IBM 1620

IBM 1620
IBM 1620 Model I, Level H
ManufacturerIBM
TypeScientific minicomputer
Release date1959
Units shippedAbout 2000
CPUTransistorized, built with SMS cards, variable 12-72 bit words @ 50 kHz (20 us)
Memory20,000-60,000 words (Core memory)
Power2 kW
Mass550 kg (1210 lbs)
PredecessorIBM 650; IBM 610; IBM 608
SuccessorIBM 1130
RelatedIBM 1710, IBM 1720
IBM 1620 data processing machine with IBM 1627 plotter, on display at the 1962 Seattle World's Fair

The IBM 1620 was announced by IBM on October 21, 1959,[1] and marketed as an inexpensive scientific computer.[2] After a total production of about two thousand machines, it was withdrawn on November 19, 1970. Modified versions of the 1620 were used as the CPU of the IBM 1710 and IBM 1720 Industrial Process Control Systems (making it the first digital computer considered reliable enough for real-time process control of factory equipment).[1]

Being variable-word-length decimal, as opposed to fixed-word-length pure binary, made it an especially attractive first computer to learn on – and hundreds of thousands of students had their first experiences with a computer on the IBM 1620.

Core memory cycle times were 20 microseconds for the (earlier) Model I, 10 microseconds for the Model II (about a thousand times slower than typical computer main memory in 2006). The Model II was introduced in 1962.[3]

  1. ^ a b "1620 Data Processing System". 23 January 2003. Archived from the original on January 14, 2005.
  2. ^ "Some Key Dates in IBM's Operations in Europe, the Middle East and Africa (EMEA)" (PDF). Archived from the original (PDF) on 2022-10-10.
  3. ^ "The IBM 1620: Just The Right Machine for Chula's Statistics Department". Archived from the original on 2017-12-22. Retrieved 2017-12-20.