Three computer machines have been promoted at various times as the
first electronic computers. These machines have used electronic
switches instead of electromechanical relays. Switches are a form of
vacuum tubes and they are more reliable than relays. Relay is a
mechanical device and it is like a lock on a door. However electronic
switches could 3open2 and 3close2 about 1000 times faster than
mechanical switches. A second early electronic machine
Colossus was designed by Alan Turning for the British
military in 1943. This machine played an important role in World War II
.
The first general purpose programmable electronic computer was the
Electronics Numerical Integrator and Computer (ENIAC).
It was built by J. Presper and V. John Mauchly. They began this
project in 1943 and their main focusing thing had been World War II,
but the machine was not completed until 1945. After that this machine
was used for the calculations in the construction of the hydrogen bomb.
Before ENIAC was finished, a new project began and also Presper,
Mauchly, and John von Neumann had main roles in it. This project was
called EDVAC. EDVAC was able to run faster than ENIAC and also it has
provided a large number of mathematic applications as well as use of a
memory that was large enough to hold both instructions and data.
Software technology during this period was very primitive. The first
programs were written out in machine code. By 1950 programmers used
symbolic notations , known as assembly language. This assembly language
was then converted to machine language by hand.
In this generation, computers used vacuum tubes and UNIVAC is an
example of it. Also in this generation John von Newmann developed the
idea of keeping instructions for the computer inside the computer1s
memory.
