First Generation - 1940-1956: Vacuum Tubes
The first computers used vacuum tubes
for circuitry and magnetic drums for
memory, and were often enormous, taking up entire rooms. They were
very expensive to operate and in addition to using a great deal
of electricity, generated a lot of heat, which was often the cause
of malfunctions. First generation computers relied on machine
language to perform operations, and they could only solve
one problem at a time. Input was based on punched
cards and paper tape, and output was displayed on printouts.
The UNIVAC and ENIAC computers are examples of first-generation
computing devices. The UNIVAC was the
first commercial computer delivered to a business client, the U.S.
Census Bureau in 1951.
Second Generation - 1956-1963: Transistors
Transistors replaced vacuum tubes and
ushered in the second generation of computers. The transistor was
invented in 1947 but did not see widespread use in computers until
the late 50s. The transistor was far superior to the vacuum tube,
allowing computers to become smaller, faster, cheaper, more energy-efficient
and more reliable than their first-generation predecessors. Though
the transistor still generated a great deal of heat that subjected
the computer to damage, it was a vast improvement over the vacuum
tube. Second-generation computers still relied on punched cards
for input and printouts for output.
Second-generation computers moved from cryptic binary machine language
to symbolic, or assembly, languages,
which allowed programmers to specify instructions in words. High-level
programming languages were also being developed at this time, such
as early versions of COBOL and FORTRAN. These were also the first
computers that stored their instructions in their memory, which
moved from a magnetic drum to magnetic core
The first computers of this generation were developed for the atomic
Third Generation - 1964-1971: Integrated Circuits
The development of the integrated circuit
was the hallmark of the third generation of computers. Transistors
were miniaturized and placed on silicon
chips, called semiconductors, which
drastically increased the speed and efficiency of computers.
Instead of punched cards and printouts, users interacted with third
generation computers through keyboards and monitors and interfaced
with an operating system, which allowed the device to run many different
applications at one time with a central program that monitored the
memory. Computers for the first time became accessible to a mass
audience because they were smaller and cheaper than their predecessors.
Fourth Generation - 1971-Present: Microprocessors
The microprocessor brought the fourth
generation of computers, as thousands of integrated circuits were
built onto a single silicon chip. What in the first generation filled
an entire room could now fit in the palm of the hand. The Intel
4004 chip, developed in 1971, located all the components of the
computer - from the central processing unit and memory to input/output
controls - on a single chip.
In 1981 IBM introduced its first computer for the home user, and
in 1984 Apple introduced the Macintosh. Microprocessors also moved
out of the realm of desktop computers and into many areas of life
as more and more everyday products began to use microprocessors.
As these small computers became more powerful, they could be linked
together to form networks, which eventually led to the development
of the Internet. Fourth generation computers also saw the development
of GUIs, the mouse and handheld devices.
Fifth Generation - Present and Beyond: Artificial Intelligence
Fifth generation computing devices, based on artificial
intelligence, are still in development, though there are
some applications, such as voice recognition, that are being used
today. The use of parallel processing
and superconductors is helping to make
artificial intelligence a reality. Quantum
computation and molecular and nanotechnology
will radically change the face of computers in years to come. The
goal of fifth-generation computing is to develop devices that respond
to natural language input and are capable of learning and self-organization.