Babbage's dream come true Part I (The Harvard Mark I)
A hundred years passed before a machine like the one Babbage devised was actually built. This occurred in 1944, when the American mathematician Howard Aiken of Harvard University and a group of IBM engineers completed the Harvard Mark I computer. This calculating machine could perform any selected sequence of four arithmetical operations (addition, subtraction, multiplication, division) on numbers up to 23 digits long without human intervention.
T
he
machine was huge: it was more than 15 meters long
and
2.4 m high, it weighed 35 tons, contained about 800 km of wire and
about 750,000 separate parts. (See
Figure 1) Its
78 adding machines and calculators were controlled by mechanical and
electrical devices.
Figure 1
The Harvard Mark I, 1943
It should be said that Aiken mistrusted the concept of storing program within a computer. The Mark I was programmed to solve problems by means of a paper tape on which coded instructions were punched. Once so programmed, the calculator could be easily operated by persons with little training. For input and output, it used three paper tape readers, two card readers, a cardpunch, and two typewriters. The Mark I was used for military purposes, including the development of the atomic bomb.
Aiken was not familiar with the Analytical Engine when he designed the Mark I. Later, after people had pointed out Babbage's work to him, he was amazed to learn how many of his ideas Babbage had anticipated.
The main difference between the Analytical Engine and The Mark I is that the latter1 was operated by electricity instead of steam. Electricity was also used to transmit information from one part of the machine to another, replacing the complex mechanical parts by relays and electromagnetic components.
But, along with2 several other electromechanical computers built at about the same time, the Mark I was scarcely completed before it was obsolete. The electromechanical machines simply were not fast enough. Their speed was seriously limited by the time required for mechanical parts to move from one position to another. For example, the Mark I took six seconds for a multiplication and twelve for a division; this was only five or six times faster than what a human with an old desk calculator could do.
Continuing his work, Aiken completed the improved versions of the Mark I (Mark II, III and IV). He also wrote numerous articles on electronics, switching theory3, and data processing as well as developed the first computer science program4 at Harvard University. On the other hand, Aiken advised the National Bureau of Standards5 not to support the development of computers. He was sure that there would never be a need for more than five or six computers nationwide.
Notes: 1 the latter – последний (из двух названных, из упомянутых);
2along with – наряду с;
3switching theory – теория переключательных (релейных) схем;
4computer science program – программа по теории вычислительных машин и систем;
5the National Bureau of Standards – Национальный институт стандартов и технологий (U.S.).