A History of Computers

A History of Computers

Mankind has evolved from a primitive to a highly advanced society by continually inventing tools. Stone tools, fire powder, wheels, and other inventions have changed the lives of humans dramatically. In recent history, the computer is arguably the most important invention. In today’s highly advanced society, computers affect our lives 24 hours a day: your class schedules are formulated by computers, you student record are maintained by computers, your exams are graded by computers, and numerous other functions that affect you are controlled by computers.

Although the first true computer was invented in the 1940’s, the concept of a computer is actually more than 160 years old. Charles Babbage is credited with inventing a precursor to the modern computer. In 1823 he received a grant from the British government to build a mechanical device he called the Difference Engine, intended for computing and printing mathematical tables. The device was based on rotating wheels and was operated by a single crank. Unfortunately, the technology of the time was not advanced enough to build the device. He ran into difficulties and eventually abandoned the project.

But an even more grandiose scheme was already with him. In fact, one of the reasons he gave up on the Difference Engine may have been to work on his new concept for a better machine. He called his new device the Analytical Engine. This device also was never built. His second device also was ahead of its time; the technology did not yet exist to make the device a reality. Although never built, the Analytical Engine was a remarkable achievement because its design was essentially based on the same fundamental principles of the modern computer. One principle that stands out was its programmability. With the Difference Engine, Babbage would have been able to compute only mathematical tables, but with the Analytical Engine he would have been able to compute any calculation by inputting instructions on punch cards. The method of inputting programs to computers on punch cards was actually adopted for real machines and was still in wide use as late as the 1970s.

The Analytical Engine was never built, but a demonstration program was written by Ada Lovelace, a daughter of the poet Lord Byron. The programming language Ada was named in honour of Lady Lovelace, the first computer programmer.

In the late 1930s John Atanasoff of Iowa State University, with his graduate student Clifford Berry, built the prototype of the first automatic electronic calculator. One innovation of their machine was the use of binary numbers. At around the same time, Howard Aiken of Harvard University was working on the Automatic Sequence-Controlled Calculator, known more commonly as MARK I, with support from IBM and U.S. Navy. MARK I was very similar to the Analytical Engine in design and was described as “Babbage’s dream come true:”

MARK I was an electromechanical computer based on relays. Mechanical relays were not fast enough, and MARK I was quickly replaced by machines based on electronic vacuum tubes. The first completely electronic computer, ENIAC I (Electronic Numerical Integrator and Claculator),

Was built at the University of Pennsylvania under the supervision of John W. Mauchly and J. Preper Eckert. Their work was influenced by the work of John Atanasoff.

ENIAC I was programmed laboriously by plugging wires into a control panel that resembled an old telephone switchboard. Programming took an enormous amount of the engineer’s time, and even making a simple change to a program was a time-consuming effort. While programming activities were going on, the expensive computer sat idle. To improve its productivity, John von Neumann of Princeton University proposed storing programs in the computer’s memory. This stored-program

Scheme not only improved computation speed but also allowed far more flexible ways of writing programs. For example, because a program is stored in the memory, the computer can change the program instructions to alter the sequence of the execution, thereby making it possible to get different results from a single program.

We characterized these early computers with vacuum tubes as first generation computers, Second-generation computers, with transistors replacing the vacuum tubes, started appearing in the late 1950s. Improvements in memory devices also increased processing speed further. In the early 1960s, transistors were replaced by integrated circuits and third-generation computers emerged. A single integrated circuit of this period incorporated hundreds of transistors and made the construction of minicomputers possible. Minicomputers are small enough to be placed on desktops in individual offices and labs. The early computers, on the other hand, were so huge, they easily occupied the whole basement of a large building.

Advancement of integrated circuits was phenomenal. Large-scale integrated circuits, commonly known as computer chips or silicon chips, packed the power equivalent to thousands of transistors and made the notion of a “computer on a single chip” a reality. With large-scale integrated circuits, microcomputers emerged in the mid 19702. The machines we call personal computers today are descendants of the microcomputers in the 1970s. The computer chips used in today’s personal computers pack the power equivalent to several millions of transistors. Personal computers are fourth- generation computers.

Early microcomputers were isolated, stand-alone machines. The word personal describes a machine as a personal device intended to be used by an individual. However, it did not take long to realize there was a need to share computer resources. For example, early microcomputers required a dedicated printer. Wouldn’t it make more sense to have many computers share a single printer?

Wouldn’t it also make more sense to share data among computers, instead of duplicating the same data on individual machines? Wouldn’t it be nice to send electronic messages between the computers? The notion of networked computers arose to meet those needs.

Computers of all kinds are connected into a network. A network that connects computers in a single building or in several nearby buildings is called a local area network (LAN). A network that connects geographically dispersed computers is called a wide area network (WAN). These individual networks can be connected further to form interconnected networks called internets. The most famous internet is simply called the Internet. The Internet makes the sharing of worldwide information possible and easy. The hottest tool for viewing information on the Internet is a web
browser. A web browser allows you to view multimedia information consisting of text, audio, video, and other types of information.


  1. When was the first computer invented?
  1. Why was Babbage’s Analytical Engine so remarkable?
  1. What are first-generation computers?
  1. What generation are personal computers?
  1. What do LAN and WAN stand for?