleanspace had a saved timestamp that was carefully preserved from one release to the next, from one version to the next, from one APL to the next.

The time is actually off by 1 second. As Dick Lathwell recounted:

Trivia trivia: The timestamp on 1 cleanspace is actually 1 second later than the original. Some time after the implementation of )clear, Adin dropped 1 cleanspace. He then had second thoughts, so I set the time and date of the model 50 to the original timestamp with the clock disabled and started APL and entered )save 1 cleanspace. The implementation of our supervisor (I guess these days we would say kernel) was such that an interval timer interrupt was required to enter the scheduler, so I momentarily enabled the clock.

For more stories from that time, see The Socio-Technical Beginnings of APL.