List of early microcomputers

This is a list of early microcomputers sold to hobbyists and developers. These microcomputers were often sold as "DIY" kits or pre-built machines in relatively small numbers in the mid-1970s. These systems were primarily used for teaching the use of microprocessors and supporting peripheral devices, and unlike home computers were rarely used with pre-written application software. Most early micros came without alphanumeric keyboards or displays, which had to be provided by the user. RAM was quite small in the unexpanded systems (a few hundred bytes to a few kilobytes). By 1976 the number of pre-assembled machines was growing, and the 1977 introduction of the "Trinity" of Commodore PET, TRS-80 and Apple II generally marks the end of the "early" microcomputer era, and the advent of the consumer home computer era that followed.

Discrete logic

Before the advent of microprocessors, it was possible to build small computers using small-scale integrated circuits (ICs), where each IC contained only a few logic gates or flip-flops.

• The Kenbak-1 (1971) used discrete transistor-transistor logic ICs and had 256 bytes of memory. It was priced at USD 750 and sold only 40 units.^[1]
• The Educ-8 (1975) was an Electronics Australia magazine project describing a computer built from TTL ICs911.

Test and development machines

As microprocessors were developed, companies often released simple development systems to bootstrap the use of the processor. These systems were often converted by hobbyists into complete computer systems.

Kits

For some time the microcomputer world was dominated by systems delivered in kit form. As most machines of the era were sold in small numbers, there was no reason to invest in automated manufacturing systems, leaving the final assembly to manual labor. Kits took advantage of this by offering the system at a low price point, and relying on the user to complete the expensive part, the final assembly. Kits were popular between 1975, with the introduction of the famous Altair 8800, but as sales volumes increased, kits became less common. The introduction of useful fully assembled machines in 1977 led to the rapid disappearance of kit systems for most users. The famed ZX81 is among the last of the large sellers in the kit market.

Some magazines published plans and printed circuit board layouts from which a reader could in principle duplicate the project, although usually commercially made boards could be ordered to expedite assembly. Other kits varied from etched, drilled, printed circuit boards and a parts list to packages containing cases, power supplies, and all interconnections. All kits required significant assembly by the user.

Complete microcomputers

A number of complete microcomputers were offered even before kits became popular, dating to as far back as 1973. For some time there was a major market for assembled versions of the Altair 8800, a market that grew significantly through the late 1970s and into the early 1980s. The introduction of three computers aimed at personal users in 1977, the Radio Shack TRS-80, Apple II, and Commodore PET, significantly changed the market and led to the home computer revolution.

• Datapoint 2200 of 1970 (shipping 1971) was the first machine designed to use a microprocessor, but when Intel could not deliver the 8008 in time, they released the machine using discrete logic.
• MicroSystems International's CPS-1, using a locally produced microprocessor based on the design of the Intel 4004. First built in 1972, a small number shipped in early 1973.^[6]
• Micral N (1973) was the earliest commercial, non-kit personal computer based on a microprocessor (the Intel 8008)^[7]
• MCM/70 was a 1974 Intel 8008-based design, primarily designed to run APL. According to the IEEE Annals of Computer History, the MCM/70 is the earliest commercial, non-kit personal computer.^[8]
• IBM 5100 was possibly the first portable microcomputer. Most people think the famous IBM PC (the 5150) was IBM's first micro but there were a number of microcomputer models released by IBM from 1975.
• Processor Technology's Sol-20, offered both as kit and assembled, but the vast majority were sold assembled
• ECD Micromind, introduced 1977 MOS Technology 6512 (6502 w/ external clock). Prototypes only.
• MPT8080 Microtutor, an Intel 8080–based microprocessor trainer introduced 1977. As recently as 2008, it remained in academic use.^[9] As of 2011, the MPT8080 was still available for sale.
• Tesla PMI-80
• Ohio Scientific Model 500, 1978, 6502
• Exidy Sorcerer, 1978, Z80
• Explorer/85 8085, 1979

See also

• List of home computers
• List of home computers by video hardware
• Microprocessor development board
• Microcomputer Associates, Incorporated

References

Notes

External links

• Obsolete technology website — Information about many old computers.