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[[File:Kenbak IDE running a program.gif|thumb|upright=1.2|A program running in a Kenbak-1 IDE/emulator]]
The '''Kenbak-1''' is considered by the [[Computer History Museum]],<ref>{{cite web|url=https://www.computerhistory.org/revolution/personal-computers/17/297 |title=What was the First PC? |accessdate=October 25, 2022}}</ref> the [[Computer Museum of America]]<ref>{{cite web|url=https://www.computermuseumofamerica.org/past-exhibits/ |title=PastExhibits - History of the PC |accessdate=October 13, 2022}}</ref> and the [[American Computer Museum]]<ref>{{cite web|url=http://www.compustory.com/Pioneers.html |title=The George R. Stibitz Computer Pioneer Award|accessdate=August 5, 2008 |url-status=dead |archiveurl=https://web.archive.org/web/20080913191154/http://www.compustory.com/Pioneers.html |archivedate=September 13, 2008 }}</ref> to be the world's first "[[personal computer]]",<ref>{{cite web |publisher=Computer History Museum |url=http://www.computerhistory.org/timeline/?year=1971 |title=Timeline of Computer History |accessdate=July 22, 2008}}</ref> invented by John Blankenbaker (born 1929) of '''Kenbak Corporation''' in 1970 and first sold in early 1971.<ref>{{Cite web|url=https://www.bbc.com/news/business-34639183|title=The man who made 'the world's first personal computer'|date=November 6, 2015|via=www.bbc.com}}</ref> Less than 50 machines were ever built, using [[Bud Industries]] enclosures as a [[Housing (engineering)|housing]].{{r|OralHist}} The system first sold for US$750.<ref>{{cite news |date=November 17, 1971 |title=Kenbak-1 The Training Computer |work=Computerworld |page=43 |url=https://books.google.com/books?id=wCl2yLDv2bAC&dq=Kenbak-1&pg=PT42 |accessdate=May 25, 2014}}</ref> Today, only 14 machines are known to exist worldwide,<ref>{{cite web|title=List of Extant Kenbak-1 Computers|url=https://www.kenbak.com/extantkenbaks|website=Kenbak.com|accessdate=13 October 2022}}</ref><ref>{{cite web|title=Kenbak-1|url=http://www.computermuseum.20m.com/kenbak.htm|website=Computer Museum of Nova Scotia|accessdate=19 November 2015}}</ref> in the hands of various collectors and museums. Production of the Kenbak-1 stopped in 1973,<ref>p. 52, "The First Personal Computer", ''Popular Mechanics'', January 2000.</ref> as Kenbak failed and was taken over by CTI Education Products, Inc. CTI rebranded the inventory and renamed it the 5050, though sales remained elusive.<ref>{{cite web|date=2005|author=Robert R Nielsen, Snr|title=Inside the Kenbak-1|website=[[YouTube]]|url=https://www.youtube.com/watch?v=lxsdL_OWumw |archive-url=https://ghostarchive.org/varchive/youtube/20211213/lxsdL_OWumw |archive-date=2021-12-13 |url-status=live|accessdate=8 November 2015}}{{cbignore}}</ref>
The '''Kenbak-1''' is considered by the [[Computer History Museum]],<ref>{{cite web|url=https://www.computerhistory.org/revolution/personal-computers/17/297 |title=What was the First PC? |accessdate=October 25, 2022}}</ref> the [[Computer Museum of America]]<ref>{{cite web|url=https://www.computermuseumofamerica.org/past-exhibits/ |title=PastExhibits - History of the PC |accessdate=October 13, 2022}}</ref> and the [[American Computer Museum]]<ref>{{cite web|url=http://www.compustory.com/Pioneers.html |title=The George R. Stibitz Computer Pioneer Award|accessdate=August 5, 2008 |url-status=dead |archiveurl=https://web.archive.org/web/20080913191154/http://www.compustory.com/Pioneers.html |archivedate=September 13, 2008 }}</ref> to be the world's first "[[personal computer]]",<ref>{{cite web |publisher=Computer History Museum |url=http://www.computerhistory.org/timeline/?year=1971 |title=Timeline of Computer History |accessdate=July 22, 2008}}</ref> invented by John Blankenbaker (born 1929) of '''Kenbak Corporation''' in 1970 and first sold in early 1971.<ref>{{Cite web|url=https://www.bbc.com/news/business-34639183|title=The man who made 'the world's first personal computer'|date=November 6, 2015|via=www.bbc.com}}</ref> Less than 50 machines were ever built, using [[Bud Industries]] enclosures as a [[Housing (engineering)|housing]].{{r|OralHist}} The system first sold for US$750.<ref>{{cite news |date=November 17, 1971 |title=Kenbak-1 The Training Computer |work=Computerworld |page=43 |url=https://books.google.com/books?id=wCl2yLDv2bAC&dq=Kenbak-1&pg=PT42 |accessdate=May 25, 2014}}</ref> Today, only 14 machines are known to exist worldwide,<ref>{{cite web|title=List of Extant Kenbak-1 Computers|url=https://www.kenbak.com/extantkenbaks|website=Kenbak.com|accessdate=13 October 2022}}</ref><ref>{{cite web|title=Kenbak-1|url=http://www.computermuseum.20m.com/kenbak.htm|website=Computer Museum of Nova Scotia|accessdate=19 November 2015}}</ref> in the hands of various collectors and museums. Production of the Kenbak-1 stopped in 1973,<ref>p. 52, "The First Personal Computer", ''Popular Mechanics'', January 2000.</ref> as Kenbak failed and was taken over by CTI Education Products, Inc. CTI rebranded the inventory and renamed it the 5050, though sales remained elusive.<ref>{{cite web|date=2005|author=Robert R Nielsen, Snr|title=Inside the Kenbak-1|website=[[YouTube]]|url=https://www.youtube.com/watch?v=lxsdL_OWumw |archive-url=https://ghostarchive.org/varchive/youtube/20211213/lxsdL_OWumw |archive-date=2021-12-13 |url-status=live|accessdate=8 November 2015}}{{cbignore}}</ref>


Revision as of 19:09, 22 November 2024

Kenbak-1
A Kenbak-1 at Deutsches Museum, Munich
DeveloperJohn Blankenbaker
ManufacturerKenbak Corporation
TypePersonal computer
Release date1971; 53 years ago (1971)
Introductory priceUS$750 (equivalent to $5,640 in 2023)
Discontinued1973 (1973)
Units sold44[1]
Memory256 bytes of memory
A program running in a Kenbak-1 IDE/emulator

The Kenbak-1 is considered by the Computer History Museum,[2] the Computer Museum of America[3] and the American Computer Museum[4] to be the world's first "personal computer",[5] invented by John Blankenbaker (born 1929) of Kenbak Corporation in 1970 and first sold in early 1971.[6] Less than 50 machines were ever built, using Bud Industries enclosures as a housing.[1] The system first sold for US$750.[7] Today, only 14 machines are known to exist worldwide,[8][9] in the hands of various collectors and museums. Production of the Kenbak-1 stopped in 1973,[10] as Kenbak failed and was taken over by CTI Education Products, Inc. CTI rebranded the inventory and renamed it the 5050, though sales remained elusive.[11]

Since the Kenbak-1 was invented before the first microprocessor, the machine did not have a one-chip CPU but was instead based purely on small-scale integration TTL chips.[12] The 8-bit machine offered 256 bytes of memory,[13] implemented on Intel's type 1404A silicon gate MOS shift registers.[14] The clock signal period was 1 microsecond (equivalent to a clock speed of 1 MHz), but the program speed averaged below 1,000 instructions per second due the many clock cycles needed for each operation and slow access to serial memory.[12]

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.[15][16]

Technical description

Registers

Kenbak-1 registers
07 06 05 04 03 02 01 00 (bit position)
Main registers
A A
B B
X X (Index)
P Program Counter
Flags
000000 C O A flags
000000 C O B flags
000000 C O X flags
Input/Output
Output Lights
Input Switches

The Kenbak-1 has a total of nine registers. All are memory mapped. It has three general-purpose registers: A, B and X. Register A is the implicit destination of some operations. Register X, also known as the index register, turns the direct and indirect modes into indexed direct and indexed indirect modes. It also has a program counter, called Register P, three "overflow and carry" registers for A, B and X, respectively, as well as an Input Register and an Output Register.[17]

Addressing modes

Add, Subtract, Load, Store, Load Complement, And, and Or instructions operate between a register and another operand using five addressing modes:

  • Immediate (operand is in second byte of instruction)
  • Memory (second byte of instruction is the address of the operand)
  • Indirect (second byte of instruction is the address of the address of the operand)
  • Indexed (second byte of instruction is added to X to form the address of the operand)
  • Indirect Indexed (second byte of instruction points to a location which is added to X to form the address of the operand)

Instruction table

The instructions are encoded in 8 bits, with a possible second byte providing an immediate value or address. Some instructions have multiple possible encodings.[17]


See also

  • Datapoint 2200, a contemporary machine with alphanumeric screen and keyboard, suitable to run non-trivial application programs
  • Mark-8, 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
  • Gigatron TTL, a 21st-century implementation of a computer using small-scale integration parts

References

  1. ^ a b "Oral History of John Blankenbaker" (PDF). Computer History Museum. June 14, 2007.
  2. ^ "What was the First PC?". Retrieved October 25, 2022.
  3. ^ "PastExhibits - History of the PC". Retrieved October 13, 2022.
  4. ^ "The George R. Stibitz Computer Pioneer Award". Archived from the original on September 13, 2008. Retrieved August 5, 2008.
  5. ^ "Timeline of Computer History". Computer History Museum. Retrieved July 22, 2008.
  6. ^ "The man who made 'the world's first personal computer'". November 6, 2015 – via www.bbc.com.
  7. ^ "Kenbak-1 The Training Computer". Computerworld. November 17, 1971. p. 43. Retrieved May 25, 2014.
  8. ^ "List of Extant Kenbak-1 Computers". Kenbak.com. Retrieved 13 October 2022.
  9. ^ "Kenbak-1". Computer Museum of Nova Scotia. Retrieved 19 November 2015.
  10. ^ p. 52, "The First Personal Computer", Popular Mechanics, January 2000.
  11. ^ Robert R Nielsen, Snr (2005). "Inside the Kenbak-1". YouTube. Archived from the original on 2021-12-13. Retrieved 8 November 2015.
  12. ^ a b Erik Klein. "Kenbak Computer Company Kenbak-1". Old-computers.com. Retrieved May 25, 2014.
  13. ^ Bill Wilson (6 November 2015). "The man who made 'the world's first personal computer'". BBC News.
  14. ^ "Technical". www.kenbak-1.net.
  15. ^ "Kenbak Theory of Operation Manual". p. 16.
  16. ^ "Official Kenbak-1 Reproduction Kit".
  17. ^ a b "Programming Reference Manual KENBAK-l Computer"
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