Saturday, June 12, 2010

The First Generation: Vacuum Tube Computers (1945–1953)

Although Babbage is often called the “father of computing,” his machines were

mechanical, not electrical or electronic. In the 1930s, Konrad Zuse (1910–1995)

picked up where Babbage left off, adding electrical technology and other improvements

to Babbage’s design. Zuse’s computer, the Z1, used electromechanical

relays instead of Babbage’s hand-cranked gears. The Z1 was programmable and

cally to solve systems of linear equations, we cannot call it a general-purpose

computer. There were, however, some features that the ABC had in common with

the general-purpose ENIAC (Electronic Numerical Integrator and Computer),

which was invented a few years later. These common features caused considerable

controversy as to who should be given the credit (and patent rights) for the

invention of the electronic digital computer. (The interested reader can find more

details on a rather lengthy lawsuit involving Atanasoff and the ABC in Mollenhoff


John Mauchly (1907–1980) and J. Presper Eckert (1929–1995) were the two

principle inventors of the ENIAC, introduced to the public in 1946. The ENIAC

is recognized as the first all-electronic, general-purpose digital computer. This

machine used 17,468 vacuum tubes, occupied 1,800 square feet of floor space,

weighed 30 tons, and consumed 174 kilowatts of power. The ENIAC had a memory

capacity of about 1,000 information bits (about 20 10-digit decimal numbers)

and used punched cards to store data.

John Mauchly’s vision for an electronic calculating machine was born from

his lifelong interest in predicting the weather mathematically. While a professor

of physics at Ursinus College near Philadelphia, Mauchly engaged dozens of

adding machines and student operators to crunch mounds of data that he believed

would reveal mathematical relationships behind weather patterns. He felt that if

he could have only a little more computational power, he could reach the goal

that seemed just beyond his grasp. Pursuant to the Allied war effort, and with

ulterior motives to learn about electronic computation, Mauchly volunteered for a

crash course in electrical engineering at the University of Pennsylvania’s Moore

School of Engineering. Upon completion of this program, Mauchly accepted a

teaching position at the Moore School, where he taught a brilliant young student,

J. Presper Eckert. Mauchly and Eckert found a mutual interest in building an

electronic calculating device. In order to secure the funding they needed to build

their machine, they wrote a formal proposal for review by the school. They portrayed

their machine as conservatively as they could, billing it as an “automatic

calculator.” Although they probably knew that computers would be able to function

most efficiently using the binary numbering system, Mauchly and Eckert

designed their system to use base 10 numbers, in keeping with the appearance of

building a huge electronic adding machine. The university rejected Mauchly and

Eckert’s proposal. Fortunately, the United States Army was more interested.

had a memory, an arithmetic unit, and a control unit. Because money and resources

were scarce in wartime Germany, Zuse used discarded movie film instead of

punched cards for input. Although his machine was designed to use vacuum tubes,

Zuse, who was building his machine on his own, could not afford the tubes. Thus,

the Z1 correctly belongs in the first generation, although it had no tubes.

Zuse built the Z1 in his parents’ Berlin living room while Germany was at

war with most of Europe. Fortunately, he couldn’t convince the Nazis to buy his

machine. They did not realize the tactical advantage such a device would give

them. Allied bombs destroyed all three of Zuse’s first systems, the Z1, Z2, and

Z3. Zuse’s impressive machines could not be refined until after the war and ended

up being another “evolutionary dead end” in the history of computers.

Digital computers, as we know them today, are the outcome of work done by

a number of people in the 1930s and 1940s. Pascal’s basic mechanical calculator

was designed and modified simultaneously by many people; the same can be said

of the modern electronic computer. Notwithstanding the continual arguments

about who was first with what, three people clearly stand out as the inventors of

modern computers: John Atanasoff, John Mauchly, and J. Presper Eckert.

John Atanasoff (1904–1995) has been credited with the construction of the

first completely electronic computer. The Atanasoff Berry Computer (ABC) was

a binary machine built from vacuum tubes. Because this system was built specifi

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