Hardware

At the heart of the modern computer is the microprocessor. A microprocessor is built onto a single tiny piece of silicon and fitted into a plastic package as small as two square centimeters. Typically, this package has many electrical connections that accept inputs and provide outputs for other electrical components and communicate with the microprocessor's internal circuitry. In computer language, this package is referred to as a computer chip. The most important part of a microprocessor is the central processing unit (CPU), which consists of a number of electrical circuits. The CPU coordinates all of the computer's activities. It contains areas called registers that are capable of temporary data storage. Special functions are assigned to specific registers. For example, one register may be designated to hold the next instruction (program counter), while another register may be designated to receive only the results of the last operation performed (accumulator).

Directly attached to the CPU is the computer's main memory. The memory is the computer's method of storing data. In the microprocessor, some memory is integrated with the CPU, but here we refer to memory comprised of memory chips. The computer memory is divided into two categories: random access memory (RAM) and read only memory (ROM). RAM and ROM differ in that in RAM, the data can be changed and are stored only as long as there is a continuous power supply, whereas in ROM the data have been programmed ("burned in ROM"), cannot be changed, and are not dependent on electrical power to maintain memory. The capacity of the ROM and RAM is determined by the number of bytes of data that can be stored in the specific memory chip or set of chips. The units are bytes, kilobytes, (1 Kbyte = 1024 bytes), megabytes (1 Mbyte = 1024 x 1024 bytes), and gigabits (1 Gbyte = 1024 x 1 Mbytes). The computer can obtain and manipulate data from both RAM and ROM memory; however, results can be stored only in RAM.

The speed at which a microprocessor is able to process information is determined by the clock-speed. The faster the clock-speed, the more rapidly the computer is able to execute functions. Thus, a microcomputer with a clock-speed of 25 MHz is approximately five times faster than the original IBM-PC, which had a clock-speed of 4.77 MHz.

A coprocessor is a piece of hardware that can be added to a computer to speed up its functions. The coprocessor can relieve the main microprocessor of tasks it was not specifically designed to perform. It can also allow multiple processors to be connected in parallel and cooperate in the execution of programs. Many computers incorporate a math coprocessor, which is useful when it is necessary to perform extensive mathematical calculations, for example, in a large spreadsheet program.

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