In the 1970’s , CP/M (Control Monitor Program) was the widely used operating system, it was designed for 8-bit processor such as the Z80 and 8085 and 8080A.
In the 1980’s when the 8-bit microprocessor were replaced by
16-bit processor in the personal computers (PCs), MS-DOS (Microsoft Disk
Operating System) replace CP/M. MS-DOS (also known as DOD or PC-DOS) was
designed to handle 16 bit processor system.
MS-DOS at that time was text-based operating system mean that
command are written using keyboard to perform any task and operation. It was
very very hard to operate because every operation and task need a specific
command, which is very hard to learn a large numbers of commands.
So time latter in 1990’s Microsoft launch a graphical uses
interface (GUI) operating system such as Window 3.1and 95. this type of window
was enable the user to write commands by clicking on the icons rather then
using then a keyboard. Mean in the icons commands are written earlier as click
that command run and operation will be start to perform.
After then 32 and then 64-bit processor were launched then
operating system such as UNIX, Linux, OS/2, Window 95/98/2000, ME (Millennium)
and NT were launched.
Now a days Window XP/7 were launched with advance technology and
feature. In the last of 2012 Window 8 were launched with new features an high
speed then others windows.