Alverno College
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What is System Software?

The operating system and utility programs are the two major categories of system software. Just as the processor is the nucleus of the computer system, the operating system is the nucleus of all software activity.

The operating system is the most important program that runs on a computer. Every general-purpose computer must have an operating system to run other programs. Operating systems perform basic tasks, such as

  • recognizing input from the keyboard
  • sending output to the display screen
  • keeping track of files and directories on the disk
  • controlling peripheral devices such as disk drives and printers.

It is the first program loaded into memory when the computer is turned on and, in a sense, brings life to the computer hardware. Without it, you cannot use your word processing software, spreadsheet software, or any other applications.


Without an operating system, you cannot communicate with your computer. When you give the computer a command, the operating system relays the instructions to the 'brain' of the computer, called the microprocessor or CPU. You cannot speak directly to the CPU because it only understands machine language. When you are working in an application software program, such as Microsoft Word, commands that you give the application are sent through the operating system to the CPU. Windows2000, Window95/98, Mac OS, Unix and DOS are all examples of operating systems.

Operating system graphic



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What are Utility Programs?

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Last Updated 7/23/03