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A Kenbak-1 at the Computer History Museum
DeveloperJohn Blankenbaker
ManufacturerKenbak Corporation
Typepersonal computer
Release date1971; 50 years ago (1971)
Introductory priceUS$750 (equivalent to $4,793 in 2020)
Discontinued1973 (1973)
Units sold40
Units shipped40
Memory256 bytes of memory

The Kenbak-1 is considered by the Computer History Museum and the American Computer Museum[1] to be the world's first "personal computer",[2] invented by John V. Blankenbaker (1930-) of Kenbak Corporation in 1970, and first sold in early 1971.[3] Only 50 machines were ever built using Bud Industries enclosures as its housing per the Oral History of John Blankenbaker. The system first sold for US$750.[4] Today only 14 machines are believed to exist worldwide,[5] in the hands of various collectors. Production of the Kenbak-1 stopped in 1973[6] as Kenbak failed, and was taken over by CTI Education Products, Inc. CTI rebranded the inventory and renamed it the H5050, though sales remained elusive.[7]

Since the Kenbak-1 was invented before the first microprocessor, the machine didn't have a one-chip CPU but instead was based purely on small-scale integration TTL chips.[8] The 8-bit machine offered 256 bytes of memory,[9] implemented on Intel's type 1404 silicon gate MOS shift registers.[10] The instruction cycle time was 1 microsecond (equivalent to an instruction clock speed of 1 MHz), but actual execution speed averaged below 1000 instructions per second due to architectural constraints such as slow access to serial memory.[8]

The machine was programmed in pure machine code using an array of buttons and switches. Output consisted of a row of lights.

Internally, the Kenbak-1 has a serial computer architecture, processing one bit at a time.[11][12]

See also[edit]

  • Datapoint 2200, a contemporary machine with alphanumeric screen and keyboard, suitable to run non-trivial application programs.
  • Mark-8 The Mark-8 was designed by graduate student Jonathan A. Titus and announced as a 'loose kit' in the July 1974 issue of Radio-Electronics magazine.
  • Altair 8800, a very popular 1975 microcomputer that provided the inspiration for starting Microsoft.


  1. ^ "The George R. Stibitz Computer Pioneer Award". Archived from the original on September 13, 2008. Retrieved August 5, 2008.
  2. ^ "Timeline of Computer History". Computer History Museum. Retrieved July 22, 2008.
  3. ^ BBC News, November 6, 2015
  4. ^ "Kenbak-1 The Training Computer". Computerworld. November 17, 1971. p. 43. Retrieved May 25, 2014.
  5. ^ "Kenbak-1". Computer Museum of Nova Scotia. Retrieved 19 November 2015.
  6. ^ p. 52, "The First Personal Computer", Popular Mechanics, January 2000.
  7. ^ Robert R Nielsen, Snr (2005). "Inside the Kenbak-1". Retrieved 8 November 2015.
  8. ^ a b Erik Klein. "Kenbak Computer Company Kenbak-1". Retrieved May 25, 2014.
  9. ^ Bill Wilson (6 November 2015). "The man who made 'the world's first personal computer'". BBC News.
  10. ^ "Technical".
  11. ^ "Kenbak Theory of Operation Manual". p. 16.
  12. ^ "Official Kenbak-1 Reproduction Kit".

External links[edit]