by Dinesh Thakur

A computer integrated onto a single piece of silicon or CHIP, often referred to informally as a microchip, or the silicon chip. The microprocessor was the invention that sparked the revolution in computing and communications which began in the late 1970s. The first commercial microprocessor was the Intel 4004 launched in 1971, which was designed to be used in a Japanese desk calculator.

Microprocessors lie at the heart of all modern computers, not only personal computers, and are also EMBEDDED as controllers in many industrial and domestic appliances, from cars to washing machines. A single microprocessor chip, together with some memory chips, forms the basis for a simple computer (and for some embedded applications may even have the memory integrated onto the same chip). The electronic components of a modern microprocessor chip are very densely packed, cramming some 100 million transistors onto a silicon die around 15 mm square, and this density rises with every generation (in accordance with MOORE'SLAW).

The main components of a typical microprocessor chip are: INTEGER and FLOATING POINT arithmetic units which actually perform the calculations; a bank of REGISTERS that hold both the numbers currently being worked on, and the results; an INSTRUCTION FETCH unit which gets tile next instructions to be executed from external memory; one or more CACHES to speed up access to data and instructions that are anticipated to be needed soon; and a CONTROLUNIT which choreographs the operations of all these other units. Together, these core units act as the central processing unit (CPU) of a computer. Mainstream microprocessors, such as those of the Intel PENTIUM or the POWERPC families, often integrate several additional functional units such as a MEMORYMANAGEMENT UNIT, INTERRUPT CONTROLLER and BUS control unit onto the chip. There is also a tendency toward adding special units and instructions to assist specific tasks such as graphics or sound processing.