Personal Computer

History

Definitions

A computer is a machine that manipulates data according to a list of instructions.Personal computer: a computer whose original sales price, size, and capabilities make it useful for individuals, intended to be operated directly by an end user (one person).

Two Separate Technologies

automated calculation

programmability

Automated Calculation

Early mechanical calculating devices: abacus, slide rule, astrolabe

No programmability

History

In 1801, Joseph Marie Jacquard made an improvement to the textile loom that used a series of punched paper cards as a template to allow his loom to weave intricate patterns automatically. The resulting Jacquard loom was an important step in the development of computers because the use of punched cards to define woven patterns can be viewed as an early, albeit limited, form of programmability.

1837, Charles Babbage was the first to conceptualize and design a fully programmable mechanical computer that he called "The Analytical Engine". Due to limited finances, and an inability to resist tinkering with the design, Babbage never actually built his Analytical Engine.

Mainframes

Konrad Zuse's electromechanical "Z machines". The Z3 (1941) Atanasoff–Berry Computer (1941) British Colossus computer (1944) Harvard Mark I (1944)U.S. Army's Ballistics Research Laboratory ENIAC (1946)

The EDSAC eventually replaced the ENIAC machine

Minicomputers

Some of the first computers that might be called "personal" were early minicomputers: such as the LINC and PDP-8, and later on VAX and larger minicomputers from Digital Equipment Corporation (DEC), Data General, Prime Computer, and others.

Vacuum tube-based computers were in use throughout the 1950s, but were largely replaced in the 1960s by transistor-based devices, which were smaller, faster, cheaper, used less power and were more reliable.

Microprocessor and cost reduction

The minicomputer ancestors of the modern personal computer used early integrated circuit (microchip) technology, which reduced size and cost, but they contained no microprocessor. After the "computer-on-a-chip" was commercialized, the cost to manufacture a computer system dropped dramatically.

The arithmetic, logic, and control functions that previously occupied several costly circuit boards were now available in one integrated circuit, making it possible to produce them in high volume.

First Personal ComputersKenbak-1 Datapoint 2200 Altair 8800 IMSAI 8080 Heathkit and Zenith Apple II TRS-80 Commodore PET Atari 400/800 Vic 20 and Commodore 64