Prior to the 1950's, computers such as the ENIAC, or Electronic Numerical Integrator and Computer, had no operating system as such. In order to run a program on the ENIAC, many people were required in order to manually connect wires and set switches so the program would run properly. It might take a week or longer to perform all these operations for a program that took a few minutes or hours to run.
In 1981 IBM began selling its personal computer, the PC and MS-DOS (Microsoft Disk Operating System) was chosen as the standard for this computer. Before this, each type, or brand of computer had its own particular operating system. Since programs are specific to an operating system, software that would work on one computer would not work on another. With the development of MS-DOS, there was at least a standard operating system for the so-called PC compatible systems. Most machines based on the Intel chips used DOS as the standard operating system, although computers based on different CPUs (like the Apple lines) used their own unique operating system.
Why was that a problem for computer users?
In 1983 Apple introduced the first publicly available microcomputer with a graphical user interface, the Apple Lisa. The reason most people have not heard about the Apple Lisa is because it did not sell well due to its prohibitive selling price of 2,500. The high sales of this computer showed the industry that people really wanted to have computers, but they wanted them to be easier to use, and wanted GUIs. The DOS world stayed away from the GUI approach until the advent of Windows.
UNIX , another popular operating system, was created in 1969 at Bell Laboratories, which was the research facility of AT&T. It was born of a need for a less expensive and more friendly programming environment. It retains its aura of higher - end computing.