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.
• The Educ-8 (1975) was an Electronics Australia magazine project describing a computer built from TTL ICs.

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.

This is a sortable list; click on the icon at the top of each column to sort by the contents of that column.

Model	Processor	Year	Format	Remarks	Ref
Intel SIM8-01	Intel 8008	early 1972	bare board	Intel's developer kit for the 8008
MOS Technology KIM-1	MOS Technology 6502	1975	complete board	MOS's developer kit for the 6502, widely used in a number of projects
Motorola MEK6800D2	Motorola 6800	1976	complete board
Rockwell AIM-65	6502		complete board
Synertek SYM-1	6502	1978	complete board
Intel SDK-85	Intel 8085	1978

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.

This is a sortable list; click on the icon at the top of each column to sort by the contents of that column.

Model	Processor	Year	Format	Remarks	Ref
SCELBI	Intel 8008	1974		was the earliest commercial kit computer based on the Intel 8008 microprocessor. sold for embedded control applications.
Mark-8	Intel 8008	1974	Plans published, an etched board was available but constructors had to source all parts
MITS Altair 8800	Intel 8080	1975	Etched boards and parts	introduced S-100 bus
COSMAC ELF	RCA 1802	1976
Apple I	MOS Technology 6502	1976
Nascom, Nascom 1	Zilog Z80	1977
Nascom 2	Z80	1979
Telmac 1800	RCA 1802	1977
Newbear 77-68	Motorola 6800	1977
Heathkit H8	8080	1977	all parts, case and power supply, detailed instructions	Heathkit was a notable manufacturer of electronics kits
Heathkit H11	LSI-11	1977	all parts, case and power supply, detailed instructions	A 16-bit microcomputer compatible with a PDP 11
Electronics Australia 77up2 aka "Baby 2650	2650	1977
Netronics ELF II	RCA 1802	1977
Quest SuperELF	RCA 1802
Elektor TV Games Computer	Signetics 2650	1979
System 68	Motorola 6800	1977	Electronics today international magazine project
PSI comp 80	Z80	1979		by Powertran from a design in the magazine Wireless World
Science of Cambridge MK14	National Semiconductor SC/MP	1978		Low-cost kit expandable to video output
Acorn System 1	6502	1979
Tangerine Microtan 65	6502	1979		Rack-based extendible system
Compukit UK101	6502	1979	Practical Electronics magazine project (Clone of Ohio Scientific Superboard II)	BASIC in ROM
Sinclair's ZX80	Z80	1980		were among the last popular kit systems
Sinclair ZX81	Z80	1981		were among the last popular kit systems
MicroBee	Zilog Z80	1982		The computer was conceived as a kit, with assembly instructions included in Your Computer magazine, in February 1982.

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.
• Micral N (1973) was the earliest commercial, non-kit personal computer based on a microprocessor (the Intel 8008)
• 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.
• 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. 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

• A cached copy of the Department of Physics (2008-10-06). "Machine code programming" can be found on the internet archive at:
  • http://web.archive.org/web/20100216174218/http://kcl.ac.uk/content/1/c6/02/14/60/2ndyearmanual2008-2009lab1.pdf

External links

• Obsolete technology website — Information about many old computers.