Microcomputers became popular in the 1970s and 1980s with the advent of increasingly powerful microprocessors such as the MOS Technology 6502, Zilog Z80, and Intel 8088. The predecessors to these computers, mainframes and minicomputers, were comparatively much larger and more expensive.

The CPU design was released as the COSMAC in 1974 and several experimental machines using it were built in 1975, but RCA declined to market any of these until introducing the COSMAC Elf in 1976, in kit form. By this time a number of other machines had entered the market.

Microcomputers emerged in the 1970s and gained popularity with the introduction of the Altair 8800 and the Apple II. They were a significant departure from the larger and more expensive mainframe and minicomputer systems of that time.

His creation, “Control Program for Microcomputers” or CP/M, was a revelation. It standardized the way programs interacted with the hardware, allowing developers to create software that could run on multiple machines.

Building on this, personal microcomputers quickly appeared as hobbyist kits. In late 1974 MITS (Micro Instrumentation and Telemetry Systems) announced the Altair 8800, powered by the Intel 8080 chip. The Altair is often called the first commercially successful personal computer.

Introduced by Texas Instruments and Westinghouse in the early 1960s, came into real commercial use in 1964 with Fairchild Semiconductors 702 linear IC. The first desktop electronic calculators were introduced about 1963.

These two Micro Computer Systems (MCS) were aimed at two very different markets. One would eventually lead to the under $1 controller, the other would be the engine for a versatile personal computer (PC). By analogy it was like creating the “motorbike” and the “station wagon” at the same time.

On August 12, 1981, the shoe finally dropped. IBM announced the introduction of the Model 5150, thereby stepping into the microcomputer market and shaking the industry to its foundations. Though the term "personal computer" was already in use, at the time, it was synonymous with "microcomputer."

Intel delivered two different microcomputers five months apart: the MCS-4, emphasizing low cost, in November 1971, and the MCS-8, for versatility in April 1972.

The Apple II and the Commodore PET were both introduced at the first West Coast Computer Faire, which opened on April 16, 1977. The TRS-80 was announced on August 3, 1977. Here are pictures of these three computers, from early advertisements for them.