First Generation of Computer: Vacuum Tubes

The first generation of computers refers to the early stages of computer development. This generation is the beginning of computer technology that gained further progress to make computers more powerful and smaller. 

First Generation of Computer

Although new innovations have added to computers and are also constantly being added, we cannot ignore the importance of the first generation. Therefore, in this article, we are going to discuss about the first generation of computers, its history, examples, advantages and disadvantages, and more. 

What You Will Learn

What is the first generation of Computer?

Although the development of computers began around 1940, the first generation of computers is considered from 1946 to 1959. During this period, computers were developed using vacuum tubes as the main component. Vacuum tubes helped provide circuitry for the central processing unit. In addition, punch-cards, paper tape, and magnetic tape were the other basic components used for input-output devices and memory needs.

Note: A vacuum tube is a device that helps amplify signals by controlling the motion of electrons in an evacuated space. It was invented by Lee de Forest.

The following image shows the structural view of Vacuum Tubes:

First Generation of Computer - Vacuum Tubes

Because vacuum tubes were much larger in size at the time, they eventually led to larger computer sizes. First-generation computers took up a lot of space in one room, even a whole room for some computers. Also, like electric bulbs, vacuum tubes used a large amount of electricity and also produced a lot of heat. The installation of vacuum tubes was so complex that they often fused. All these factors resulted in the development of the first generation computer became expensive. Therefore, first-generation computers were expensive and only large organizations were able to afford them.

In terms of software needs, first-generation computers relied on machine language, which is called the lowest-level programming language and can be easily understood by computers. Although it helped computers perform a variety of tasks, it allowed them to solve one operation at a time. First-generation computers had no multitasking support. Depending on the complexity of the operation, computers took days or even weeks to complete them.

Examples of First Generation Computers

ENIAC (Electronic Numeric Integrated and Calculator) and UNIVAC (UNIVersal Automatic Computer) are great examples of first-generation computers. The ENIAC was the first successful electronic computer, developed by J. Presper Eckert and J. W. Mauchly. On the other hand, UNIVAC was the first commercial computer invented by them. In 1951, UNIVAC was given to the US Census Bureau.

First Generation of the Computer - ENIAC

Note: The ENIAC was built using approximately 20,000 vacuum tubes, combined with about 10,000 capacitors and 70,000 resistors. A large room was needed to properly place it. The weight of this first generation computer was measured at over 30 tons.

Some other examples of the first generation computers are listed below:

Manchester Mark 1, Mark 2, Mark 3, etc.

Characteristics of First Generation Computers

Some essential characteristics or features of the first generation computers are as follows:

Use of Vacuum Tubes Technology
Based on Machine Language only
Use of Punch Cards as an Input Device
Use of Magnetic Tapes as Memory Device
Use of Paper Tape as an Output Device (output were given in printouts only)

Advantages of First Generation Computers

Some of the advantages of the first generation of computers are listed below:

The first generation computers used vacuum tubes as basic components, the only electronic component available in that period.
Vacuum tube technology made it possible for the advent of electronic computers.
The use of machine language made first-generation computers relatively faster in the beginning.
First-generation computers were faster and could complete calculations in milliseconds. 

Disadvantages of First Generation Computers

Some of the disadvantages of the first generation of computers are listed below:

First-generation computers were large in size and therefore not portable.
The storage capacity of computers was very low due to the use of magnetic tape.
First-generation computers produced too much heat, which required a large cooling system.
The functioning of input and output devices was slow.


The first generation period began in 1946 and ended in 1959. Vacuum tube technology was used in first-generation computers. First-generation computers have both advantages and disadvantages. Although these computers were huge, produced heat, required a cooling system, consumed a lot of electricity, they helped start the era of computing technology.


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