My First Program

This is the first computer program I ever wrote that was actually run on a computer. It’s written in CESIL, a teaching language provided by ICL and used in the first year of the’O’-level Computer Studies course.

After some weeks learning about algorithms by drawing flowcharts and then being introduced to the CESIL language by writing code in our exercise books, it was finally time to run a program on a real computer - the local college’s small ICL 1900 mainframe. It happened like this:

  1. Our teacher set the programming problem as homework.
  2. In the next lesson, we brought back our programs written on coding forms like this. Note that the coding sheet has fixed fields for identifying the school and the pupil:
Photo of a completed CESIL coding form
  1. That evening, the teacher would take all the coding forms up to the local college.
  2. The computer centre staff would punch the programs onto punched cards.
  3. All of the CESIL programs submitted by different schools using the college computer would be batched together into one deck of cards. When the next CESIL run was scheduled, the batch of cards would be fed into the card reader, generating line printer output. This would then be split into sections, one for each school.
  4. Our teacher would then collect our results ready for our next lesson. Here’s what I got back:
Photo of the printout from a CESIL program

This is the process we would follow for the rest of the two years of the ‘O’-level computer studies course writing CESIL and BASIC programs both for homework and for the project work we needed to submit as part of the exam.

With turnaround times of a week per run, my three ‘O’-level projects would only get around half a dozen runs each and so a lot of time was spent manually “dry-running” them with pencil and paper to make sure they worked first time if at all possible.