Summary

A computer works with binary data in which every bit is either on or off. In order to handle complex data that can have more than two possible states, it combines several bits into larger groups of bits.

When the computer receives data from an input, it uses a set of instructions called a program to perform specific actions and return the results of those actions to an output. It uses a memory circuit as a workspace to read the program and hold the output data.

The modular operating structure of a modern personal computer extends to both hardware and software. Windows and other operating systems use a multi-level structure in which the software at each level interacts with the levels above and below it. In order to perform useful work, a personal computer uses several increasingly complex programs to start the computer and ultimately load the operating system that manages resources and supports application programs. Individual device drivers work with the operating system to take advantage of the specific features of peripheral devices, such as the keyboard, mouse and printer.

At the top of the computer's modular structure, application programs, including word processors, Web browsers, music players, games, and many other programs work with the operating system to perform the tasks that make a computer a useful tool.