Operating Systems. When a brand new computer comes off the factory assembly line, it can do nothing

When a brand new computer comes off the factory assembly line, it can do nothing. The hardware needs software to make it work. Are we talking about applications software such as word processing or spreadsheet software? Partly. But an applications software package does not communicate directly with the hardware. Between the applications software and the hardware is a software interface - an operating system. An operating system is a set of programs that lies between applications software and the computer hardware.

The most important program in the operating system, the program that manages the operating system, is the supervisor program, most of which remains in memory and is thus referred to as resident. The supervisor controls the entire operating system and loads into memory other operating system programs (called nonresident) from disk storage only as needed.

An operating system has three main functions: (1) manage the computer's resources, such as the central processing unit, memory, disk drives, and printers, (2) establish a user interface, and (3) execute and provide services for applications software. Keep in mind, however, that much of the work of an operating system is hidden from the user. In particular, the first listed function, managing the computer's resources, is taken care of without the user being aware of the details. Furthermore, all input and output operations, although invoked by an applications program, are actually carried out by the operating system.

5. Complete the gaps in this summary of the text on operating systems using these linking words and phrases:

Although in addition because

such as but therefore

The user is aware of the effects of different applications programs _______________ operating systems are invisible to most users. They lie between applications programs, _______________wordprocessing, and the hardware. The supervisor program is the most important. It remains in memory, _______________it is referred to as resident. Others are called non-resident _______________they are loaded into memory only when needed. Operating systems manage the computer's resources, _______________the central processing unit _______________, they establish a user interface, and execute and provide services for applications software _______________input and output operations are invoked by applications programs, they are carried out by the operating system.