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2.1 / A BRIEF HISTORY OF COMPUTERS 25

In 1947, Eckert and Mauchly formed the Eckert-Mauchly Computer Corpora-
tion to manufacture computers commercially.Their first successful machine was the
UNIVAC I (Universal Automatic Computer), which was commissioned by the
Bureau of the Census for the 1950 calculations.The Eckert-Mauchly Computer Cor-
poration became part of the UNIVAC division of Sperry-Rand Corporation, which
went on to build a series of successor machines.
The UNIVAC I was the first successful commercial computer. It was intended
for both scientific and commercial applications. The first paper describing the sys-
tem listed matrix algebraic computations, statistical problems, premium billings
for a life insurance company, and logistical problems as a sample of the tasks it could
perform.
The UNIVAC II, which had greater memory capacity and higher performance
than the UNIVAC I, was delivered in the late 1950s and illustrates several trends that
have remained characteristic of the computer industry. First, advances in technology
allow companies to continue to build larger, more powerful computers. Second, each
3
company tries to make its new machines backward compatible with the older ma-
chines.This means that the programs written for the older machines can be executed
on the new machine. This strategy is adopted in the hopes of retaining the customer
base; that is, when a customer decides to buy a newer machine, he or she is likely to
get it from the same company to avoid losing the investment in programs.
The UNIVAC division also began development of the 1100 series of comput-
ers, which was to be its major source of revenue. This series illustrates a distinction
that existed at one time. The first model, the UNIVAC 1103, and its successors for
many years were primarily intended for scientific applications, involving long and
complex calculations. Other companies concentrated on business applications, which
involved processing large amounts of text data. This split has largely disappeared,
but it was evident for a number of years.
IBM, then the major manufacturer of punched-card processing equipment, de-
livered its first electronic stored-program computer, the 701, in 1953.The 701 was in-
tended primarily for scientific applications [BASH81]. In 1955, IBM introduced the
companion 702 product, which had a number of hardware features that suited it to
business applications. These were the first of a long series of 700/7000 computers
that established IBM as the overwhelmingly dominant computer manufacturer.

The Second Generation:Transistors
The first major change in the electronic computer came with the replacement of the
vacuum tube by the transistor. The transistor is smaller, cheaper, and dissipates less
heat than a vacuum tube but can be used in the same way as a vacuum tube to con-
struct computers. Unlike the vacuum tube, which requires wires, metal plates, a glass
capsule, and a vacuum, the transistor is a solid-state device, made from silicon.
The transistor was invented at Bell Labs in 1947 and by the 1950s had launched
an electronic revolution. It was not until the late 1950s, however, that fully transis-
torized computers were commercially available. IBM again was not the first

3 Also called downward compatible. The same concept, from the point of view of the older system, is
referred to as upward compatible, or forward compatible.