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What was the first personal computer?

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Click here for further information on our rarity scale RARITY: Exceedingly Rare Information on the rarity of this item is unknown.

 YEAR: 1967

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Computer Trainer Model 650

A view of the vintage Computer Trainer Model 650 an important part of computer history
Developed by Irving Becker, who unfortunately died December 2005, the CT-650 was one of the earliest digital personal computers. The CT-650 is likely one of the earliest digital personal computers ever made. One could make the argument that it was the first. (Depends on how you evaluate the Minivac-601 and Minivac-6010).

Updated Oct. 2019): We are tentatively dating this computer to 1967 based on indirect evidence. The Comspace Corporation was granted a copyright for a "General Operating Manual for Arkay CT-650 computer trainer" on June 22, 1967.1 The manual is described as being for an "Arkay CT-650 desk-top computer trainer". What strikes me as odd about this is that the book upon which this computer is supposedly based was also published in 1967. Would Mr. Becker have had time to put together an operating manual?

By the 1960’s he was developing many educational products including the Computer Trainer-650 and a cardboard kit for Bell Laboratories called “CARDIAC” (a reference to its cardboard construction and the names of other kits like Brainiac and Geniac).

Irving was dedicated to education and even made a special version of the CT-650 that was made for blind students. Aside from Braille lettering, the bulbs under each light were extra strong so as to generate more heat…that way the student could “read” the results by feeling which lights were lit.

The CT-650 is sometimes called the "paperclip computer" which is a reference to a 1967 book entitled How To Build A Working Digital Computer. The book describes how to make a computer out of things one might find around the house...such as tin cans, screws, paperclips and even wooden spools of thread. The design of the CT-650 seems to have relied on the book's plans and, therefore, it is called the "paperclip computer".

The computer is 54" in length by 22" in depth. It was built for educational use with six clearly labeled sections:
  • Core Memory
  • Program Drum
  • Input Unit
  • Arithmetic Unit
  • Control Unit
  • Output Unit.
Some sources list this computer as the Arkay CT-650. The company name on the computer itself is Comspace not Arkay. But the copyright for the operating manual refers to the computer as the Arkay CT-650. Like many who were involved with early computers, Irving Becker started off in radio. In 1945, he began selling radio kits (the original name of his company was “Arkay” which stood for the “R” and the “K” in “radio kits”). By the time that this computer was offered he was in the process of changing the name of the company from Arkay to COMSPACE.

At some point before July 1980, Comspace Corporation moved from Brooklyn to Farmingdale, Long Island.

1According to the Library of Congress' Catalog of Copyright Entries: Third Series, Volume 21, Part 1, Number 2, Section 1 on page 1,690 (God bless the LOC for keeping track of information!) copyright #A925698 was issued to Comspace Corporation.

Viewer Stories & Comments
   William Berson     Westport, USA     December 29, 2020

       RE: Arkay CT-650 Computer th I have some first hand knowledge of this early device, as my first (summer ) job during high school and college was to write the first programs for it and to do the production engineering for its manufacture. I knew Irving Becker and his family well. The mystery concerning the "how to build a working digital computer book" is simple. The CT-650 was copied from the design in the book. As a matter of fact the author sued Becker and Comspace on that basis, unsuccessfully.... with the judge ruling that as the CT-650 was not a kit and not made of paperclips, etc. it did not infringe. I (and Becker's son Nelson), carried the first CT-6t50's around the country, making the rounds of potential customers and tradeshows in the education market in the mid 1960's, with me demonstrating that even a high schooler could use it. As the book described, it was not a computer at all, but rather a manually operated simulator of a 1401 basic configuration, There was no processing capability, but the input and output sections were hardwired to convert decimal switch digital settings to a lighted binary number display and visa versa. These sections were borrowed from the design of various A/D and D/A trainers that were already on the market (by others) prior to Comspace's offering. The 'memory drum', was an aluminum cyinder with spring steel contactors which could read holes in a mylar sheet that represented various instructions ain a program. The instructions served only to light indicator lamps which cued the operator on how to transfer various 4 bit numbers around the machine. The arithmetic section was also hard-wired to add 4 bit numbers via SPST switches and indicator lamps. In all, less than 100 were made, but the unit was a success in bumping up Comspace's stock on the NASDEC. Uncredited in the published history of this saga, is Fred Barrett, who was the chief engineer of Comspace and who, I believe, designed the details of CT-650. Barrett, a black man, by the way practically single-handedly engineered Comspace's products. Irving Becker was a man of vision and intelligence, and kind to a young kid who was a computer geek, before the word had been invented.

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Click on any of the images below to see the slideshow. Front view of the CT-650. That is one long computer! Encoder and Arithmatic sections close-up of Arithmetic section Close-up of the control panel. Close-up of the decoder or output section The programming section This core memory section Programming section Close-up of a program sheet The Comspace with some analog computers in the background.
(Analogs in blue)
  1. AIM-65 (single board)
  2. AIM-65 (factory case)
  3. AIM-65 (Jon Titus)
  4. ALICE micro-ordinateur
  5. Altair 680
  6. Altair 8800
  7. Altair 8800A
  8. Altair 8800b
  9. Altair 8800b Turnkey (see Pertec below)
  10. Altair 8800b (see Pertec below)
  11. Altair 8800b w/ Hardisk Controller & Datakeeper
  12. Altos ACS-8000
  13. American Basic Science Club Analog Computer
  14. AMF Educational Computer
  15. Apple II Plus
  16. ASCI SystemX
  17. ASR 33 Teletype
  18. Automatic Teaching Computer Kit
  19. Beckman ElectroComp Electric Heating Computer
  20. Beckman ElectroComp Energy Savings Computer
  21. Beckman Solid State Fuel Cost Computer
  22. Brainiac K-30
  23. Calif. Computer Systems 2200
  24. CES Ed-Lab 650
  25. Commodore 8032
  26. Commodore 64
  27. Commodore PET 2001
  28. Commodore Super Pet
  29. Compucolor II
  30. Compukit 1
  31. Compukit 1 Deluxe Model
  32. Compukit 2
  33. Compukit UK101
  34. Comspace CT-650
  35. Cosmac Elf (RCA1802)
  36. Cosmac Microtutor
  37. Cosmac Netronics ELF II
  38. Cosmac VIP
  39. Cromemco System I
  40. Cromemco System III
  41. Cromemco Z-2D
  42. Datapoint 2200
  43. Digi-Comp I (flat box)
  44. Digi-Comp I (square box)
  45. Digital Computer Lab
  46. Donner 3500
  47. Durango F-85
  48. Dynabyte
  49. E & L Inst MMD-1
  50. E & L Inst MMD-2
  51. Eagle II
  52. Electric Tabulating Machine (one original counter, 1889)
  53. Electronic Associates TR-10
  54. Electronic Associates TR-10 Model II
  55. Electronic Associates TR-20
  56. Electronic Associates TR-48
  57. Electronic Associates Model 180
  58. Electronic Associates Model 380 Hybrid
  59. Geniac
  60. Google Glass (definitely not vintage)
  61. Heath EC-1 (factory assembled by Heath)
  62. Heathkit EC-1 (kit)
  63. Heathkit ET 3100 trainer
  64. Heathkit H8
  65. Heathkit H9 Video Terminal
  66. Hickok Logic Teaching Sys.
  67. Hickok Servo Teaching Sys.
  68. HP 2115A
  69. HP 85
  70. HP 5036A
  71. HP 9825A
  72. HP 9825B
  73. HP 9830A
  74. Iasis 7301
  75. I-COR MAC-1
  76. ICS Microcomputer Training System
  77. IMSAI 108 (prototype)
  78. IMSAI 8048 Control Computer
  79. IMSAI 8048 (The Dollhouse Computer)
  80. IMSAI 8080
  81. IMSAI PCS-40
  82. IMSAI PCS-80
  83. IMSAI VDP-80
  84. Informer
  85. Intel Intellec MDS
  86. Intel MDS-800
  87. Intel Prompt 48
  88. Intel SBC 80/10
  89. Intel SDK-85
  90. Intel SDK-85 (unassembled)
  91. Intel SDK-86
  92. Intertec Superbrain
  93. ITT MP-EX
  94. JR-01 Computer
  95. KIM-1
  96. LAN-DEC
  97. LAN-DEC 20
  98. LAN-ALOG
  99. Lehrcomputer (Germany)
  100. Lawrence Livermore Lab
  101. Lear Siegler ADM3A
  102. Logikit LK255 (Feedback)
  103. Logix SF-5000 Electronic Computer
  104. MAC-1 Mini Analog Computer
  105. MAC Tutor (Bell Laboratories)
  106. MEK6800D2
  107. Micro 68
  108. Microtan 65
  109. Midwest Scientific Instruments 6800
  110. Minivac 601
  111. Minivac 6010
  112. Mini-Scamp Microcomputer
  113. Nascom I
  114. Nascom II
  115. National Radio Institute 832
  116. NEC TK-80
  117. NorthStar Horizon
  118. Olivetti Programma 101
  119. Olivetti Programma 203
  120. Olivetti Programma 602
  121. Open University PT501
  122. Ordinateur d'Apprentissage JR-01
  123. Osborne 1
  124. OSI 300
  125. OSI 600 (SuperBoard II)
  126. OSI C2-OEM-4
  127. OSI Challenger-1P
  128. Pastoriza Personal Analogue Computer
  129. Pertec MITS 300/25 (Altair desk business system)
  130. Pertec MITS 300/55 (Altair Turnkey business system)
  131. PolyMorphic Systems 8810
  132. PolyMorphic Poly-88
  133. Protech-83
  134. Range Keeper Mk.6 Mechanical Analog Computer, 1926
  135. Range Keeper Mk.7 Mechanical Analog Computer, 1935?
  136. Sargent-Welch Scientific Company Cat. No.7528 Analog Computer
  137. Science of Cambridge MK-14 (Sinclair)
  138. SD Systems Z80 starter kit
  139. Sharp MZ-40K
  140. Sharp MZ-80k
  141. Siemens ECB-85
  142. Signetics Instructor 50
  143. Sinclair ZX-81
  144. Smoke Signal Broadcasting
  145. Sol-20
  146. Spark16
  147. Sphere 1
  148. Sphere/SWTPC Computer System
  149. SWTP CMOS Microlab
  150. SWTP CT-82 Terminal
  151. SWTPC 6800
  152. SWTPC 6800 (w/ Smoke Signal Broadcasting drive)
  153. SWTPC CT-64 Video Terminal, SS-50
  154. SWTPC TV Typewriter II CT-1024
  155. Synertek VIM-1
  156. Synertek SYM-1
  157. Systron-Donner 3500
  158. Tei MCS-112
  159. Tektronix 4006-1
  160. Telefunken RAT 700
  161. TI LCM-1001 (Microprogrammer)
  162. TI LCM-1001 (Microprogrammer)
  163. TI Silent 700 Terminal
  164. TI TM 990/189
  165. Vector 1
  166. Vector 3
  167. Vidac 336
  168. Wang 2200
  169. Welch Scientific Company Cat. No.7528 Analog Computer
  170. Xerox 820 Mark I
  1. Chameleon Plus
  2. Commodore SX64
  3. Epson HX-20
  4. Kaypro I
  5. Kaypro II
  6. Kaypro 2x
  7. Kaypro 16
  8. Osborne 1
  9. Panasonic Senior Partner
  10. Visual Commuter
  1. Babbage's Calculating Engine (1834)
  2. Electric Tabulating Machine (1889, Herman Hollerith's personal copy)
  3. The Hollerith Electric Tabulating System (1890)
  4. Counting a Nation by Electricity (1891)
  5. Calculating Machines (1947)
  6. Moore School Lectures Vol. II (1947)
  7. Mathematical Theory of Communication (1948)
  8. Communication Theory of Secrecy Systems (1949)
  9. The "Moore's Law" article (Electronics, 1965)
  10. Printout from Babbage's Difference Engine #2 (London Science Museum, 2004)