1940 to 1949: Computing During World War II and the Postwar Era - The Technical and Social History of Software Engineering - page 77

Table 3.1 Computers Developed from 1940 to 1950
The earlier computers were electromechanical, while the later computers were
electronic. None of them used transistors or integrated circuits, because neither
of these inventions would be patented until later in the 1950s. Tubes and relays
provided the computing power. Mercury delay lines and cathode ray tubes
provided the storage. The magnetic core arrived for the Whirlwind in 1951, so it
is not shown in Table 3.1 .
These early computers were not commercial products but were custom built by
hand and required thousands of vacuum tubes and relays and millions of hand-
soldered joints. Early computer construction was highly labor intensive in the era
before printed circuits and automated assembly lines.
As can be seen from Table 3.1 , computer research during the war years and the
postwar era was a truly international undertaking, with the United States and the