Microcomputer
Although there is no rigid definition, a
microcomputer (sometimes shortened to
micro) 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.
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. Such early models were primitive, the earliest microprocessors being little more than general-purpose calculator chips. However, as microprocessor design advanced rapidly from the early 1970s onwards, microcomputers in turn grew faster and cheaper, resulting in an explosion in their popularity.
Whilst 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.
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 a server room) and cheap enough to be owned by an individual (instead of shared within a corporation, or school). 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.
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 and
BBC Micro). 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.
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. In general, a microcomputer will not get much bigger than can be put onto most tables or desks. By contrast, bigger computers like
minicomputers,
mainframes, and
supercomputers may take up some portion of a large
cabinet or even an entire room.
Most microcomputers serve only a single user at a time, but some, in the form of PCs and workstations running e.g. a
UNIX(-like)
operating system, may cater to several users concurrently. The µP does most of the job of calculating on and manipulating data that all computers do.
Along with the CPU, a microcomputer will come equipped with at least one type of data storage, a very high-speed, volatile device known as
RAM. 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).
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
first generation of microcomputers, for engineering development and hobbyist personal use, was launched in the mid-1970s; the
MITS Altair being the most well-known example. 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. It was 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).
*
Personal Computer*
Lists of microcomputers*
Minicomputer*
Mainframe computer*
Supercomputer*
History of computing hardware (1960s-present)
