microcomputer  is a small, relatively inexpensive computer with a microprocessor and its central processing unit (CPU).  [2]  It includes a microprocessor, memory, and minimal input / output (I / O) circuitry mounted on a single printed circuit board .  [3]  Microcomputers became popular in the 1970s and 1980s with the advent of increasingly powerful microprocessors. The predecessors to these computers, mainframes and minicomputers , were comparatively much larger and more expensive (though indeed present-day mainframes such as the IBM System zmachines use one or more custom microprocessors and their CPUs). Many microcomputers (when equipped with a keyboard and screen for input and output) are also personal computers(in the generic sense).  [4]

The abbreviation  micro  Was Common During the 1970s and 1980s,  [5]  aim HAS now fallen out of common use.


The term  microcomputer  cam into popular use partner after the introduction of the minicomputer , ALTHOUGH Isaac Asimov used the term In His short story “The Dying Night” as early as 1956 (published in  The Magazine of Fantasy and Science Fiction  in July That year).  [6]  Most notably, the microcomputer is one of the few components that make up the minicomputer’s CPU with one integrated microprocessor chip .

The first microcomputer was the Japanese Sord Computer Corporation’s SMP80 / 08 (1972), which was followed by the SMP80 / x (1974).  [7]  The French developers of the Micral N (1973) filed their patents with the term “Microcomputer”, a literal equivalent of “Microcomputer”, to designate a solid state machine designed with a microprocessor. In the USA, the Earliest models Such as the Altair 8800 Were Often sold as kits to be assembled by the user, and cam with as little as 256 bytes of RAM , and no input / output devices other than indicator lights and switches, useful as a proof of conceptto demonstrate what such a simple device could do.  [8]  However, as microprocessors and semiconductor memory become cheaper, microcomputers in turn grow cheaper and easier to use:

  • Increasingly inexpensive logic chips Such As the 7400 series allowed cheap dedicated circuitry for Improved user interfaces Such As keyboard input, INSTEAD of simply a row of switches to toggle bits one at a time.
  • Use of audio cassettes for inexpensive data storage.
  • Large cheap arrays of silicon logic gates in the form of read-only memory and EPROMs allowed utility programs and self- booting kernels to be stored within microcomputers. These Stored programs Could automatically load further Top more complex software from external storage devices without user intervention to form an inexpensive turnkey system That does not require a computer expert To Understand gold to use the device.
  • Random access memory becomes cheap enough to afford dedicating about 1-2 kilobytes of memory to a video display controller frame buffer , for a 40×25 or 80×25 text display or blocky color graphics on a common household television . This replaced the slow, complex, and expensive teletypewriter that has been previously used as an interface to minicomputers and mainframes.

All these improvements in cost and usability resulted in an explosion in their popularity during the late 1970s and early 1980s. A large number of computer makers packaged microcomputers for use in small business applications. By 1979, many companies such as Cromemco , Processor Technology , IMSAI , North Star Computers , Southwest Technical Products Corporation , Ohio Scientific , Altos Computer Systems , Morrow Designsand others produced systems à la calculus de la recherche et de la gestion de la gestion et de la gestion et de la gestion de la gestion. This is a business that can not afford to be able to afford a time-sharing service or the opportunity to automate business functions, without hiring a full-time staff to operate the computers. A representative system would have used an S100 bus , an 8-bit processor such as an Intel 8080 or Zilog Z80 , and either CP / M or MP / M operating system. The availability and power of desktop computersfor personal use attracted the attention of more software developers. In time, and as the industry matured, the market for personal computers standardized around IBM compatible PCs running DOS , and later Windows . Computers, video game consoles , laptops , tablet PCs , and many types of handheld devices , including mobile phones , pocket calculators , and industrial embedded systems , may be considered examples of microcomputers according to the definition given above.

Colloquial use of the term

Everyday use of the phrase “microcomputer” (and in particular the “micro” abbreviation) has declined significantly from the mid-1980s and has declined in commonplace use since 2000.  [9]  The term is most commonly associated with the first wave of all -in-one 8-bit home computers and small business microcomputers (such as the Apple II , Commodore 64 , BBC Micro , and TRS 80 ). Although, because of a diverse range of modern microprocessor-based devices 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 term ” personal computer ” or “PC”, which specifies a computer that has been designed to be used by the individual at a time, a term first coined in 1959.  [10] ]  IBM first Promoted the term “personal computer” to Differentiate Themselves from other microcomputers, Often called ” home computers “, and aussi IBM’s own mainframes and minicomputers.  citation needed  ]  However, following its release, the IBM PC itself was widely imitated, as well as the term.through cleanroom design techniques. IBM PC-compatible “clones” became commonplace, and the terms “personal computer”, and especially “PC”, stuck with the general public, often specifically for a DOS or (nowadays) Windows-compatible computer.

Since the advent of microcontrollers (monolithic integrated circuits containing RAM, ROM and CPU all onboard), the term “micro” is more commonly used to refer to that meaning.  quote needed  ]


Monitors, keyboards and other devices for input and output may be integrated or separate. Computer memory in the form of RAM , and at least one other less volatile, memory storage device are usually combined with the CPU on a system bus in one unit. That Other devices make up a full microcomputer system include batteries, a power supply unit, a keyboard and various input / output devices used to Convey information to and from a human operator ( printers , monitors , human interface devices). Microcomputers are designed to be used at a time, they can often be modified with software or hardware. Microcomputers fit well under or under desks or tables, so they are within easy access of users. Bigger computers like minicomputers , mainframes , and supercomputers take up wide offices or Even dedicated rooms.

A microcomputer comes with at least one type of data storage, usually RAM . 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 microphones, this was often a data cassette deck (in many cases as an external unit). Later, secondary storage (particularly in the form of floppy disk and hard disk drives) were built into the microcomputer case.


TTL precursors

Although they did not contain any microprocessors, they were built around transistor-transistor logic (TTL), Hewlett-Packard calculators as far back as 1968 had various levels of programmability comparable to 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 language language resembled assembly language in many ways. Later models were added more features, including BASIC programming language (HP 9830A in 1971). Some models had tape storage and small printers. However, displays were limited to one line at a time. [1]The HP 9100A Was Referred to as a personal computer in an advertisement in a 1968 Science magazine  [11]  goal advertisement That Was Quickly dropped.  [12] HP has been reluctant to sell them as “computers” because the perception has been that it has become so powerful, and thus has decided to market them as calculators. In addition, it is more likely to buy calculators than computers and the method of calculating the purchase of a computer. HP virtual museum

The Datapoint 2200 , made by CTC in 1970, was also comparable to microcomputers. While it contains no microprocessor, the instruction set of its custom is the basis of the instruction set for the Intel 8008 , and for practical purposes the system behaves approximately as if it contains an 8008. of developing the Datapoint’s CTC rejected the 8008 design because it needed 20 support chips.  [13]

Another early system, the Kenbak-1 , was released in 1971. Like the Datapoint 2200, it used a discrete transistor-transistor logic instead of a microprocessor, but it is a function of microcomputer in some ways. It was marketed as an educational and hobbyist tool, but it was not a commercial success; production ceased shortly after introduction.  [14]

Early microcomputers

In late 1972, a French team headed by François Gernelle within a small company, Réalisations & Etudes Electroniques (R2E), developed and patented a computer based microprocessor – the Intel 8008 8-bit microprocessor. This Micral-N was marketed in early 1973 as a “microcomputer” or  microcomputer  , mainly for scientific and process-control applications. About Micral-Nwere installed in the next two years, followed by a new version based on Intel 8080. Meanwhile, another French team developed the Alvan, a small computer for office automation which found customers in banks and other sectors. The first version was based on LSI chips with an 8008 Intel as a peripheral controller (keyboard, monitor and printer), before adopting the Zilog Z80 as a main processor.

In late 1972, a Sacramento State University team led by Bill Pentz built the Sac State 8008 computer,  [15]  able to handle thousands of patients’ medical records. The State 8008 Bag was designed with the Intel 8008. It has a full set of hardware and software components: a disk operating system included in a series of programmable read-only memory chips (PROMs); 8 Kilobytes of RAM; IBM’s Basic Language Assembly (BAL); a hard drive; a color display; a printer output; a 150 bit / s serial interface for connecting to a mainframe; and even the world’s first microcomputer front panel.  [16]

In early 1973, Sord Computer Corporation (now Toshiba Personal Computer System Corporation ) completed the SMP80 / 08, which used the Intel 8008 microprocessor. The SMP80 / 08, however, did not have a commercial release. After the first general-purpose microprocessor, the Intel 8080 , was announced in April 1974, Sord announced the SMP80 / x, the first microcomputer to use the 8080, in May 1974.  [7]

Virtually all the early microcomputers were essentially boxes with lights and switches; (The Datapoint 2200 was a striking exception, bearing a modern design based on a monitor, keyboard, and tape drives). Of the early “box of switches” -type microcomputers, the MITS Altair 8800 (1975) was arguably the most famous. Most of these simple, early microcomputers were sold as electronic kits -bags full of loose components which the buyer had to sell together before the system could be used.

The period from about 1971 to 1976 is sometimes called the first generation of microcomputers. Many companies such as DEC ,  [17]  National Semiconductor ,  [18]  Texas Instruments  [19] offered their microcomputers for use in terminal control, peripheral device interface control and industrial machine control. There were also machines for engineering development and hobbyist personal use.  [20]  In 1975, the SOL-20 Processor Technology was designed, which incorporated part of the computer system. The SOL-20had built-in EPROM software which eliminates the need for rows of switches and lights. The MITS Altair just MENTIONED played an instrumental role in sparking significant hobbyist interest, qui Itself Eventually led to the founding and success of Many well-known personal computer hardware and software companies, Such As Microsoft and Apple Computer . Although the Altair itself was only a mild commercial success, it helped spark a huge industry.

Home computers

By 1977, the introduction of the second generation, known as home computers , made microcomputers more easily than their predecessors because of their predecessors’ operation often demanded thorough familiarity with practical electronics. The ability to connect to a monitor (screen) or TV set. The BASIC language, which was easier to learn and use than raw machine language, became a standard feature. These features were already common in minicomputers , with which many hobbyists and early products were familiar.

In 1979, the launch of the VisiCalc spreadsheet (initially for the Apple II ) first turned the microcomputer into a business tool. After the 1981 release by IBM icts of IBM PC , the term personal computer est devenu Generally used for microcomputers compliant with the IBM PC architecture ( PC compatible ).

See also

  • History of Computing Hardware (1960s-present)
  • Lists of microcomputers
  • Mainframe computer
  • minicomputer
  • Personal computer
  • Supercomputer

Notes and references

  1. Jump up^   Kahney, Leander (2003-09-09). “Great Price for a Modest PC” .  Wired . Lycos . Retrieved 2006-10-25 .
  2. Jump up^  “Microcomputer” . dictionary.com.
  3. Jump up^   AO, Williman; Jelinek, HJ (June 1976). “Special Tutorial: Introduction to LSI Microprocessor Developments” (Computer). IEEE: 37. doi : 10.1109 / CM.1976.218612 . ISSN  0018-9162 .
  4. Jump up^  An early use of the term personal computer in 1962 predates microprocessor-based designs.  (See “Personal Computer: Computers at Companies” below) . A microcomputer used as an embedded control system can have no human-readable input and output devices. “Personal computer” may be used generically or may denote anIBM PC compatiblemachine.
  5. Jump up^  Proof of “micro” as a once-common term:
    (i) Direct reference: Graham Kibble-White,”Standby for a Data-Blast”, Off the Telly. Article written December 2005, retrieved 2006-12-15.
    (ii) Use in the titles ofChristopher Evans’ 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.
  6. Jump up^   Asimov, Isaac (July 1956). “The Dying Night”.  The Magazine of Fantasy and Science Fiction  .
  7. ^ Jump up to: b  http://museum.ipsj.or.jp/en/computer/personal/0086.html
  8. Jump up^   Ceruzzi, Paul (2012).  Computing: concise history  . Cambridge, MA: MIT Press. p. 105. ISBN  9780262517676 .
  9. Jump up^  “microcomputer”. OED Online. December 2013. Oxford University Press. February 15, 2014.
  10. Jump up^  “personal computer”. OED Online. December 2013. Oxford University Press. February 15, 2014
  11. Jump up^  “Powerful Computing Genie” (PDF) . Retrieved 2012-08-30 .
  12. Jump up^  “Restoring the Balance Between Analysis and Computation” (PDF) . Retrieved 2012-08-30 .
  13. Jump up^  “MicroprocessorHistory” . Computermuseum.li. 1971-11-15 . Retrieved 2012-08-30 .
  14. Jump up^  “Kenbak-1” .  The Vintage Computer  .
  15. Jump up^  “Digibarn Stories: Bill Pentz and (Earliest) History of the Microcomputer (August 2008)” . Digibarn.com . Retrieved 2012-08-30 .
  16. Jump up^   Terdiman, Daniel (2010-01-08). “Inside the world’s long-lost first microcomputer | Geek Gestalt – CNET News” . News.cnet.com . Retrieved 2012-08-30 .
  17. Jump up^  “16-bit timeline” .
  18. Jump up^  “Paper Tape Readers Work With IMP Micros” .  Computerworld  . Oct. 23, 1974. p. 28.
  19. Jump up^  “Upward Compatible Software and Downward Compatible Price” .  Computerworld  . Dec. 10, 1975. p. 49.
  20. Jump up^  Computer Adventures  .

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