Classes of computers: Difference between revisions

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{{chart top|width=95%|Classes of Computers|collapsed=yes}}

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{{tree chart| | | | | | | |Computer|Computer=Computer}}

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{{tree chart| | | |Analog| |Hybrid| |Digital|Analog=Analog|Hybrid=Hybrid|Digital=Digital}}

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{{tree chart| |Super| |Mainframe| |Mobile| |Mini| |Micro|Super=Super Computers|Mainframe=Mainframe Computers||Mobile=Mobile Computers|Mini=Mini Computers|Micro=Micro Computers}}

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=== Microcomputers (personal computers) ===

[[Microcomputer]]s became the most common type of computer in the late 20th century. The term “microcomputer”"microcomputer" was introduced with the advent of systems based on single-chip [[microprocessor]]s. The best-known{{Citation needed|date=September 2022}} early system was the [[Altair 8800]], introduced in 1975. The term "microcomputer" has practically become an [[anachronism]] as it has fallen into disuse.<ref>{{Cite web |title=Google Books Ngram Viewer |url=https://books.google.com/ngrams/graph?content=Microcomputer&year_start=1800&year_end=2019&corpus=26&smoothing=3&direct_url=t1%3B%2CMicrocomputer%3B%2Cc0;,Microcomputer;,c0 {{bare URL inline|access-date=April 2023-11-10 |website=books.google.com |language=en}}</ref>

These computers include:

* [[Desktop computer]]s – A case put under or on a desk. The display may be optional, depending on use. The case size may vary, depending on the required expansion slots. Very small computers of this kind may be integrated into the monitor.

* Rackmount computers – The cases of these computers fit into [[19-inch rack]]s, and maybemay be space-optimized and very flat. A dedicated display, keyboard, and mouse may not exist, but a [[KVM switch]] or built-in remote control (via LAN or other means) can be used to gain console access. Many [[server (computing)|servers]] are rackmount computers and [[data center]]s may have dozens or hundreds of racks with hundreds or thousands of rackmount computers acting as servers.

* In-car computers ([[carputer]]s) – Built into automobiles, for [[In car entertainment|entertainment]], [[Automotive navigation system|navigation]], etc.

* [[Laptop]]s and [[notebook computer]]s – Portable and all in one case.

* [[Tablet computer]] – Like laptops, but with a [[touch-screen]], entirely replacing the physical keyboard.

* [[Smartphone]]s, [[smartbook]]s, and [[palmtop computer]]s – Small handheld personal computers with limited hardware specifications.

* [[Programmable calculator]] – Like small handhelds, but specialized in mathematical work.

* [[Game console|Video game console]]s – Fixed computers built specifically for entertainment purposes.

* [[Handheld game console]]s – The same as game consoles, but small and portable.

===Minicomputers (mid-range computers)===

[[Minicomputer]]s (colloquially, minis) are a class of multi-user [[computer]]s that lie in the middle range of the computing spectrum, in between the smallest [[mainframe computer]]s and the largest single-user systems ([[microcomputer]]s or [[personal computers]]). The term [[superminicomputer|supermini computer]] or simply supermini was used to distinguish more powerful minicomputers that approached mainframes in capability. Superminis (such as the [[Digital Equipment Corporation|DEC]] [[VAX]] or [[Data General Eclipse MV/8000]]) were usually [[32-bit]] at a time when most minicomputers (such as the [[PDP-11]] or [[Data General Eclipse]] or [[IBM Series/1]]) were [[16-bit]]. These traditional minicomputers in the last few decades of the 20th century, found in small to medium-sized businesses, laboratories and embedded in (for example) hospital [[CAT scanner]]s, often would be [[19-inch rack|rack-mounted]] and connect to one or more [[Computer terminals|terminals]] or [[punched tape|tape]]/[[punched card|card]] readers, like mainframes and unlike most personal computers, but require less space and electrical power than a typical mainframe. This term has fallen into disuse.<ref>{{Cite web |title=Google Books Ngram Viewer |url=https://books.google.com/ngrams/graph?content=Minicomputer&year_start=1800&year_end=2019&corpus=26&smoothing=3&direct_url=t1%3B%2CMinicomputer%3B%2Cc0 {{bare URL;,Minicomputer;,c0 inline|access-date=April 2023-11-10 |website=books.google.com |language=en}}</ref>

===Mainframe computers===

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{{Main|History of computing hardware}}The history of computing hardware is often used to reference the different generations of computing devices:

*First generation computers (1940-1955): It used [[vacuum tube]]s such as the [[List of vacuum tubes#6 volt heater.2Ffilament tubes|6J6]]<ref>{{cite book|last1=Dyson|first1=George|title=Turing's Cathedral - The origins of the Digital Universe|url=https://archive.org/details/turingscathedral0000dyso|url-access=registration|date=2012|publisher=Pantheon Books|___location=New York|isbn=978-0-375-42277-5|page=[https://archive.org/details/turingscathedral0000dyso/page/124 124]|chapter=7}}</ref> or specially designed tubes - or even mechanical arrangements, and were relatively slow, energy-hungry and the [[First generation computer|earliest computer]]s were less flexible in their programmability.

*Second generation computers (1956-1963): It useduses [[Discrete device|discrete]] [[Transistor computer|transistors]], and so werethus smaller and consumedconsumes less power.

*Third generation computers (1964-1970): It used [[Integrated Circuits|Integrated Circuits (ICs)]], the main difference between hardware in computers of the 1960s and today being the density of transistors in each IC (beginning with [[Small Scale Integration]] chips like the [[Transistor-transistor logic]] (TTL) [[7400 series|SN7400]] [[logic gates|gates]] with 20 transistors, through [[Medium Scale Integration]] and [[Large Scale Integration]] to [[Very-large-scale integration|Very-large-scale integration (VLSI)]] with over ten billion transistors in a single silicon-based IC "chip".

*Fourth generation computers(1971–present): It uses [[Microprocessor]]s, as millions of ICs were built onto a single silicon-based chip. Since then form factor of computers reduced, task processing & graphic rendering improved and it became more battery-powered with the advent of personal mobile devices such as laptops, tablets, smartphones etc.

==See also==

* [[Lisp machine]]

*[[List of computer size categories]]

*[[Bell's law of computer classes]]

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==External links==

* {{usurped|1=[https://web.archive.org/web/20130211060637/http://www.byte-notes.com/four-types-computers Four types of Computers]}}

{{Computer sizes}}