- An OS is software that manages the computer hardware.
- Mainframe OSs are designed primarily to optimize utilization of hardware.
- Personal computer (PC) OSs support complex games, business applications, and everything in between.
- OSs for handheld computers are designed to provide an environment in which a user can easily interface with the computer to execute programs.
- Thus, some OSs are designed to be convenient, others to be efficient, and others some combination of the two.
Abstract view. Where the OS fits in.
- A computer system can be divided roughly into four components: the hardware, the OS, the application programs, and the users (see Fig. 2.1).
- Electronic, mechanical, optical devices.
- The central processing unit (CPU), the memory, and the input/output (I/O) devices-provides the basic computing resources for the system.
- The hardware must provide appropriate mechanisms to ensure the correct operation of the computer system and to prevent user programs from interfering with the proper operation of the system.
- Programs. Without support software, a computer is of little use. With its software, however, a computer can store, manipulate, and retrieve information.
- Software can be grouped into the following categories:
- systems software (OS & utilities)
- applications software (user programs; word processors, spreadsheets, compilers, database systems, games, web browsers etc.)
- As a summary;
- Hardware provides basic computing resources (CPU, memory, I/O devices).
- OS controls and coordinates the use of the hardware among the various application programs for the various users.
- Provides orderly and controlled allocation (i.e., sharing, optimization of resource utilization) and use of the resources by the users (jobs) that compete for them.
- An OS is similar to a government. Like a government, it performs no useful function by itself. It simply provides an environment within which other programs can do useful work.