The PTERA (PTT Electronische Reken-Automaat or in English: PTT Electronic Calculating Machine) was the first real computer that Kosten and Van der Poel built at the PTT. With the experience gained in building the ZERO which was finished in 1952, they started working on the PTERA, which they finished in September 1953.

There was a limited budget to work with, and there was a considerable pressure to get the machine operational as fast as possible, so there was no time to work out the design carefully. Van der Poel called it "a weird machine" that wasn't really innovative or creative. Nevertheless the machine was used at the PTT for some years[1][2].


  • Finished in 1953
  • Used at the PTT for several years
  • Calculating power comparable to the ENIAC, but slower
  • 700 Vacuum tubes used and 120 relays, compared the the ENIAC's 18000 vacuum tubes this was very few.
  • Memory: A magnetic drum with a capacity of 1024 words of 31 bits each.


  1. Kranakis, E. , "Early Computing in the Netherlands", CWI Quarterly, vol. 1, issue 4, pp. 61-84, 12/1988.
  2. Poel, W. van der , Een leven met computers, , 1988  .
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