1) When computers were first introduced in 40's and 50's programmers had to write programs to instruct CD-ROMs, laser printers and scanners.
2) The operational system controls and manages the use of the hardware and the memory.
3) There are no commands available in operating systems, they are only in word processors.
4) Microsoft developed MS-DOS to compete with IBM's PC-DOS.
5) NT requires computers with 486 CPU and 16 M random access memory.
6) OS/2 is DOS compatible because it was developed by Microsoft.
7) Traditionally, UNIX was run by many users simultaneously.
8) Windows 95 and Windows 98 are DOS compatible and have very «friendly» and convenient interface.