The first true digital electronic computer was created by John V Atanasoff during 1937-
1942. The Atanasoff-Berry Computer (called ABC figure 2.8) was the first to use moderndigital switching techniques. Vacuum tubes were used as switches (the needs of switches
are explained later). The concepts of using binary arithmetic and logic circuits were
introduced to computing world by this ABC.
The first large-scale electronic computer for the military which was named as ENIAC
(Electrical Numerical Integrator and Calculator figure 2.9) was invented in 1946 by John
Presper Eckert and John William Mauchly. This was a valve based computer and now
referred to as a first generation computer. ENIAC had the following characteristics:
• Operated on 10-digit numbers and could multiply two such numbers at the rate of
300 products per second.
• Was about 1000 times faster than the previous generation of electromechanical
relay computers.
• Was a valve based computer.
• Used approximately 18,000 vacuum tubes, and occupied 1,800 square feet of floor
space and consumed around 180,000 watts of electrical power.
• Punch cards were used as input and output and registers served as adders and also
as quick-access read/write storage.
• The executable instructions of a program were created using specified 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.
To be continued...
