Notes

1. ^ In 1946, ENIAC required an estimated 174 kW. By comparison, a modern laptop computer may use around 30 W; nearly six thousand times less. "Approximate Desktop & Notebook Power Usage". University of Pennsylvania. http://www.blogger.com/goog_325049690. Retrieved 2009-06-20. 
2. ^ Early computers such as Colossus and ENIAC were able to process between 5 and 100 operations per second. A modern "commodity" microprocessor (as of 2007) can process billions of operations per second, and many of these operations are more complicated and useful than early computer operations. "Intel Core2 Duo Mobile Processor: Features". Intel Corporation. http://www.blogger.com/goog_325049690. Retrieved 2009-06-20. 
3. ^ computer, n.. Oxford English Dictionary (2 ed.). Oxford University Press. 1989. http://www.blogger.com/goog_325049690. Retrieved 2009-04-10. 
4. ^ * Ifrah, Georges (2001). The Universal History of Computing: From the Abacus to the Quantum Computer. New York: John Wiley & Sons. ISBN 0471396710.  From 2700 to 2300 BC, Georges Ifrah, pp.11
5. ^ Berkeley, Edmund (1949). Giant Brains, or Machines That Think. John Wiley & Sons. p. 19.  Edmund Berkeley
6. ^ According to advertising on Pickett's N600 slide rule boxes."Pickett Apollo Box Scans". Copland.udel.edu. http://www.blogger.com/goog_325049690. Retrieved 2010-02-20. 
7. ^ "Discovering How Greeks Computed in 100 B.C.". The New York Times. 31 July 2008. http://www.blogger.com/goog_325049690. Retrieved 27 March 2010. 
8. ^ "Heron of Alexandria". http://www.blogger.com/goog_325049690. Retrieved 2008-01-15. 
9. ^ Felt, Dorr E. (1916). Mechanical arithmetic, or The history of the counting machine. Chicago: Washington Institute. p. 8. http://www.blogger.com/goog_325049690.  Dorr E. Felt
10. ^ "Speaking machines". The parlour review, Philadelphia 1 (3). January 20, 1838. http://www.blogger.com/goog_325049690. Retrieved October 11, 2010. 
11. ^ Felt, Dorr E. (1916). Mechanical arithmetic, or The history of the counting machine. Chicago: Washington Institute. p. 10. http://www.blogger.com/goog_325049690.  Dorr E. Felt
12. ^ "Pascal and Leibnitz, in the seventeenth century, and Diderot at a later period, endeavored to construct a machine which might serve as a substitute for human intelligence in the combination of figures" The Gentleman's magazine, Volume 202, p.100
13. ^ Babbage's Difference engine in 1823 and his Analytical engine in the mid-1830s
14. ^ "It is reasonable to inquire, therefore, whether it is possible to devise a machine which will do for mathematical computation what the automatic lathe has done for engineering. The first suggestion that such a machine could be made came more than a hundred years ago from the mathematician Charles Babbage. Babbage's ideas have only been properly appreciated in the last ten years, but we now realize that he understood clearly all the fundamental principles which are embodied in modern digital computers" Faster than thought, edited by B. V. Bowden, 1953, Pitman publishing corporation
15. ^ "...Among this extraordinary galaxy of talent Charles Babbage appears to be one of the most remarkable of all. Most of his life he spent in an entirely unsuccessful attempt to make a machine which was regarded by his contemporaries as utterly preposterous, and his efforts were regarded as futile, time-consuming and absurd. In the last decade or so we have learnt how his ideas can be embodied in a modern digital computer. He understood more about the logic of these machines than anyone else in the world had learned until after the end of the last war" Foreword, Irascible Genius, Charles Babbage, inventor by Maboth Moseley, 1964, London, Hutchinson
16. ^ In the proposal that Aiken gave IBM in 1937 while requesting funding for the Harvard Mark I we can read: "Few calculating machines have been designed strictly for application to scientific investigations, the notable exceptions being those of Charles Babbage and others who followed him ... After abandoning the difference engine, Babbage devoted his energy to the design and construction of an analytical engine of far higher powers than the difference engine ... Since the time of Babbage, the development of calculating machinery has continued at an increasing rate." Howard Aiken, Proposed automatic calculating machine, reprinted in: The origins of Digital computers, Selected Papers, Edited by Brian Randell, 1973, ISBN 3-540-06169-X
17. ^ "Intel Museum - The 4004, Big deal then, Big deal now". Intel.com. http://www.blogger.com/goog_325049690. Retrieved 2012-01-29. 
18. ^ From cave paintings to the internet HistoryofScience.com
19. ^ See: Anthony Hyman, ed., Science and Reform: Selected Works of Charles Babbage (Cambridge, England: Cambridge University Press, 1989), page 298. It is in the collection of the Science Museum in London, England. (Delve (2007), page 99.)
20. ^ The analytical engine should not be confused with Babbage's difference engine which was a non-programmable mechanical calculator.
21. ^ "Columbia University Computing History: Herman Hollerith". Columbia.edu. http://www.blogger.com/goog_325049690. Retrieved 2010-12-11. 
22. ^ ^{a b} "Alan Turing – Time 100 People of the Century". Time Magazine. http://www.blogger.com/goog_325049690. Retrieved 2009-06-13. "The fact remains that everyone who taps at a keyboard, opening a spreadsheet or a word-processing program, is working on an incarnation of a Turing machine" 
23. ^ "John Vincent Atanasoff and the Birth of Electronic Digital Computing". Cs.iastate.edu. http://www.blogger.com/goog_325049690. Retrieved 2012-01-29. 
24. ^ "John Vincent Atanasoff - the father of the computer". Columbia.edu. http://www.blogger.com/goog_325049690. Retrieved 2012-01-29. 
25. ^ "Atanasoff-Berry Computer". http://www.blogger.com/goog_325049690. Retrieved 2010-11-20. 
26. ^ "Spiegel: The inventor of the computer's biography was published". Spiegel.de. 2009-09-28. http://www.blogger.com/goog_325049690. Retrieved 2010-12-11. 
27. ^ "Inventor Profile: George R. Stibitz". National Inventors Hall of Fame Foundation, Inc.. http://www.blogger.com/goog_325049690. 
28. ^ Rojas, R. (1998). "How to make Zuse's Z3 a universal computer". IEEE Annals of the History of Computing 20 (3): 51–54. doi:10.1109/85.707574. 
29. ^ B. Jack Copeland, ed., Colossus: The Secrets of Bletchley Park's Codebreaking Computers, Oxford University Press, 2006
30. ^ "Robot Mathematician Knows All The Answers", October 1944, Popular Science. Books.google.com. http://www.blogger.com/goog_325049690. Retrieved 2010-12-11. 
31. ^ Lavington 1998, p. 37
32. ^ This program was written similarly to those for the PDP-11 minicomputer and shows some typical things a computer can do. All the text after the semicolons are comments for the benefit of human readers. These have no significance to the computer and are ignored. (Digital Equipment Corporation 1972)
33. ^ It is not universally true that bugs are solely due to programmer oversight. Computer hardware may fail or may itself have a fundamental problem that produces unexpected results in certain situations. For instance, the Pentium FDIV bug caused some Intel microprocessors in the early 1990s to produce inaccurate results for certain floating point division operations. This was caused by a flaw in the microprocessor design and resulted in a partial recall of the affected devices.
34. ^ Taylor, Alexander L., III (1984-04-16). "The Wizard Inside the Machine". TIME. http://www.blogger.com/goog_325049690. Retrieved 2007-02-17. 
35. ^ Even some later computers were commonly programmed directly in machine code. Some minicomputers like the DEC PDP-8 could be programmed directly from a panel of switches. However, this method was usually used only as part of the booting process. Most modern computers boot entirely automatically by reading a boot program from some non-volatile memory.
36. ^ However, there is sometimes some form of machine language compatibility between different computers. An x86-64 compatible microprocessor like the AMD Athlon 64 is able to run most of the same programs that an Intel Core 2 microprocessor can, as well as programs designed for earlier microprocessors like the Intel Pentiums and Intel 80486. This contrasts with very early commercial computers, which were often one-of-a-kind and totally incompatible with other computers.
37. ^ High level languages are also often interpreted rather than compiled. Interpreted languages are translated into machine code on the fly, while running, by another program called an interpreter.
38. ^ The control unit's role in interpreting instructions has varied somewhat in the past. Although the control unit is solely responsible for instruction interpretation in most modern computers, this is not always the case. Many computers include some instructions that may only be partially interpreted by the control system and partially interpreted by another device. This is especially the case with specialized computing hardware that may be partially self-contained. For example, EDVAC, one of the earliest stored-program computers, used a central control unit that only interpreted four instructions. All of the arithmetic-related instructions were passed on to its arithmetic unit and further decoded there.
39. ^ Instructions often occupy more than one memory address, therefore the program counter usually increases by the number of memory locations required to store one instruction.
40. ^ David J. Eck (2000). The Most Complex Machine: A Survey of Computers and Computing. A K Peters, Ltd.. p. 54. ISBN 9781568811284. 
41. ^ Erricos John Kontoghiorghes (2006). Handbook of Parallel Computing and Statistics. CRC Press. p. 45. ISBN 9780824740672. 
42. ^ Flash memory also may only be rewritten a limited number of times before wearing out, making it less useful for heavy random access usage. (Verma & Mielke 1988)
43. ^ Donald Eadie (1968). Introduction to the Basic Computer. Prentice-Hall. p. 12. 
44. ^ Arpad Barna; Dan I. Porat (1976). Introduction to Microcomputers and the Microprocessors. Wiley. p. 85. ISBN 9780471050513. 
45. ^ Jerry Peek; Grace Todino, John Strang (2002). Learning the UNIX Operating System: A Concise Guide for the New User. O'Reilly. p. 130. ISBN 9780596002619. 
46. ^ Gillian M. Davis (2002). Noise Reduction in Speech Applications. CRC Press. p. 111. ISBN 9780849309496. 
47. ^ However, it is also very common to construct supercomputers out of many pieces of cheap commodity hardware; usually individual computers connected by networks. These so-called computer clusters can often provide supercomputer performance at a much lower cost than customized designs. While custom architectures are still used for most of the most powerful supercomputers, there has been a proliferation of cluster computers in recent years. (TOP500 2006)
48. ^ Agatha C. Hughes (2000). Systems, Experts, and Computers. MIT Press. p. 161. ISBN 9780262082853. "The experience of SAGE helped make possible the first truly large-scale commercial real-time network: the SABRE computerized airline reservations system..." 
49. ^ "A Brief History of the Internet". Internet Society. http://www.blogger.com/goog_325049690. Retrieved 2008-09-20. 
50. ^ "Computer architecture: fundamentals and principles of computer design" by Joseph D. Dumas 2006. page 340.
51. ^ "Definition of computer". Thefreedictionary.com. http://www.blogger.com/goog_325049690. Retrieved 2012-01-29. 
52. ^ Most major 64-bit instruction set architectures are extensions of earlier designs. All of the architectures listed in this table, except for Alpha, existed in 32-bit forms before their 64-bit incarnations were introduced.