Second Generation of Computer: Transistors

The development of computers began in the first generation, but there were some problems such as size, speed, reliability, and more. All these problems drove development forward and aimed to minimize such issues to the maximum extent. This eventually introduced the second generation of computer.

Second Generation of Computer

In this article, we are going to discuss about the second generation of computers, its history, examples, advantages and disadvantages, and more.

What You Will Learn

What is the second generation of Computer?

Second-generation computers were developed using transistors as the basic component instead of vacuum tubes used in the first generation. The transistors were much better than vacuum tubes because the transistors were of relatively small size, fast in speed, and cheap in cost. In addition, the transistor consumed less energy and allowed the computer to be more reliable.

Although the transistor was invented in 1947, it was not in use in computers. Transistors were used in many electronic devices in the late 1950s. Later, it was also incorporated into computers in place of vacuum tubes. Because the first transistor-based computer, called the TX-0, was introduced in 1956, some sources say the second generation started in 1956. However, from 1959 to 1965, transistors were widely used in computers. Therefore, the period of the second generation of computers is considered from 1959 to 1965.

Note: A transistor refers to a semiconductor device that helps amplify or switch electronic signals and electrical power. It was invented at Bell Labs jointly by three individuals, William Shockley, Walter Houser Brattain, and John Bardeen in 1947. 

The following image shows the structural view of transistors:

Second Generation of Computer - Transistors

Unlike the first generation computers, the computers in the second generation used assembly language instead of binary machine language. This allowed developers to input instructions in words. Also, high-level languages like COBOL and FORTRAN were introduced as the early versions which were also used in the second generation computers. The second-generation computers typically used batch processing combined with the multiprogramming operating system.

In addition, computers used magnetic cores as primary memory and magnetic tapes and disks as other storage devices. These computers were referred to as the first type of computers that could store instructions in their memory due to the use of magnetic core technology.

Examples of Second Generation Computers

Second-generation computers used arithmetic circuits and sets of index resistors, making these computers relatively different from computers developed in the first generation using vacuum tubes. Due to such circuits in the second generation, computers had an isolate input and output operations that eventually helped to manage both fixed-point and floating-point operations efficiently.

Second-generation computers were widely used for commercial purposes, especially for businesses and scientific jobs. UNIVAC 1108, CDC 3600, IBM 7070, and IBM 7094 are great examples of second-generation computers. 

Second Generation of the Computer - IBM Series

The second-generation series of computers from IBM saw approximately six times higher computational speed than computers developed using vacuum tubes in the first generation. In particular, the IBM 7090 was built using over 50,000 transistors, and extremely fast magnetic cores. It is believed that when the eight data channels were used jointly, the IBM 7090 was capable of performing approximately 3,000,000 bits of R / W operations per second. More practically, it can process about 229,000 additions or subtractions or 39,500 multiplications, or 32,700 divisions in a second.

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

CDC 1604
CDC 3600
IBM 1400 series
IBM 1600 series
IBM 7000 series
Honeywell 400, etc.

Characteristics of Second Generation Computers

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

Use of transistors as basic technology
Based on assembly language and high-level programming languages
Telephone line access for communication
Use of magnetic cores as primary memory, and magnetic tapes and magnetic disks as secondary storage devices
Use of Paper Tape as an Output Device (output were given in printouts only)

Advantages of Second Generation Computers

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

Due to the use of transistors, second-generation computers were comparatively small and portable.
Second-generation computers used less energy and generated less amount of heat than first-generation computers.
Computers were relatively cheaper in the second generation than the first generation of computers.
The problem of hardware failure was somewhat reduced compared to first-generation computers.
Second-generation computers were more reliable and faster. They could calculate data in microseconds.

Disadvantages of Second Generation Computers

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

Even after the second generation computers generated comparatively low heat than the first generation computers, the cooling system was still required.
Second-generation computers required continuous maintenance for proper functioning.
Punch cards were still used as input devices in second generation computers, slowing down the input process like the first generation computers.
Although second-generation computers were somewhat cheaper than first-generation computers, they were still expensive.
Second-generation computers were used for specific requirements and their commercial production was also difficult.


The second-generation period began in 1959 and ended in 1965. The second-generation computers used transistors as the core component. Although the idea was to add more advantages to second-generation computers than first-generation computers, second-generation computers still had some disadvantages. This eventually led to the development of computers in the next generation, called the third generation of computers.

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