Howard Hathaway Aiken

Howard Hathaway Aiken was a pioneer in the development of automatic calculating machines. Born on March 8, 1900, in Hoboken, New Jersey, he grew up in Indianapolis, Indiana. He pursued his interest in electrical engineering by working at a utility company while in high school. Aiken then earned a B.A. degree in electrical engineering in 1923 at the University of Wisconsin. By 1935, Aiken was working on the physics of how electric charges were conducted in vacuum tubes—an important question for the new technology of electronics. This work required tedious, error-prone hand calculation. Aiken therefore began to investigate the possibility of building a large-scale, programmable, automatic computing device. As a doctoral student at Harvard, Aiken aroused considerable interest in his ideas, particularly from THOMAS J. WATSON SR., head of International Business Machines (IBM). In 1939, IBM agreed to underwrite the building of Aiken’s first calculator, the Automatic Sequence Controlled Calculator (ASCC), which became known as the Harvard Mark I.
Mechanical and electromechanical calculators were nothing new: indeed, machines from IBM, Burroughs, and others were being increasingly used in business settings. However, ordinary calculators required that operators manually set up and run each operation step by step in the complete sequence needed to solve a problem. Aiken wanted a calculator that could be programmed to carry out the sequence automatically, storing the results of each calculation for use by the next. He wanted a general-purpose programmable machine rather than an assembly of special-purpose arithmetic units. Earlier complex calculators (such as the Analytical Engine which CHARLES BABBAGE had proposed a century earlier) were very difficult to implement because of the precise tolerances needed for the intricate assembly of mechanical parts. Aiken, however, had access to a variety of tested, reliable components, including card punches, readers, and electric typewriters from IBM and the mechanical electromagnetic relays used for automatic switching in the telephone industry.
Aiken’s Mark I calculator used decimal numbers (23 digits and a sign) rather than the binary numbers of the majority of later computers. Sixty registers held whatever constant data numbers were needed to solve a particular problem. The operator turned a rotary dial to enter each digit of each constant number required for the calculation. Variable data and program instructions were entered from punched paper tape. Calculations had to be broken down into specific instruction codes similar to those in later low-level programming languages such as “store this number in this register” or “add this number to the number in that register.” The results (usually tables of mathematical function values) could be printed by an electric typewriter or output on punched cards.
The Mark I was built at IBM’s factory in Endicott, New York. It underwent its first fullscale test on Christmas Day 1943, illustrating the urgency of work under wartime conditions. The bus-sized machine (about eight feet high by 51 feet long) was then painstakingly disassembled and shipped to Harvard University, where it was up and running by March 1944. Relatively slow by comparison with the vacuum tube-based computers that would soon be designed, the Mark I was a very reliable machine. A New York Times article enthused, “At the dictation of a mathematician, it will solve in a matter of hours equations never before solved because of their intricacy and the enormous time and personnel which would be required to work them out on ordinary office calculators.”
Aiken then went to work for the U.S. Navy (and was given the rank of commander), where his team included another famous computer pioneer, the future admiral GRACE MURRAY HOPPER. The Mark I worked 24 hours a day on a variety of problems, ranging from solving equations used in lens design and radar to the ultrasecret design for the implosive core of the atomic bomb. Unlike many engineers, Aiken was comfortable managing fast-paced projects. He once quipped, “Don’t worry about people stealing an idea. If it’s original, you’ll have to ram it down their throats.” Aiken completed an improved model, the Mark II, in 1947. The Mark III of 1950 and Mark IV of 1952 were electronic rather than electromechanical, replacing relays with vacuum tubes. The Mark III used a magnetic core memory (analogous to modern RAM, or randomaccess memory) that could store and retrieve numbers relatively quickly, as well as a magnetic drum that served the function of a modern hard disk.
Compared to slightly later digital computers such as ENIAC and Univac, the sequential calculator, as its name suggests, could only perform operations in the order specified, rather than, for example, being able to loop repeatedly. (After all, the program as a whole was not stored in any sort of memory, and so previous instructions could not be reaccessed.) Yet although Aiken’s machines soon slipped out of the mainstream of computer development, they did include the modern feature of parallel processing, because different calculation units could work on different instructions at the same time. Further, Aiken recognized the value of maintaining a library of frequently needed routines that could be reused in new programs—another fundamental of modern software engineering. Aiken’s work demonstrated the value of large-scale automatic computation and the use of reliable, available technology. Computer pioneers from around the world came to Aiken’s Harvard computation lab to debate many issues that would become staples of the new discipline of computer science. By the early 1950s Aiken had retired from computer work and became a Florida business entrepreneur, enjoying the challenge of rescuing ailing businesses.
The recipient of many awards, including the Edison Medal of the Institute of Electrical and Electronics Engineers and the Franklin Institute’s John Price Award, Howard Aiken died on March 14, 1973, in St. Louis, Missouri.