EDSAC workflow on film, 1951

Maurice Wilkes presents this short film explaining the preparation and running of programs on EDSAC:

Via the HNF blog’s piece all about perforated tape media:
Holes in the strip (in German)

In which we see that Zuse’s machines executed loops like this:

(See also a patch, and a library.)



  • Enter the program as a long paper tape
  • Mathematical functions etc. are subroutines existing on small rolls of paper tape. Pick the ones you need from the library, which is a physical place with rolls of paper tape, one for each subroutine
  • Copy the subroutine tapes into your program tape at the appropriate spots
  • Make another tape and compare with the first one, just to catch typing errors
  • Hang the finished program(me) in the job queue! Now that’s a proper job queue!
  • When your job reaches the first spot in the queue, pick the tape and insert it into the reader
  • Execute!
  • The output is printed on a sheet of paper, dropped into the output box

Enjoyed the film! I got to see Maurice Wilkes in person when he visited the University of Washington, must have been sometime in the seventies when I was in graduate school in computer science. He was just as engaging then as in the film. Thanks for sharing that.

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