- For small modern computers, see Small form factor
Small Form Factor is a generic term originally phrased as shuttle form factor, and originally meant to describe shoebox-sized personal computers with exactly two expansion slots...
, nettopNettop may refer to:*Nettop, a type of computer*NetTop, a NSA project...
, etc.
A
microcomputer is a
computerA computer is a machine that manipulates data according to a set of instructions.Although mechanical examples of computers have existed through much of recorded human history, the first electronic computers were developed in the mid-20th century . These were the size of a large room, consuming as...
with a
microprocessorA microprocessor incorporates most or all of the functions of a central processing unit on a single integrated circuit . The first microprocessors emerged in the early 1970s and were used for electronic calculators, using binary-coded decimal arithmetic on 4-bit words...
as its
central processing unitThe Central Processing Unit or processor is the portion of a computer system that carries out the instructions of a computer program, and is the primary element carrying out the computer's functions. This term has been in use in the computer industry at least since the early 1960s...
. Another general characteristic of these computers is that they occupy physically small amounts of space when compared to
mainframeMainframes are computers used mainly by large organizations for critical applications, typically bulk data processing such as census, industry and consumer statistics, enterprise resource planning, and financial transaction processing.The term probably had originated from the early mainframes, as...
and
minicomputerA minicomputer is a class of multi-user computers that lies in the middle range of the computing spectrum, in between the largest multi-user systems and the smallest single-user systems...
s. Many microcomputers (when equipped with a keyboard and screen for input and output) are also
personal computerA personal computer is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end user, with no intervening computer operator...
s (in the generic sense).
The abbreviation "
micro" was common during the 1970s and 1980s,(i) Direct reference: Jack Kibble-White, Jack
"Stand by for a Data-Blast", Off the Telly. Article written December 2005, retrieved 2006-12-15.
(ii) Usage in the titles of
Christopher EvansDr Christopher Riche Evans was a British psychologist, computer scientist, and author.A Welshman and the nephew of writer Caradoc Evans, Evans received his PhD. in psychology from Duke University in the US, and was a frequent guest on radio and television...
' books
"The Mighty Micro" (ISBN 0-340-25975-2) and
"The Making of the Micro" (ISBN 0-575-02913-7). Other books include Usborne's
"Understanding the Micro" (ISBN 0-86020-637-8), a children's guide to microcomputers. but has now fallen out of common usage.
Origins
The term "Microcomputer" came into popular use after the introduction of the
minicomputerA minicomputer is a class of multi-user computers that lies in the middle range of the computing spectrum, in between the largest multi-user systems and the smallest single-user systems...
, although
Isaac AsimovIsaac Asimov , was an American author and professor of biochemistry, best known for his works of science fiction and for his popular science books...
used the term microcomputer in his short story "The Dying Night" as early as 1956 (published in
The Magazine of Fantasy and Science Fiction in July that year). Most notably, the microcomputer replaced the many separate components that made up the minicomputer's CPU with a single integrated microprocessor
chipIn electronics, an integrated circuit is a miniaturized electronic circuit that has been manufactured in the surface of a thin substrate of semiconductor material...
.
The earliest models often sold as kits to be assembled by the user, and came with as little as 256
byteA byte is a unit of information storage representing the smallest addressable element for a given computer architecture. It often designates a sequence of bits whose length is determined by the architecture...
s of RAM, and no
input/outputIn computing, input/output, or I/O, refers to the communication between an information processing system , and the outside world – possibly a human, or another information processing system. Inputs are the signals or data received by the system, and outputs are the signals or data sent from it...
devices other than indicator lights and switches. However, as microprocessors and
semiconductor memorySemiconductor memory is an electronic data storage device, often used as computer memory, implemented on a semiconductor-based integrated circuit. Examples of semiconductor memory include non-volatile memory such as Read-only memory , magnetoresistive random access memory , and flash memory...
became less expensive from the early-to-mid-1970s onwards, microcomputers in turn grew faster and cheaper. This resulted in an explosion in their popularity during the late 1970s and early 1980s.
A large number of computer manufacturers packaged microcomputers for use in small business applications. By 1979, many companies such as
CromemcoCromemco was a Mountain View, California microcomputer company known for its high-end Z80-based S-100 bus computers in the early days of the home computer revolution. The Cromemco Dazzler was the first color graphics card available for personal computers....
,
Processor TechnologyProcessor Technology Corporation was a microcomputer company founded by Bob Marsh in April 1975.-History:Bob Marsh, Lee Felsenstein and Gordon French started designing the Sol-20 Terminal Computer in June 1975. The SOL-20 utilized the Intel 8080 8-bit microprocessor chip, running at 2 MHz...
, IMSAI,
NorthstarNorthstar is a fictional character, a superhero who appears in comic books published by Marvel Comics. Through his mutation, Northstar gains superhuman powers, which he uses for the betterment of society. Although originally a member of Alpha Flight, a fictional team of Canadian superhumans,...
,
Southwest Technical Products CorporationThe U.S. company SWTPC started in 1964 as DEMCO . It was incorporated in 1967 as Southwest Technical Products Corporation of San Antonio, Texas...
,
Ohio ScientificOhio Scientific Inc. was a United States computer company that built and marketed computers from the late 1970s to the early 1980s...
,
AltosAltos is a district and locality of the Cordillera Department, Paraguay.-Etymology:It is also called “Altos de Ybypytaré”, which in Guaraní means “path of the wind”, previously called “San Lorenzo de la Cordillera de los Altos”, one of the oldest cities of Paraguay...
, Morrow Designs and others produced systems designed either for a resourceful end user or consulting firm to deliver business systems such as accounting, database management, and word processing to small businesses. This allowed businesses unable to afford leasing of a minicomputer or time-sharing service the opportunity to automate business functions, without (usually) hiring a full-time staff to operate the computers. A representative system of this era would have used an S100 bus, an 8-bit processor such as a
Intel 8080The Intel 8080 was an early microprocessor designed and manufactured by Intel. The 8-bit microprocessor was released in April 1974 running at 2 MHz , and is generally considered to be the first truly usable microprocessor...
or
Zilog Z80The Zilog Z80 is an 8-bit microprocessor designed and sold by Zilog from July 1976 onwards. It was widely used both in desktop and embedded computer designs as well as for military purposes...
, and either
CP/MCP/M is an operating system originally created for Intel 8080/85 based microcomputers by Gary Kildall of Digital Research, Inc...
or
MP/MMP/M was the multi-user version of the CP/M operating system, created by Digital Research developer Tom Rolander in 1979. It allowed multiple users to connect to a single computer, each using a separate terminal....
operating system.
The increasing availability and power of
desktop computerA desktop computer is a personal computer in a form intended for regular use at a single location, as opposed to a mobile laptop or portable computer. Prior to the wide spread of microprocessors, a computer that could fit on a desk was considered remarkably small...
s for personal use attracted the attention of more software developers. As time went on and the industry matured, the market for
personal (micro)computerA personal computer is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end user, with no intervening computer operator...
s standardized around
IBM PC compatibleIBM PC compatible computers are those generally similar to the original IBM PC, XT, and AT. Such computers used to be referred to as PC clones, or IBM clones since they almost exactly duplicated all the significant features of the PC architecture, facilitated by various manufacturers' ability to...
s running
MS-DOSMS-DOS is an operating system developed by Microsoft. It was the most commonly used member of the DOS family of operating systems and was the main operating system for personal computers during the 1980s. It was preceded by M-DOS , designed and copyrighted by Microsoft in 1979...
(and later
WindowsMicrosoft Windows is a series of software operating systems and graphical user interfaces produced by Microsoft. Microsoft first introduced an operating environment named Windows in November 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces...
).
Modern desktop computers,
video game consoleA video game console is an interactive entertainment computer or electronic device that produces a video display signal which can be used with a display device to display a video game...
s,
laptopA laptop is a personal computer designed for mobile use and small and light enough to sit on one's lap while in use. A laptop integrates most of the typical components of a desktop computer, including a display, a keyboard, a pointing device , speakers, and often including a battery, into a single...
s,
tablet PCIn general terms, tablet PC refers to a laptop or slate-shaped mobile computer, equipped with a touchscreen or graphics tablet/screen hybrid to operate the computer with a stylus or digital pen, or a fingertip, instead of a keyboard or mouse....
s, and many types of
handheld deviceA mobile device is a pocket-sized computing device, typically having a display screen with touch input or a miniature keyboard. In the case of the personal digital assistant the input and output are combined into a touch-screen interface...
s, including
mobile phoneA mobile phone or mobile is a long-range, electronic device used for mobile telecommunications...
s and
pocket calculatorA calculator is a device that is used for performing mathematical calculations. It differs from a computer by having a limited problem solving ability and an interface optimized for interactive calculation rather than programming...
s, as well as industrial
embedded systemAn embedded system is a computer system designed to perform one or a few dedicated functions , often with real-time computing constraints. It is embedded as part of a complete device often including hardware and mechanical parts. In contrast, a general-purpose computer, such as a personal...
s, may all be considered examples of microcomputers according to the definition given above.
Colloquial use of the term
Everyday use of the expression "microcomputer" (and in particular the "micro" abbreviation) has declined significantly from the mid-1980s onwards, and is no longer commonplace. It is most commonly associated with the first wave of all-in-one
8-bitEight-bit CPUs normally use an 8-bit data bus and a 16-bit address bus which means that their address space is limited to 64 KB. This is not a "natural law", however, so there are exceptions....
home computerHome computer was a class of personal computer entering the market in 1977 and becoming increasingly common during the 1980s. They were marketed to consumers as accessible personal computers, more capable than video game consoles...
s and small business microcomputers (such as the Apple II,
Commodore 64The Commodore 64 is an 8-bit home computer introduced by Commodore International in January, 1982. Volume production started sometime in the spring of 1982, with machines being released on to the market in August at a price of US$ 595...
,
BBC MicroThe BBC Microcomputer System, or BBC Micro, was a series of microcomputers and associated peripherals designed and built by Acorn Computers for the BBC Computer Literacy Project, operated by the British Broadcasting Corporation...
, and TRS 80). Although—or perhaps because—an increasingly diverse range of modern microprocessor-based devices fit the definition of "microcomputer," they are no longer referred to as such in everyday speech.
In common usage, "microcomputer" has been largely supplanted by the description "
personal computerA personal computer is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end user, with no intervening computer operator...
" or "PC," which describes that it has been designed to be used by one person at a time. IBM first promoted the term "personal computer" to differentiate themselves from other microcomputers, often called "
home computerHome computer was a class of personal computer entering the market in 1977 and becoming increasingly common during the 1980s. They were marketed to consumers as accessible personal computers, more capable than video game consoles...
s", and also IBM's own mainframes and minicomputers. Unfortunately for IBM, the microcomputer itself was widely imitated, as well as the term. The component parts were commonly available to manufacturers and the
BIOSIn IBM PC Compatible computers, the basic input/output system , also known as the System BIOS, is a de facto standard defining a firmware interface. The BIOS is boot firmware, designed to be the first code run by a PC when powered on...
was reverse engineered through cleanroom design techniques.
IBM PC compatibleIBM PC compatible computers are those generally similar to the original IBM PC, XT, and AT. Such computers used to be referred to as PC clones, or IBM clones since they almost exactly duplicated all the significant features of the PC architecture, facilitated by various manufacturers' ability to...
"clones" became commonplace, and the terms "Personal Computer," and especially "PC" stuck with the general public.
Since the advent of
microcontrollerA microcontroller is a small computer on a single integrated circuit consisting of a relatively simple CPU combined with support functions such as a crystal oscillator, timers, watchdog timer, serial and analog I/O etc. Program memory in the form of NOR flash or OTP ROM is also often included on...
s (monolithic integrated circuits containing RAM, ROM and CPU all onboard), the term "micro" is more commonly used to refer to that meaning.
Description
Monitors, keyboards and other devices for input and output may be integrated or separate. Computer memory in the form of
RAM-Ram, ram, or RAM as a non-acronymic word:As a non-acronymic word Ram, ram, or RAM may refer to:-Animals:*Bighorn Sheep, A North American mountain sheep species*Sheep, an uncastrated male of which is called a ram...
, and at least one other less volatile, memory storage device are usually combined with the CPU on a system bus in a single unit. Other devices that make up a complete microcomputer system include, batteries, a
power supplyPower supply is a reference to a source of electrical power. A device or system that supplies electrical or other types of energy to an output load or group of loads is called a power supply unit or PSU...
unit, a keyboard and various input/output devices used to convey information to and from a human operator (
printersIn computing, a printer is a peripheral which produces a hard copy of documents stored in electronic form, usually on physical print media such as paper or transparencies. Many printers are primarily used as local peripherals, and are attached by a printer cable or, in most newer printers, a USB...
,
monitorsA monitor or display is a piece of electrical equipment which displays images generated by devices such as computers, without producing a permanent record. The monitor comprises the display device, circuitry, and an enclosure...
, human interface devices) Microcomputers are designed to serve only a single user at a time, although they can often be modified with software or hardware to concurrently serve more than one user. Microcomputers fit well on or under desks or tables, so that they are within easy access of the user. Bigger computers like
minicomputerA minicomputer is a class of multi-user computers that lies in the middle range of the computing spectrum, in between the largest multi-user systems and the smallest single-user systems...
s,
mainframesMainframes are computers used mainly by large organizations for critical applications, typically bulk data processing such as census, industry and consumer statistics, enterprise resource planning, and financial transaction processing.The term probably had originated from the early mainframes, as...
, and
supercomputerA supercomputer is a computer that is at the frontline of current processing capacity, particularly speed of calculation. Supercomputers were introduced in the 1960s and were designed primarily by Seymour Cray at Control Data Corporation , and led the market into the 1970s until Cray left to form...
s take up large cabinets or even a dedicated room.
A microcomputer comes equipped with at least one type of data storage, usually
RAMRandom-access memory is a form of computer data storage. Today, it takes the form of integrated circuits that allow stored data to be accessed in any order...
. Although some microcomputers (particularly early 8-bit home micros) perform tasks using RAM alone, some form of secondary storage is normally desirable. In the early days of home micros, this was often a data
cassette deckA cassette deck is a type of tape recorder for playing or recording audio compact cassettes. A deck was formerly distinguished from a recorder as being part of a stereo component system, while a recorder had a self-contained power amplifier...
(in many cases as an external unit). Later, secondary storage (particularly in the form of
floppy diskA floppy disk is a data storage medium that is composed of a disk of thin, flexible magnetic storage medium encased in a square or rectangular plastic shell. Floppy disks are read and written by a floppy disk drive or FDD, the initials of which should not be confused with "fixed disk drive," which...
and
hard diskA hard disk drive is a non-volatile storage device that stores digitally encoded data on rapidly rotating platters with magnetic surfaces. Strictly speaking, "drive" refers to the motorized mechanical aspect that is distinct from its medium, such as a tape drive and its tape, or a floppy disk...
drives) were built in to the microcomputer case itself.
History
Although they contained no microprocessors but were built around TTL logic,
Hewlett-PackardHewlett-Packard Company , commonly referred to as HP, is a technology corporation headquartered in Palo Alto, California, United States. HP has its United States offices at the former old Compaq Campus in unincorporated Harris County, Texas, Latin America offices in Miami-Dade County, Florida,...
Calculators as far back as 1968 had various levels of programmability such that they could be called microcomputers. The HP 9100B (1968) had rudimentary conditional (IF) statements, statement line numbers, Jump statements (Go to), registers that could be used as variables, and primitive subroutines. The programming language resembled
Assembly languageAssembly languages are a family of low-level languages for programming computers, microprocessors, microcontrollers, and other integrated circuits. They implement a symbolic representation of the numeric machine codes and other constants needed to program a particular CPU architecture...
in many ways. Later models incrementally added more features, including the
BASICIn computer programming, BASIC is a family of high-level programming languages. The original BASIC was designed in 1964 by John George Kemeny and Thomas Eugene Kurtz at Dartmouth in New Hampshire, USA to provide computer access to non-science students...
programming language (HP 9830A in 1971). Some models had tape storage and small printers. However, displays were limited to a single line at a time.
http://www.hpmuseum.org/ The HP 9100A was referred to as a
personal computerA personal computer is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end user, with no intervening computer operator...
in an advertisement in a 1968
ScienceScience is the academic journal of the American Association for the Advancement of Science and is considered one of the world's most prestigious scientific journals. The peer-reviewed journal, first published in 1880 is circulated weekly and has a print subscriber base of around 130,000...
magazine but that advertisement was quickly dropped. It is suspected that HP was reluctant to call them "computers" because it would complicate government procurement and export procedures.
The
Datapoint 2200The Datapoint 2200 was a mass-produced programmable terminal announced by Computer Terminal Corporation in June, 1970 . It was intended by its designers simply to be a versatile, cost-efficient terminal for connecting to a wide variety of mainframes by loading various terminal emulations from...
, made by
CTCDatapoint Corporation, originally known as Computer Terminal Corporation , was a computer company based in San Antonio, Texas, United States. Founded in 1967 by Phil Ray, Gus Roche and Jerry Martin, its first products were, as the company's initial name suggests, computer terminals...
in 1970, is perhaps the best candidate for the title of "first microcomputer". While it contains no microprocessor, it used the
4004The Intel 4004 is a 4-bit central processing unit released by Intel Corporation in 1971. The 4004 is the first complete CPU on one chip, the first commercially available microprocessor, a feat made possible by the use of the new silicon gate technology allowing the integration of a higher number...
programming
instruction setAn instruction set is a list of all the instructions, and all their variations, that a processor can execute.Instructions include:* Arithmetic such as add and subtract...
and its custom TTL logic was the basis for the
Intel 8008The Intel 8008 was an early byte-oriented microprocessor designed and manufactured by Intel and introduced in April 1972. It was an 8-bit CPU with an external 14-bit address bus that could address 16KB of memory...
, and for practical purposes the system behaves approximately as if it contains an 8008. This is because Intel was the contractor in charge of developing the Datapoint's CPU but ultimately CTC rejected the 8008 design because it needed 20 support chips.
Another early system, the
Kenbak-1The Kenbak-1 is considered by the Computer History Museum and the American Computer Museumto be the world's first "personal computer" . Little information is recorded regarding the Kenbak-1, as around only 40 machines were ever built and sold...
, was released in 1971. Like the Datapoint 2200, it used discrete TTL logic instead of a microprocessor, but functioned like a microcomputer in most ways. It was marketed as an educational and hobbyist tool, but was not a commercial success; production ceased shortly after introduction.
http://www.vintage-computer.com/kenbak-1.shtml. Another system of note is the
Micral-NAccording to the Computer History Museum, the Micral N was the earliest commercial, non-kit personal computer based on a microprocessor, the Intel 8008....
, introduced in 1973 by a French company and powered by the 8008; it was the first microcomputer sold all assembled and not as a construction kit.
Virtually all early microcomputers were essentially boxes with lights and switches; one had to read and understand binary numbers and machine language to program and use them (the Datapoint 2200 was a striking exception, bearing a modern design based around a monitor, keyboard, and tape and disk drives). Of the early "box of switches"-type microcomputers, the MITS
Altair 8800The MITS Altair 8800 was a microcomputer design from 1975, based on the Intel 8080 CPU and sold as a mail-order kit through advertisements in Popular Electronics, Radio-Electronics and other hobbyist magazines. The designers intended to sell only a few hundred to hobbyists, and were surprised when...
(1975) was arguably the most famous. Most of these simple, early microcomputers were sold as
electronic kitsAn electronic kit is a package of electrical components used to build an electronic device. Generally, kits are comprised of electronic components, a circuit diagram , assembly instructions and often a PCB. People primarily purchase electronic kits to have fun and learn how things work...
--bags full of loose components which the buyer had to solder together before the system could be used.
The period from about 1971 to 1976 is sometimes called the first generation of microcomputers. These machines were for engineering development and hobbyist personal use. In 1975, the
Processor TechnologyProcessor Technology Corporation was a microcomputer company founded by Bob Marsh in April 1975.-History:Bob Marsh, Lee Felsenstein and Gordon French started designing the Sol-20 Terminal Computer in June 1975. The SOL-20 utilized the Intel 8080 8-bit microprocessor chip, running at 2 MHz...
SOL-20 was designed, which consisted of a single board which included all the parts of the computer system. The SOL-20 had built-in EPROM software which elimated the need for rows of switches and lights. The
MITS AltairThe MITS Altair 8800 was a microcomputer design from 1975, based on the Intel 8080 CPU and sold as a mail-order kit through advertisements in Popular Electronics, Radio-Electronics and other hobbyist magazines. The designers intended to sell only a few hundred to hobbyists, and were surprised when...
just mentioned played an instrumental role in sparking significant hobbyist interest, which itself eventually led to the founding and success of many well-known
personal computerA personal computer is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end user, with no intervening computer operator...
hardware and software companies, such as
MicrosoftMicrosoft Corporation is a multinational computer technology corporation that develops, manufactures, licenses, and supports a wide range of software products for computing devices...
and
Apple ComputerApple Inc. is an American multinational corporation that designs and manufactures consumer electronics and computer software products. The company's best-known hardware products include Macintosh computers, the iPod and the iPhone...
. Although the Altair itself was only a mild commercial success, it helped spark a huge industry.
1977 saw the introduction of the second generation, known as
home computerHome computer was a class of personal computer entering the market in 1977 and becoming increasingly common during the 1980s. They were marketed to consumers as accessible personal computers, more capable than video game consoles...
s. These were considerably easier to use than their predecessors, whose operation often demanded thorough familiarity with practical electronics. The ability to connect to a monitor (screen) or TV set allowed for visual manipulation of text and numbers. The BASIC programming language, which was easier to learn and use than raw machine language, became a standard feature. These features were already common in
minicomputerA minicomputer is a class of multi-user computers that lies in the middle range of the computing spectrum, in between the largest multi-user systems and the smallest single-user systems...
s, which many hobbyists and early manufactures were familiar with.
1979 saw the launch of the
VisiCalcVisiCalc was the first spreadsheet program available for personal computers. It is often considered the application that turned the microcomputer from a hobby for computer enthusiasts into a serious business tool...
spreadsheetA spreadsheet is a computer application that simulates a paper worksheet. It displays multiple cells that together make up a grid consisting of rows and columns, each cell containing either alphanumeric text or numeric values...
(initially for the Apple II) that first turned the microcomputer from a hobby for computer enthusiasts into a business tool. After the 1981 release by IBM of their
IBM PCThe IBM Personal Computer, commonly known as the IBM PC, is the original version and progenitor of the IBM PC compatible hardware platform. It is IBM model number 5150, and was introduced on August 12, 1981...
, the term
Personal ComputerA personal computer is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end user, with no intervening computer operator...
became generally used for microcomputers compatible with the IBM PC architecture (PC compatible).
See also
- Personal Computer
A personal computer is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end user, with no intervening computer operator...
- Lists of microcomputers
- Minicomputer
A minicomputer is a class of multi-user computers that lies in the middle range of the computing spectrum, in between the largest multi-user systems and the smallest single-user systems...
- Mainframe computer
Mainframes are computers used mainly by large organizations for critical applications, typically bulk data processing such as census, industry and consumer statistics, enterprise resource planning, and financial transaction processing.The term probably had originated from the early mainframes, as...
- Supercomputer
A supercomputer is a computer that is at the frontline of current processing capacity, particularly speed of calculation. Supercomputers were introduced in the 1960s and were designed primarily by Seymour Cray at Control Data Corporation , and led the market into the 1970s until Cray left to form...
- History of computing hardware (1960s-present)
The history of computing hardware starting at 1960 is marked by the conversion from vacuum tube to solid state devices such as the transistor and later the integrated circuit. By 1959 discrete transistors were considered sufficiently reliable and economical that they made further vacuum tube...