Hardware Reference
In-Depth Information
work went largely uncredited because Colossus was kept secret until many years after the
war.
Besides code-breaking, systems were needed to calculate weapons trajectory and other
military functions. In 1946, John P. Eckert, John W. Mauchly, and their associates at the
Moore School of Electrical Engineering at the University of Pennsylvania built the first
large-scale electronic computer for the military. This machine became known as ENIAC,
the Electrical Numerical Integrator and Calculator. It operated on 10-digit numbers and
could multiply two such numbers at the rate of 300 products per second by finding the
value of each product from a multiplication table stored in its memory. ENIAC was about
1,000 times faster than the previous generation of electromechanical relay computers.
ENIACusedapproximately18,000vacuumtubes,occupied1,800squarefeet(167square
meters) of floor space, and consumed around 180,000 watts of electrical power. Punched
cards served as the input and output; registers served as adders and as quick-access read/
write storage.
Theexecutable instructions composing agivenprogramwerecreated viaspecified wiring
and switches that controlled the flow of computations through the machine. As such,
ENIAC had to be rewired and switched for each program to be run.
Although Eckert and Mauchly were originally given a patent for the electronic computer,
it was later voided and the patent awarded to John Atanasoff for creating the Atanasoff-
Berry Computer.
Earlier in 1945, the mathematician John von Neumann demonstrated that a computer
could have a simple, fixed physical structure and yet be capable of executing any kind
of computation effectively by means of proper programmed control without changes in
hardware.Inotherwords,youcouldchangetheprogramwithoutrewiringthesystem.The
stored-program technique
, as von Neumann's ideas are known, became fundamental for
future generations of high-speed digital computers and has become universally adopted.
The first generation of modern programmed electronic computers to take advantage of
these improvements appeared in 1947. This group of machines included EDVAC and
UNIVAC, the first commercially available computers. These computers included, for the
first time, the use of true random access memory (RAM) for storing parts of the program
and the data that is needed quickly. Typically, they were programmed directly in machine
language, although by the mid-1950s progress had been made in several aspects of ad-
vancedprogramming.ThestandoutoftheeraistheUNIVAC(UniversalAutomaticCom-
puter), which was the first true general-purpose computer designed for both alphabetical
and numerical uses. This made the UNIVAC a standard for business, not just science and
the military.
