Classes of computers: Difference between revisions

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{{Short description|none}}

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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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|style="text-align: left;"|'''Notes:'''

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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;,Microcomputer;,c0 |access-date=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.

* Rackmount computers – The cases of these computers fit into [[19-inch rack]]s, and maybe 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.

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

* [[Laptop|Laptop Computer]]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 [[Palmtoppalmtop 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 Centurycentury, 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. The contemporaryThis term forhas minicomputerfallen isinto [[midrangedisuse.<ref>{{Cite computer]],web such|title=Google asBooks theNgram higher-endViewer [[SPARC]]|url=https://books.google.com/ngrams/graph?content=Minicomputer&year_start=1800&year_end=2019&corpus=26&smoothing=3&direct_url=t1;,Minicomputer;,c0 [[IBM POWER microprocessors|POWER]] and [[Itanium]]access-based systems from [[Oracle Corporation]], [[IBM]] and [[Hewlettdate=2023-Packard]],11-10 and|website=books.google.com the size is now typically smaller, such as a [[tower case]].|language=en}}</ref>

===Mainframe computers===

The term [[mainframe computer]] was created to distinguish the traditional, large, institutional computer intended to service multiple users from the smaller, single-user machines. These computers are capable of handling and processing very large amounts of data quickly. Mainframe computers are used in large institutions such as government, banks, and large corporations.

They are measured in [[Instructions per second#Million instructions per second|MIPS]] (million instructions per second) and can respond to hundreds of millions of users at a time{{Citation needed|date=September 2022}}.

===Supercomputers===

A [[Supercomputersupercomputer]] is focused on performing tasks involving intense numerical calculations such as weather forecasting, fluid dynamics, nuclear simulations, theoretical astrophysics, and complex scientific computations. A supercomputer is a computer that is at the front-line of current processing capacity, particularly speed of calculation. The term supercomputer itself is rather fluid, and the speed of today's supercomputers tends to become typical of tomorrow's ordinary computer. Supercomputer processing speeds are measured in floating-point operations per second, or [[FLOPS]]. An example of a floating-point operation is the calculation of mathematical equations in real numbers. In terms of computational capability, memory size and speed, I/O technology, and topological issues such as bandwidth and latency, supercomputers are the most powerful, are very expensive, and not cost-effective just to perform batch or transaction processing. These computers were developed in 1970s and are the fastest and the highest capacity computers

==Classes by function==

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[[computer server|Server]] usually refers to a computer that is dedicated to providing one or more services. A server is expected to be reliable (e.g. error-correction of RAM; redundant cooling; self-monitoring, RAID), fit for running for several years, and giving useful diagnosis in case of an error. For even increased security, the server may be mirrored. Many smaller servers are actually personal computers that have been dedicated to provide services for other computers.

* A [[database server]] is a server which uses a [[database application]] that provides [[database]] services to other computer programs or to [[Computer|computerscomputer]]s. [[Database|Database management systems]] (DBMSs) frequently provide database-server functionality, and some database management systems (such as [[MySQL]]) rely exclusively on the [[client–server model]] for database access while others (such as [[SQLite]]) are meant for using as an [[embedded database]]. Users access a database server either through a "[[Front and back ends|front end]]" running on the user's computer – which displays requested data – or through the "[[Front and back ends|back end]]", which runs on the server and handles tasks such as data analysis and storage.

* A [[file server]] does not normally perform computational tasks or run programs on behalf of its client workstations but manage and store a large collection of [[computer file]]s. The crucial function of a file server is storage. File servers are commonly found in schools and offices, where users use a [[local area network]] to connect their client computers and use [[Network-attached storage|Network-attached storage (NAS)]] systems to provide data access.

* A [[web server]] is a server that can satisfy [[Client (computing)|client]] requests on the [[World Wide Web]]. A web server can, in general, contain one or more [[Website|websiteswebsite]]s. A web server processes incoming [[Computer network|network]] requests over [[Hypertext Transfer Protocol|HTTP]] and several other related [[Communication protocol|protocols]]. The primary function of a web server is to store, process and deliver [[Webweb page|web pages]]s to clients. The communication between client and server takes place using the [[Hypertext Transfer Protocol|Hypertext Transfer Protocol (HTTP)]]. Pages delivered are most frequently [[HTML|HTML documents]], which may include [[Image|imagesimage]]s, [[Style sheet (web development)|style sheets]] and [[JavaScript|scripts]] in addition to the text content.

* A [[terminal server]] enables organizations to connect devices with an [[RS-232]], [[EIA-422|RS-422]] or [[EIA-485|RS-485]] serial interface to a [[local area network]] (LAN). Products marketed as terminal servers can be very simple devices that do not offer any security functionality, such as [[data encryption]] and user authentication. These provide GUI sessions that can be used by client PCs that work someway like a remote control. Only the screen (and audio) output is shown on the client. The GUI applications run on the server, data (like in files) would be stored in the same LAN, thus avoiding problems, should a client PC be damaged or stolen.

A server may run several [[Virtualvirtual machine|virtual machines]]s (VMs) for different activities, supplying the same environment to each VM as if it ran on dedicated hardware. Different operating systems (OS) can therefore be run at the same time. This technology approach needs special hardware support to be useful and was first the ___domain of mainframes and other large computers. Nowadays, most personal computers are equipped for this task, but for long-term operation or critical systems, specialized server hardware may be needed.<br />

Another approach is to implement VMs on the operating system level, so all VMs run on the same OS instance (or incarnation), but are fundamentally separated to not interfere with each other.

===Workstations===

[[Workstation]]s are computers that are intended to serve one user and may contain special hardware enhancements not found on a personal computer. <!-- (These statements ignore the application of workstations to distributed process control systems and specialized functions such as video animation. Some workstations were created by extending the function of PCs.) Very few machines today are made in this class. --> By the mid -1990s personal computers reached the processing capabilities of mini computers and workstations. Also, with the release of [[Computer multitasking|multi-tasking]] systems such as [[OS/2]], [[Windows NT]] and [[Linux]], the operating systems of personal computers could do the job of this class of machines. Today, the term is used to describe desktop PCs with high-performance hardware. Such hardware is usually aimed at a professional, rather than enthusiast, market (e.g. dual-processor motherboards, error-correcting memory, professional graphics cards).

===Information appliances===

[[Information appliance]]s are computers specially designed to perform a specific "[[user-friendly]]" function—such as [[text editor|editing text]], [[Media player software|playing music]], [[photography]], [[videography]] etc. The term is most commonly applied to battery-operated [[Mobilemobile device|mobile devices]]s, though there are also [[Wearable technology|wearable devices]].

===Embedded computers===

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[[Public computer]]s are open for public uses, possibly as an [[Interactive kiosk]]. There are many places where one can use them, such as [[Internet café|cybercafes]], schools and libraries.

They are normally [[Firewall (computing)|fire-walled]] and restricted to run only their pre-installed software{{Citation needed|date=September 2022}}. The operating system is difficult to change and/or resides on a file server. For example, "[[thin client]]" machines in educational establishments may be reset to their original state between classes. Public computers are generally not expected to keep an individual's data files.

===Personal computer===

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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-present1971–present): It uses [[Microprocessor|Microprocessors]]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}}