Operating System Series
Part 1: Introduction to Operating System & Generations


IBM invented the first operating system sold along with a computer in 1964 to operate its mainframe computer. It’s called the IBM Systems/360.

FIRST GENERATION : 1945 – 1955
  • Computers based on Vacuum Tube technology.
  • No standard operating system software.
  • Typical program included every instruction needed by the computer to perform the task requested .
  • Poor machine utilization.
  • CPU processed data and performed calculations for a fraction of available time. Early programs designed to use the resources conservatively .
  • In the second generation, computer uses discrete transistors instead of vacuum tubes.
  • Transistors led to the development of the computer systems.
  • These machines were named as Mainframe.
  • They were locked in air-conditioned computer rooms with staff to operate them.


  • Large Scale Integrated Circuits were introduced.
  • IC’s combined electronic components into a small silicon disc, made from quartz.
  • Higher packing density, i.e. number of components fabricated in an IC.
  • Operating system allowed the machines to run many applications.
  • The microprocessor brought the fourth generation of computers, at thousands of integrated circuits were built into a single silicon chip.
  • The intel 4004 chip, located all the components of the computer – from the central processing unit and memory to input/output controls – on a single chip.
  • As the small computers became more powerful, they could be linked to form a network which eventually led to the development of the internet.
  • Fourth generation computers also saw the development of GUI’s, the mouse devices.


Operating system also differs by permissions in shell and kernel. Operating system permits users to run programs by granting access and permissions.


An operating system software that manages computer hardware, software resources and provides common services for computer programs.

What Does an Operating System Do?

We know that without an operating system, a computer is useless. At least one operating system is necessary to run other programs and an application like Chrome, MS Word, games, etc.

Computer = Hardware + Operating System + Application Software + Users

HARDWARE: Hardware comprises CPU, memory and input/output devices which contributes for computing a task.

APPLICATION SOFTWARE: These consists of word processors, spreadsheets, web browsers which defines the way these resources are used to solve users computing problems.


Case 1: Most of the users sit in front of PC, such system is designed for one user to monopolize its users.

Case 2: Users sit at a terminal connected to a mainframe or minicomputer. Other users are accessing the same computer through other terminals . These users share resources and may exchange information.

Case 3: Users at workstations connected to a network of other workstations and servers. These users have dedicated resources at their disposal, but they also share resources such as networking and servers – file, compute and print servers. Therefore, their operating system compromises between individual usability and resource utilization.

Case 4: Some computers have little or no user view. For example, embedded computers in home devices and automobiles may have numeric keypads and may turn indicator lights on or off to show status, but they and their operating systems are designed primarily to run without user intervention.


In this article I have summarized the introduction to operating system, history of operating system and what an operating system does. My next article will come up with few more concepts of operating system.

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