Microcomputer
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Although there is no rigid definition, a microcomputer (sometimes shortened to micro[1]) is most often taken to mean a computer with a microprocessor (µP) as its CPU. Another general characteristic of these computers is that they occupy physically small amounts of space. Although the terms are not synonymous, many microcomputers are also personal computers (in the generic sense) and vice versa.[2][3]
The microcomputer came after the minicomputer, most notably replacing the many distinct components that made up the minicomputer's CPU with a single integrated microprocessor chip. The early microcomputers were primitive, the earliest models shipping with as little as 256 bytes of RAM, and no input / output other than lights and switches. However, as microprocessor design advanced rapidly and memory became less expensive from the early 1970s onwards, microcomputers in turn grew faster and cheaper. This resulted in an explosion in their popularity during the late 1970s and early 1980s.
The increasing availability and power of such computers attracted the attention of more software developers. As time went on and the industry matured, the market standardized around IBM PC clones running MS-DOS (and later Windows).
While still the microcomputer may have taken over from older-style designs in many cases, its most significant effects are to have widened access to computers, and to have expanded their usage into completely new areas.
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[edit] Definition
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Desktop computers, video game consoles, laptop computers, tablet PCs, and many types of handheld devices may all be considered examples of microcomputers according to the technical definition given above.
The word microcomputer traces back to the "Big iron" revolution. It described the first computers that were "personal-scale". They were small enough to fit on a desk (rather than in a server room) and cheap enough to be owned by an individual (instead of shared within a corporation, or a school).[citation needed] The advent of PCs that could run applications like "VisiCalc" put microcomputers into the workplace and started displacing the minicomputers and mainframes of the day. Clusters of microcomputers are even stealing the large scale jobs from mainframes.
[edit] 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-bit home computers and small business microcomputers (such as the Apple II, Commodore 64,BBC Micro, and TRS 80). Although—or perhaps because—an increasingly diverse range of modern microprocessor-based devices fit the technical definition of "microcomputer" given above, they are no longer referred to as such in everyday speech.
In common usage, "microcomputer" has been largely supplanted by the description "personal computer" (PC) which describes the fact that it has been designed to be used by one person at a time, unlike mainframes and minicomputers.
[edit] Description
Most of the equipment used by a microcomputer is tightly integrated within a single case, although some equipment may be connected at short distances outside the case, such as monitors, keyboards, mice, etc. Generally, a microcomputer cannot be very big, due to the fact that it should be able to fit well on desks or tables. Bigger computers like minicomputers, mainframes, and supercomputers would take up a much larger portion of a large cabinet or even an entire room.
Most microcomputers serve only a single user at a time. However, some can serve in the form of PCs and workstations running e.g. a UNIX(-like) operating system, may cater to several users concurrently.
A microcomputer comes equipped with at least one type of data storage, a high-speed, volatile device known as RAM, and a CPU. Although some microcomputers (particularly early 8-bit home micros) can perform simple tasks using RAM alone, some form of secondary storage is normally desirable. In the early days of home micros, this may have been something as simple as a cassette deck (in many cases as an external unit). Later, there was a tendency for secondary storage (particularly in the form of floppy and hard disk drives) to be built in to the microcomputer case itself.
Other devices that make up a complete microcomputer system can include its power supply, and various input/output devices used to convey information to and from a human operator (printers, monitors, human interface devices).
[edit] History
The world's first commercial microprocessor was the Intel 4004, released on November 15, 1971. The 4004 processed 4 binary digits (bits) of data in parallel; in other words, it was a 4-bit processor. At the turn of the century 30 years later, microcomputers in embedded systems (built into home appliances, vehicles, and all sorts of equipment) most often are 8-bit, 16-bit, 32-bit, or 64-bit. Desktop/consumer microcomputers, like Apple Macintosh and PCs, are predominantly 32-bit but increasingly 64-bit, while most science and engineering workstations and supercomputers as well as database and financial transaction servers are 64-bit (with one or more CPUs).
The Datapoint 2200, made by CTC in 1970, is perhaps the best candidate for the title of "first microcomputer". While it contains no microprocessor, its custom TTL logic was the basis for the Intel 8008, and for practical purposes the system behaves approximately as if it contains an 8008.
Another early system, the Kenbak-1, 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.[1]. Another system of note is the Micral-N, 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 8800 (1975) was arguably the most famous. Most of these simple, early microcomputers were sold as kits--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. The MITS Altair 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 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.
1977 saw the introduction of the second generation, known as home computers. 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 minicomputers, which many hobbyists and early manufactures were familiar with.
1977 also saw the launch of the VisiCalc spreadsheet (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 PC, the term Personal Computer became generally used for microcomputers compatible with the IBM PC architecture (PC compatible).
[edit] References and footnotes
- ^ Proof of "micro" as a once-common term:
(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 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. - ^ As neither term is precisely-defined, the degree of overlap is debatable. An early use of the term "personal computer" in 1962 predates microprocessor-based designs. (See "Personal Computer: Computers at Home" reference below). Similarly, "microcomputer" may technically encompass applications beyond "personal computers". Additional complications include whether "personal computer" is being used generically or to denote an IBM PC compatible machine.
- ^ "Personal Computer: Computers at Home", Wikipedia article section. Version used dated 2006-11-04, retrieved 2006-11-07.
