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Kenbak-1. Prototype of the first personal stored-program computer
1971. KENBAK-1. (1) Prototype Kenbak-1 computer built by its inventor, John Blankenbaker (b. 1929). Comprises motherboard with 132 integrated circuits, 2 power supplies, 2 MOS shift registers (1024 bits each) and cooling fan, in customized steel case with 3-prong power connector, the front panel with a toggle power switch, 12 incandescent lights, 15 pushbuttons and various lettering including the name "KENBAK-1." Approximately 490 x 292 x 110 mm. Preserved in a foam-padded protective instrument case. (2) Binder of documentation including Programming Reference Manual KENBAK-1 Computer (Los Angeles: KENBAK, 1971; iii, 24pp.); "Installation & maintenance" (photocopy; 8pp.); "Theory of operation" (photocopy; 9-42, 26pp.); original coding sheets, mimeographed purchase guides, reviews, stationery, etc. (3) Laboratory exercises KENBAK-1 computer. Variously paginated. Los Angeles: KENBAK, 1971. Original wrappers, spiral-bound. (4) Advertisement for the KENBAK-1 computer. In Scientific American 224, no. 3 (September 1971): 194. Whole number, in original printed wrappers. The prototype of the KENBAK-1, the world's first commercially available stored-program personal computer, so deemed in 1987 by a panel of judges, including Apple co-founder Steve Wozniak, at the Computer Museum in Boston.The stored program concept, in which both program and data are processed in an electronic memory, was the key concept in the design of the electronic computer as theorized by John von Neumann in the so-called von Neumann architecture. Because the Kenbak-1 was the first personal computer to apply this key concept in its design, it is an especially important landmark in the history of computing. Only about 40 or 50 of these machines were ever built; of which perhaps ten remain extant. The KENBAK-1, invented by computer engineer John Blankenbaker, went on sale in 1971, five years before the Apple 1. This prototype model of the KENBAK-1 is the very one used in the first demonstration of a commercial personal computer, which took place in May 1971 at an Anaheim, California convention of high school mathematics teachers. This unit was still operational in July 2015. "[The KENBAK-1] was created in 1971 by John Blankenbaker, working in his garage in Los Angeles. Initial sales commenced in September of 1971. It was intended to be educational and the professionals in the field were enthusiastic but it was a struggle to convince the non-professionals that they could buy a real computer at this price ($750), thus only some 40 devices were sold, mainly to schools. "The creator of Kenbak-1-John Blankenbaker, had a long experience in the field of computers. He started the design of a computing device as early as in the winter of 1949, when he was a 19 y.o. physics freshman at Oregon State College, inspirited by an article in a magazine. After graduation from the college in 1952, he worked at Hughes Aircraft Co. in the department for digital computers, designing the arithmetic unit for a business data processor. Some time in the late 1950s he began to think there could be simple computers which could be afforded by individuals. "As late as in the fall of 1970 he found himself unemployed and decided to investigate what might be done to make a computer for personal use. He wanted the computer to be low cost, educational, and able to give the user satisfaction with simple programs. The computer could be serial and slow which would reduce the cost yet create the environment that was desired. It should demonstrate as many programming concepts as was possible. Because of the small size, the native language of the unit would be the machine language. Above all, it had to be a stored program machine in the von Neumann sense. To keep the costs low, switches and lights were the input and output of the machine. (Some thought was given to punched card input, but it was never developed.) By the spring of 1971, the logic printed circuit board had been built and the computer was assembled. Designed before microprocessors were available, the logic consisted of small and medium scale integrated circuits, mounted on one printed circuit board. MOS shift registers implemented the serial memory. Switches in the front keyed the input and lights displayed the output. The memory was two MOS shift registers, each of 1024 bits. The computer executed several hundred instructions per second" (Dalakov). As noted above, Blankenbaker demonstrated the KENBAK-1 in May 1971 using this prototype. In September 1971 the first advertisement for the machine appeared in the Scientific American, promising potential customers that "very quickly you, or your family or students, can write programs of fun and interest." Blankenbaker intended the computer to be used for educational purposes and so did not make any special effort to market it to hobbyists, an omission he later regretted. Between 40 and 50 commercial units, differing slightly from the prototype, were manufactured and sold between 1971 and 1973, when the company folded. According to Wikipedia, about 10 KENBAK-1 units are now known to exist worldwide. Dalakov, Georgi. "The KENBAK-1 of John Blankenbaker." History of Computers, Computing and Internet. N.p., n.d. Web. Accessed 06 Nov. 2015. Wilson, Bill. "The Man Who Made 'the World's First Personal Computer.'" BBC News. N.p., 6 Nov. 2015. Web. Accessed 09 Nov. 2015.
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