The microprocessor is sometimes confused with its famous offspring, the microcomputer. A keyboard, video monitors, and memory were attached to the microprocessor: Power was added and the microcomputer was born! Suddenly, owning a computer became an economic reality for individuals and small businesses. People in most cases can count on a micro or its successor being within arm’s reach most cases of their working lives. In fact, many workers at the San Francisco-based McKesson Corporation already wear their PCs on their arms – literally!
There is no commonly accepted definition of a microcomputer or for that matter, of a minicomputer or a supercomputer. A microcomputer is just a small computer. However, it is a safe bet that any computer you can pick up and carry is probably a micro. But don’t be misled by the micro prefix. You can pick up and carry some very powerful computers!
The System Board. In a microcomputer, the microprocessor, the electronic circuitry for handling input/output signals from the peripheral devices (keyboard, printer, and so on), and the memory chips are mounted on a single circuit board called system board, or motherboard. Before being attached to the system board, the microprocessor and other chips are mounted onto a carrier. Carriers have standard-sized pin connectors that allow the chips to be attached to the system board.
The system board, the “guts” of a microcomputer, is what distinguishes one microcomputer from another. The central component of the system board, the microprocessor, is not made by the manufacturers of micros. It is made by companies, such as Motorola and Intel, that specialize in the development and manufacture of microprocessor. All of Apple’s Macintosh-series micros use Motorola 68000 in earlier models, the Motorola 68020 in the Macintosh II, and the Motorola 68030 in recent models.