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<span id="openzim-page-title" class="mw-page-title-main"><span class="mw-page-title-main">Mainframe computer</span></span>

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</style><div role="note" class="hatnote navigation-not-searchable">"Mainframe" redirects here. For other uses, see <a href="Mainframe_(disambiguation)" class="mw-disambig" title="Mainframe (disambiguation)">Mainframe (disambiguation)</a>.</div>

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<p>A <b>mainframe computer</b>, informally called a <b>mainframe</b>, <b>maxicomputer</b>,<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> or <b>big iron</b>,<sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> is a <a href="Computer" title="Computer">computer</a> used primarily by large organizations for critical applications like bulk <a href="Data_processing" title="Data processing">data processing</a> for tasks such as <a href="Census" title="Census">censuses</a>, industry and consumer <a href="Statistics" title="Statistics">statistics</a>, <a href="Enterprise_resource_planning" title="Enterprise resource planning">enterprise resource planning</a>, and large-scale <a href="Transaction_processing" title="Transaction processing">transaction processing</a>. A mainframe computer is large but not as large as a <a href="Supercomputer" title="Supercomputer">supercomputer</a> and has more processing power than some other classes of computers, such as <a href="Minicomputer" title="Minicomputer">minicomputers</a>, <a href="Workstation" title="Workstation">workstations</a>, and <a href="Personal_computer" title="Personal computer">personal computers</a>. Most large-scale computer-system architectures were established in the 1960s, but they continue to evolve. Mainframe computers are often used as <a href="Server_(computing)" title="Server (computing)">servers</a>.

</p><p>The term <i>mainframe</i> was derived from the large cabinet, called a <i>main frame</i>,<sup id="cite_ref-4" class="reference"><a href="#cite_note-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> that housed the <a href="Central_processing_unit" title="Central processing unit">central processing unit</a> and main <a href="Computer_memory" title="Computer memory">memory</a> of early computers.<sup id="cite_ref-5" class="reference"><a href="#cite_note-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-6" class="reference"><a href="#cite_note-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-7" class="reference"><a href="#cite_note-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> Later, the term <i>mainframe</i> was used to distinguish high-end commercial computers from less powerful machines.<sup id="cite_ref-8" class="reference"><a href="#cite_note-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup>

</p>

<div class="mw-heading mw-heading2"><h2 id="Design">Design</h2></div>

<p>Modern mainframe design is characterized less by raw computational speed and more by:

</p>

<ul><li>Redundant internal engineering resulting in high reliability and security</li>

<li>Extensive input-output ("I/O") facilities with the ability to offload to separate engines</li>

<li>Strict <a href="Backward_compatibility" title="Backward compatibility">backward compatibility</a> with older software</li>

<li>High hardware and computational utilization rates through virtualization to support massive <a href="Throughput" class="mw-redirect" title="Throughput">throughput</a></li>

<li><a href="Hot_swapping" title="Hot swapping">Hot swapping</a> of hardware, such as processors and memory</li></ul>

<p>The high stability and reliability of mainframes enable these machines to run uninterrupted for very long periods of time, with <a href="Mean_time_between_failures" title="Mean time between failures">mean time between failures</a> (MTBF) measured in decades.

</p><p>Mainframes have <a href="High_availability" title="High availability">high availability</a>, one of the primary reasons for their longevity, since they are typically used in applications where downtime would be costly or catastrophic. The term <a href="Reliability%2C_availability_and_serviceability" title="Reliability, availability and serviceability">reliability, availability and serviceability</a> (RAS) is a defining characteristic of mainframe computers. Proper planning and implementation are required to realize these features. In addition, mainframes are more secure than other computer types: the <a href="National_Institute_of_Standards_and_Technology" title="National Institute of Standards and Technology">NIST</a> vulnerabilities database, <a href="US-CERT" class="mw-redirect" title="US-CERT">US-CERT</a>, rates traditional mainframes such as <a href="IBM_Z" title="IBM Z">IBM Z</a> (previously called z Systems, System z, and zSeries), <a href="Unisys" title="Unisys">Unisys</a> Dorado, and Unisys Libra as among the most secure, with vulnerabilities in the low single digits, as compared to thousands for <a href="Windows" class="mw-redirect" title="Windows">Windows</a>, <a href="UNIX" class="mw-redirect" title="UNIX">UNIX</a>, and <a href="Linux" title="Linux">Linux</a>.<sup id="cite_ref-9" class="reference"><a href="#cite_note-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> Software upgrades usually require setting up the <a href="Operating_system" title="Operating system">operating system</a> or portions thereof, and are non disruptive only when using <a href="Virtualization" title="Virtualization">virtualizing</a> facilities such as IBM <a href="Z/OS" title="Z/OS">z/OS</a> and <a href="IBM_Parallel_Sysplex" title="IBM Parallel Sysplex">Parallel Sysplex</a>, or Unisys XPCL, which support workload sharing so that one system can take over another's application while it is being refreshed.

</p><p>In the late 1950s, mainframes had only a rudimentary interactive interface (the console) and used sets of <a href="Punched_card" title="Punched card">punched cards</a>, <a href="Punched_tape" title="Punched tape">paper tape</a>, or <a href="Magnetic-tape_data_storage" title="Magnetic-tape data storage">magnetic tape</a> to transfer data and programs. They operated in <a href="Batch_processing" title="Batch processing">batch</a> mode to support <a href="Back_office" title="Back office">back office</a> functions such as payroll and customer billing, most of which were based on repeated tape-based <a href="Merge_sort" title="Merge sort">sorting and merging</a> operations followed by <a href="Line_printer" title="Line printer">line printing</a> to preprinted <a href="Continuous_stationery" title="Continuous stationery">continuous stationery</a>. When interactive user terminals were introduced, they were used almost exclusively for applications (e.g. <a href="Computer_reservations_system" class="mw-redirect" title="Computer reservations system">airline booking</a>) rather than program development. However, in 1961 the first<sup id="cite_ref-10" class="reference"><a href="#cite_note-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> academic, general-purpose timesharing system that supported software development,<sup id="cite_ref-11" class="reference"><a href="#cite_note-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup> <a href="Compatible_Time-Sharing_System" title="Compatible Time-Sharing System">CTSS</a>, was released at <a href="Massachusetts_Institute_of_Technology" title="Massachusetts Institute of Technology">MIT</a> on an <a href="IBM_709" title="IBM 709">IBM 709</a>, later 7090 and 7094.<sup id="cite_ref-50th_12-0" class="reference"><a href="#cite_note-50th-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup> <a href="IBM_2741" title="IBM 2741">Typewriter</a> and <a href="Teletype_Corporation" title="Teletype Corporation">Teletype</a> devices were common control consoles for system operators through the early 1970s, although ultimately supplanted by <a href="Computer_keyboard" title="Computer keyboard">keyboard</a>/<a href="Display_device" title="Display device">display</a> devices.

</p><p>By the early 1970s, many mainframes acquired interactive user terminals<sup id="cite_ref-13" class="reference"><a href="#cite_note-13"><span class="cite-bracket">[</span>NB 1<span class="cite-bracket">]</span></a></sup> operating as <a href="Timesharing" class="mw-redirect" title="Timesharing">timesharing</a> computers, supporting hundreds of users simultaneously along with batch processing. Users gained access through keyboard/typewriter terminals and later character-mode text<sup id="cite_ref-14" class="reference"><a href="#cite_note-14"><span class="cite-bracket">[</span>NB 2<span class="cite-bracket">]</span></a></sup> <a href="Computer_terminal" title="Computer terminal">terminal</a> <a href="Cathode-ray_tube" title="Cathode-ray tube">CRT</a> displays with integral keyboards, or finally from <a href="Personal_computer" title="Personal computer">personal computers</a> equipped with <a href="Terminal_emulation" class="mw-redirect" title="Terminal emulation">terminal emulation</a> software. By the 1980s, many mainframes supported general purpose graphic display terminals, and terminal emulation, but not graphical user interfaces. This form of end-user computing became obsolete in the 1990s due to the advent of personal computers provided with <a href="Graphical_user_interface" title="Graphical user interface">GUIs</a>. After 2000, modern mainframes partially or entirely phased out classic "<a href="Monochrome_monitor" title="Monochrome monitor">green screen</a>" and color display terminal access for end-users in favour of Web-style user interfaces.

</p><p>The infrastructure requirements were drastically reduced during the mid-1990s, when <a href="CMOS" title="CMOS">CMOS</a> mainframe designs replaced the older <a href="Bipolar_junction_transistor" title="Bipolar junction transistor">bipolar</a> technology. IBM claimed that its newer mainframes reduced data center energy costs for power and cooling, and reduced physical space requirements compared to <a href="Server_farm" title="Server farm">server farms</a>.<sup id="cite_ref-15" class="reference"><a href="#cite_note-15"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup>

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<div class="mw-heading mw-heading2"><h2 id="Characteristics">Characteristics</h2></div>

<p>Modern mainframes can run multiple different instances of operating systems at the same time. This technique of <a href="Virtual_machine" title="Virtual machine">virtual machines</a> allows applications to run as if they were on physically distinct computers. In this role, a single mainframe can replace higher-functioning hardware services available to conventional <a href="Server_(computing)" title="Server (computing)">servers</a>. While mainframes pioneered this capability, virtualization is now available on most families of computer systems, though not always to the same degree or level of sophistication.<sup id="cite_ref-16" class="reference"><a href="#cite_note-16"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup>

</p><p>Mainframes can add or <a href="Hot_swap" class="mw-redirect" title="Hot swap">hot swap</a> system capacity without disrupting system function, with specificity and granularity to a level of sophistication not usually available with most server solutions. Modern mainframes, notably the <a href="IBM_Z" title="IBM Z">IBM Z</a> servers, offer two levels of <a href="Hardware_virtualization" title="Hardware virtualization">virtualization</a>: logical partitions (<a href="Logical_partition" title="Logical partition">LPARs</a>, via the <a href="PR/SM" class="mw-redirect" title="PR/SM">PR/SM</a> facility) and virtual machines (via the <a href="Z/VM" title="Z/VM">z/VM</a> operating system). Many mainframe customers run two machines: one in their primary data center and one in their <a href="IT_disaster_recovery" title="IT disaster recovery">backup data center</a>—fully active, partially active, or on standby—in case there is a catastrophe affecting the first building. Test, development, training, and production workload for applications and databases can run on a single machine, except for extremely large demands where the capacity of one machine might be limiting. Such a two-mainframe installation can support continuous business service, avoiding both planned and unplanned outages. In practice, many customers use multiple mainframes linked either by <a href="IBM_Parallel_Sysplex" title="IBM Parallel Sysplex">Parallel Sysplex</a> and shared <a href="Direct-access_storage_device" title="Direct-access storage device">DASD</a> (in IBM's case), or with shared, geographically dispersed storage provided by EMC or Hitachi.

</p><p>Mainframes are designed to handle very high volume input and output (I/O) and emphasize throughput computing. Since the late 1950s,<sup id="cite_ref-17" class="reference"><a href="#cite_note-17"><span class="cite-bracket">[</span>NB 3<span class="cite-bracket">]</span></a></sup> mainframe designs have included subsidiary hardware<sup id="cite_ref-18" class="reference"><a href="#cite_note-18"><span class="cite-bracket">[</span>NB 4<span class="cite-bracket">]</span></a></sup> (called <a href="System/360" class="mw-redirect" title="System/360"><i>channels</i></a> or <a href="CDC_6600#Peripheral_Processors_(PPs)" title="CDC 6600"><i>peripheral processors</i></a>) which manage the I/O devices, leaving the CPU free to deal only with high-speed memory. It is common in mainframe shops to deal with massive <a href="Database" title="Database">databases</a> and files. <a href="Gigabyte" title="Gigabyte">Gigabyte</a> to <a href="Terabyte" class="mw-redirect" title="Terabyte">terabyte</a>-size record files are not unusual.<sup id="cite_ref-19" class="reference"><a href="#cite_note-19"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup> Compared to a typical PC, mainframes commonly have hundreds to thousands of times as much <a href="Computer_storage" class="mw-redirect" title="Computer storage">data storage</a> online,<sup id="cite_ref-20" class="reference"><a href="#cite_note-20"><span class="cite-bracket">[</span>16<span class="cite-bracket">]</span></a></sup> and can access it reasonably quickly. Other server families also offload I/O processing and emphasize throughput computing.

</p><p>Mainframe <a href="Return_on_investment" title="Return on investment">return on investment</a> (ROI), like any other computing platform, is dependent on its ability to scale, support mixed workloads, reduce labor costs, deliver uninterrupted service for critical business applications, and several other risk-adjusted cost factors.

</p><p>Mainframes also have execution integrity characteristics for <a href="Fault_tolerant" class="mw-redirect" title="Fault tolerant">fault tolerant</a> computing. For example, z900, z990, System z9, and System z10 servers effectively execute result-oriented instructions twice, compare results, arbitrate between any differences (through instruction retry and failure isolation), then shift workloads "in flight" to functioning processors, including spares, without any impact to operating systems, applications, or users. This hardware-level feature, also found in HP's <a href="NonStop_(server_computers)" title="NonStop (server computers)">NonStop</a> systems, is known as lock-stepping, because both processors take their "steps" (i.e. instructions) together. Not all applications absolutely need the assured integrity that these systems provide, but many do, such as financial transaction processing.

</p>

<div class="mw-heading mw-heading2"><h2 id="Current_market">Current market</h2></div>

<p><a href="IBM" title="IBM">IBM</a>, with the <a href="IBM_Z" title="IBM Z">IBM Z</a> series, continues to be a major manufacturer in the mainframe market. In 2000, <a href="Hitachi" title="Hitachi">Hitachi</a> co-developed the <a href="ZSeries" class="mw-redirect" title="ZSeries">zSeries</a> z900 with IBM to share expenses, and the latest Hitachi AP10000 models are made by IBM. <a href="Unisys" title="Unisys">Unisys</a> manufactures <a href="Burroughs_large_systems" class="mw-redirect" title="Burroughs large systems">ClearPath Libra</a> mainframes, based on earlier <a href="Burroughs_MCP" title="Burroughs MCP">Burroughs MCP</a> products and ClearPath Dorado mainframes based on <a href="UNIVAC" title="UNIVAC">Sperry Univac</a> <a href="OS_2200" title="OS 2200">OS 1100</a> product lines. <a href="Hewlett_Packard_Enterprise" title="Hewlett Packard Enterprise">Hewlett Packard Enterprise</a> sells its unique <a href="NonStop_(server_computers)" title="NonStop (server computers)">NonStop</a> systems, which it acquired with <a href="Tandem_Computers" title="Tandem Computers">Tandem Computers</a> and which some analysts classify as mainframes. <a href="Groupe_Bull" title="Groupe Bull">Groupe Bull</a>'s <a href="General_Comprehensive_Operating_System" title="General Comprehensive Operating System">GCOS</a>, <a href="Stratus_Technologies" title="Stratus Technologies">Stratus</a> <a href="OpenVOS" class="mw-redirect" title="OpenVOS">OpenVOS</a>, <a href="Fujitsu" title="Fujitsu">Fujitsu</a> (formerly Siemens) <a href="BS2000" title="BS2000">BS2000</a>, and Fujitsu-<a href="ICL_VME" title="ICL VME">ICL VME</a> mainframes are still available in Europe, and Fujitsu (formerly Amdahl) <a href="Amdahl_Corporation" title="Amdahl Corporation">GS21</a> mainframes globally. <a href="NEC" title="NEC">NEC</a> with <a href="Advanced_Comprehensive_Operating_System" title="Advanced Comprehensive Operating System">ACOS</a> and Hitachi with AP10000-<a href="Hitachi_VOS3" class="mw-redirect" title="Hitachi VOS3">VOS3</a><sup id="cite_ref-21" class="reference"><a href="#cite_note-21"><span class="cite-bracket">[</span>17<span class="cite-bracket">]</span></a></sup> still maintain mainframe businesses in the Japanese market.

</p><p>The amount of vendor investment in mainframe development varies with market share. Fujitsu and Hitachi both continue to use custom S/390-compatible processors, as well as other CPUs (including POWER and Xeon) for lower-end systems. Bull uses a mixture of <a href="Itanium" title="Itanium">Itanium</a> and <a href="Xeon" title="Xeon">Xeon</a> processors. NEC uses Xeon processors for its low-end ACOS-2 line, but develops the custom NOAH-6 processor for its high-end ACOS-4 series. IBM also develops custom processors in-house, such as the <a href="IBM_Telum" title="IBM Telum">Telum</a>. Unisys produces code compatible mainframe systems that range from laptops to cabinet-sized mainframes that use homegrown CPUs as well as <a href="Xeon" title="Xeon">Xeon</a> processors. Furthermore, there exists a market for software applications to manage the performance of mainframe implementations. In addition to IBM, significant market competitors include <a href="BMC_Software" title="BMC Software">BMC</a><sup id="cite_ref-22" class="reference"><a href="#cite_note-22"><span class="cite-bracket">[</span>18<span class="cite-bracket">]</span></a></sup> and <a href="Precisely_(company)" title="Precisely (company)">Precisely</a>;<sup id="cite_ref-23" class="reference"><a href="#cite_note-23"><span class="cite-bracket">[</span>19<span class="cite-bracket">]</span></a></sup> former competitors include <a href="Compuware" title="Compuware">Compuware</a><sup id="cite_ref-24" class="reference"><a href="#cite_note-24"><span class="cite-bracket">[</span>20<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-25" class="reference"><a href="#cite_note-25"><span class="cite-bracket">[</span>21<span class="cite-bracket">]</span></a></sup> and <a href="CA_Technologies" title="CA Technologies">CA Technologies</a>.<sup id="cite_ref-26" class="reference"><a href="#cite_note-26"><span class="cite-bracket">[</span>22<span class="cite-bracket">]</span></a></sup>

</p>

<div class="mw-heading mw-heading2"><h2 id="History">History</h2></div>

<div role="note" class="hatnote navigation-not-searchable">See also: <a href="History_of_computing_hardware" title="History of computing hardware">History of computing hardware</a></div>

<p>Several manufacturers and their successors produced mainframe computers from the 1950s until the early 21st century, with gradually decreasing numbers and a gradual transition to simulation on Intel chips rather than proprietary hardware. The US group of manufacturers was first known as "<a href="BUNCH" title="BUNCH">IBM and the Seven Dwarfs</a>":<sup id="cite_ref-27" class="reference"><a href="#cite_note-27"><span class="cite-bracket">[</span>23<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page / location: p.83">: p.83 </span></sup> usually <a href="Burroughs_Corporation" title="Burroughs Corporation">Burroughs</a>, <a href="UNIVAC" title="UNIVAC">UNIVAC</a>, <a href="NCR_Voyix" title="NCR Voyix">NCR</a>, <a href="Control_Data_Corporation" title="Control Data Corporation">Control Data</a>, <a href="Honeywell" title="Honeywell">Honeywell</a>, <a href="General_Electric" title="General Electric">General Electric</a> and <a href="RCA" title="RCA">RCA</a>, although some lists varied. Later, with the departure of General Electric and RCA, it was referred to as IBM and the <a href="BUNCH" title="BUNCH">BUNCH</a>. IBM's dominance grew out of their <a href="IBM_700/7000_series" title="IBM 700/7000 series">700/7000 series</a> and, later, the development of the <a href="IBM_System/360" title="IBM System/360">360</a> series mainframes. The latter architecture has continued to evolve into their current zSeries mainframes which, along with the then Burroughs and Sperry (now <a href="Unisys" title="Unisys">Unisys</a>) <a href="Burroughs_large_systems" class="mw-redirect" title="Burroughs large systems">MCP</a>-based and <a href="OS_2200" title="OS 2200">OS1100</a> mainframes, are among the few mainframe architectures still extant that can trace their roots to this early period. While IBM's zSeries can still run 24-bit System/360 code, the 64-bit <a href="IBM_Z" title="IBM Z">IBM Z</a> CMOS servers have nothing physically in common with the older systems. Notable manufacturers outside the US were <a href="Siemens" title="Siemens">Siemens</a> and <a href="Telefunken" title="Telefunken">Telefunken</a> in <a href="Germany" title="Germany">Germany</a>, <a href="International_Computers_Limited" title="International Computers Limited">ICL</a> in the <a href="United_Kingdom" title="United Kingdom">United Kingdom</a>, <a href="Olivetti" title="Olivetti">Olivetti</a> in Italy, and <a href="Fujitsu" title="Fujitsu">Fujitsu</a>, <a href="Hitachi" title="Hitachi">Hitachi</a>, <a href="Oki_Electric_Industry" title="Oki Electric Industry">Oki</a>, and <a href="NEC" title="NEC">NEC</a> in <a href="Japan" title="Japan">Japan</a>. The <a href="Soviet_Union" title="Soviet Union">Soviet Union</a> and <a href="Warsaw_Pact" title="Warsaw Pact">Warsaw Pact</a> countries manufactured close copies of IBM mainframes during the <a href="Cold_War" title="Cold War">Cold War</a>; the <a href="BESM" title="BESM">BESM</a> series and <a href="Strela_computer" title="Strela computer">Strela</a> are examples of independently designed Soviet computers. <a href="Elwro" title="Elwro">Elwro</a> in Poland was another Eastern Bloc manufacturer, producing the <a href="Odra_(computer)" title="Odra (computer)">ODRA</a>, R-32 and R-34 mainframes.

</p><p>Shrinking demand and tough competition started a <a href="Shakeout" title="Shakeout">shakeout</a> in the market in the early 1970s—RCA sold out to UNIVAC and GE sold its business to Honeywell; between 1986 and 1990 Honeywell was bought out by <a href="Groupe_Bull" title="Groupe Bull">Bull</a>; UNIVAC became a division of <a href="Sperry_Corporation" title="Sperry Corporation">Sperry</a>, which later merged with Burroughs to form <a href="Unisys" title="Unisys">Unisys</a> Corporation in 1986.

</p><p>In 1984 estimated sales of desktop computers ($11.6 billion) exceeded mainframe computers ($11.4 billion) for the first time. IBM received the vast majority of mainframe revenue.<sup id="cite_ref-sanger19840205_28-0" class="reference"><a href="#cite_note-sanger19840205-28"><span class="cite-bracket">[</span>24<span class="cite-bracket">]</span></a></sup> During the 1980s, <a href="Minicomputer" title="Minicomputer">minicomputer</a>-based systems grew more sophisticated and were able to displace the lower end of the mainframes. These computers, sometimes called <i>departmental computers</i>, were typified by the <a href="Digital_Equipment_Corporation" title="Digital Equipment Corporation">Digital Equipment Corporation</a> <a href="VAX" title="VAX">VAX</a> series.

</p><p>In 1991, <a href="AT%26T_Corporation" title="AT&T Corporation">AT&T Corporation</a> briefly owned NCR. During the same period, companies found that servers based on microcomputer designs could be deployed at a fraction of the acquisition price and offer local users much greater control over their own systems given the IT policies and practices at that time. Terminals used for interacting with mainframe systems were gradually replaced by <a href="Personal_computer" title="Personal computer">personal computers</a>. Consequently, demand plummeted and new mainframe installations were restricted mainly to financial services and government. In the early 1990s, there was a rough consensus among industry analysts that the mainframe was a dying market as mainframe platforms were increasingly replaced by personal computer networks. <i><a href="InfoWorld" title="InfoWorld">InfoWorld</a></i><span class="nowrap" style="padding-left:0.1em;">'</span>s Stewart Alsop infamously predicted that the last mainframe would be unplugged in 1996; in 1993, he cited Cheryl Currid, a computer industry analyst as saying that the last mainframe "will stop working on December 31, 1999",<sup id="cite_ref-29" class="reference"><a href="#cite_note-29"><span class="cite-bracket">[</span>25<span class="cite-bracket">]</span></a></sup> a reference to the anticipated <a href="Year_2000_problem" title="Year 2000 problem">Year 2000 problem</a> (Y2K).

</p><p>That trend started to turn around in the late 1990s as corporations found new uses for their existing mainframes and as the price of data networking collapsed in most parts of the world, encouraging trends toward more centralized computing. The growth of <a href="E-business" class="mw-redirect" title="E-business">e-business</a> also dramatically increased the number of back-end transactions processed by mainframe software as well as the size and throughput of databases. Batch processing, such as billing, became even more important (and larger) with the growth of e-business, and mainframes are particularly adept at large-scale batch computing. Another factor currently increasing mainframe use is the development of the <a href="Linux" title="Linux">Linux</a> operating system, which <a href="Linux_on_IBM_Z" title="Linux on IBM Z">arrived on IBM mainframe systems</a> in 1999. Linux allows users to take advantage of <a href="Open_source_software" class="mw-redirect" title="Open source software">open source software</a> combined with mainframe hardware <a href="Reliability%2C_availability_and_serviceability" title="Reliability, availability and serviceability">RAS</a>. Rapid expansion and development in <a href="Emerging_market" title="Emerging market">emerging markets</a>, particularly <a href="People's_Republic_of_China" class="mw-redirect" title="People's Republic of China">People's Republic of China</a>, is also spurring major mainframe investments to solve exceptionally difficult computing problems, e.g. providing unified, extremely high volume online transaction processing databases for 1 billion consumers across multiple industries (banking, insurance, credit reporting, government services, etc.) In late 2000, IBM introduced 64-bit <a href="Z/Architecture" title="Z/Architecture">z/Architecture</a>, acquired numerous software companies such as <a href="Cognos" title="Cognos">Cognos</a> and introduced those software products to the mainframe. IBM's quarterly and annual reports in the 2000s usually reported increasing mainframe revenues and capacity shipments. However, IBM's mainframe hardware business has not been immune to the recent overall downturn in the server hardware market or to model cycle effects. For example, in the 4th quarter of 2009, IBM's <a href="IBM_System_z" class="mw-redirect" title="IBM System z">System z</a> hardware revenues decreased by 27% year over year. But MIPS (millions of instructions per second) shipments increased 4% per year over the past two years.<sup id="cite_ref-30" class="reference"><a href="#cite_note-30"><span class="cite-bracket">[</span>26<span class="cite-bracket">]</span></a></sup> Alsop had himself photographed in 2000, symbolically eating his own words ("death to the mainframe").<sup id="cite_ref-31" class="reference"><a href="#cite_note-31"><span class="cite-bracket">[</span>27<span class="cite-bracket">]</span></a></sup>

</p><p>In 2012, <a href="NASA" title="NASA">NASA</a> powered down its last mainframe, an IBM System z9.<sup id="cite_ref-32" class="reference"><a href="#cite_note-32"><span class="cite-bracket">[</span>28<span class="cite-bracket">]</span></a></sup> However, IBM's successor to the z9, the <a href="IBM_System_z10" title="IBM System z10">z10</a>, led a New York Times reporter to state four years earlier that "mainframe technology—hardware, software and services—remains a large and lucrative business for I.B.M., and mainframes are still the back-office engines behind the world's financial markets and much of global commerce".<sup id="cite_ref-33" class="reference"><a href="#cite_note-33"><span class="cite-bracket">[</span>29<span class="cite-bracket">]</span></a></sup> As of 2010, while mainframe technology represented less than 3% of IBM's revenues, it "continue[d] to play an outsized role in Big Blue's results".<sup id="cite_ref-34" class="reference"><a href="#cite_note-34"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup>

</p><p>IBM has continued to launch new generations of mainframes: the <a href="IBM_z13_(microprocessor)" class="mw-redirect" title="IBM z13 (microprocessor)">IBM z13</a> in 2015,<sup id="cite_ref-35" class="reference"><a href="#cite_note-35"><span class="cite-bracket">[</span>31<span class="cite-bracket">]</span></a></sup> the <a href="IBM_z14_(microprocessor)" class="mw-redirect" title="IBM z14 (microprocessor)">z14</a> in 2017,<sup id="cite_ref-36" class="reference"><a href="#cite_note-36"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-37" class="reference"><a href="#cite_note-37"><span class="cite-bracket">[</span>33<span class="cite-bracket">]</span></a></sup> the <a href="IBM_z15_(microprocessor)" class="mw-redirect" title="IBM z15 (microprocessor)">z15</a> in 2019,<sup id="cite_ref-38" class="reference"><a href="#cite_note-38"><span class="cite-bracket">[</span>34<span class="cite-bracket">]</span></a></sup> and the <a href="IBM_Z#IBM_z16" title="IBM Z">z16</a> in 2022, the latter featuring among other things an "integrated on-chip AI accelerator" and the new <a href="IBM_Telum" title="IBM Telum">Telum microprocessor</a>.<sup id="cite_ref-39" class="reference"><a href="#cite_note-39"><span class="cite-bracket">[</span>35<span class="cite-bracket">]</span></a></sup>

</p>

<div class="mw-heading mw-heading2"><h2 id="Differences_from_supercomputers">Differences from supercomputers</h2></div>

<p>A <a href="Supercomputer" title="Supercomputer">supercomputer</a> is a computer at the leading edge of data processing capability, with respect to calculation speed. Supercomputers are used for scientific and engineering problems (<a href="High-performance_computing" title="High-performance computing">high-performance computing</a>) which crunch numbers and data,<sup id="cite_ref-40" class="reference"><a href="#cite_note-40"><span class="cite-bracket">[</span>36<span class="cite-bracket">]</span></a></sup> while mainframes focus on transaction processing. The differences are:

</p>

<ul><li>Mainframes are built to be reliable for <a href="Transaction_processing" title="Transaction processing">transaction processing</a> (measured by <a href="Transaction_Processing_Performance_Council" title="Transaction Processing Performance Council">TPC</a>-metrics; not used or helpful for most supercomputing applications) as it is commonly understood in the business world: the commercial exchange of goods, services, or money. A typical transaction, as defined by the <a href="Transaction_Processing_Performance_Council" title="Transaction Processing Performance Council">Transaction Processing Performance Council</a>,<sup id="cite_ref-41" class="reference"><a href="#cite_note-41"><span class="cite-bracket">[</span>37<span class="cite-bracket">]</span></a></sup> updates a database system for inventory control (goods), airline reservations (services), or banking (money) by adding a record. A transaction may refer to a set of operations including disk read/writes, operating system calls, or some form of data transfer from one subsystem to another which is not measured by the processing speed of the <a href="CPU" class="mw-redirect" title="CPU">CPU</a>. Transaction processing is not exclusive to mainframes but is also used by microprocessor-based servers and online networks.</li>

<li>Supercomputer performance is measured in <a href="Floating_point" class="mw-redirect" title="Floating point">floating point</a> operations per second (<a href="FLOPS" class="mw-redirect" title="FLOPS">FLOPS</a>)<sup id="cite_ref-42" class="reference"><a href="#cite_note-42"><span class="cite-bracket">[</span>38<span class="cite-bracket">]</span></a></sup> or in <a href="Traversed_edges_per_second" title="Traversed edges per second">traversed edges per second</a> or TEPS,<sup id="cite_ref-43" class="reference"><a href="#cite_note-43"><span class="cite-bracket">[</span>39<span class="cite-bracket">]</span></a></sup> metrics that are not very meaningful for mainframe applications, while mainframes are sometimes measured in millions of instructions per second (<a href="Instructions_per_second" title="Instructions per second">MIPS</a>), although the definition depends on the instruction mix measured.<sup id="cite_ref-44" class="reference"><a href="#cite_note-44"><span class="cite-bracket">[</span>40<span class="cite-bracket">]</span></a></sup> Examples of integer operations measured by MIPS include adding numbers together, checking values or moving data around in memory (while moving information to and from storage, so-called <a href="Input/output" title="Input/output">I/O</a> is most helpful for mainframes; and within memory, only helping indirectly). Floating point operations are mostly addition, subtraction, and multiplication (of <a href="IEEE_754-1985" title="IEEE 754-1985"><i>binary</i> floating point</a> in supercomputers; measured by FLOPS) with enough digits of precision to model continuous phenomena such as weather prediction and nuclear simulations (only recently standardized <a href="Decimal_floating_point" title="Decimal floating point"><i>decimal</i> floating point</a>, not used in supercomputers, are appropriate for <a href="Monetary" class="mw-redirect" title="Monetary">monetary</a> values such as those useful for mainframe applications). In terms of computational speed, supercomputers are more powerful.<sup id="cite_ref-45" class="reference"><a href="#cite_note-45"><span class="cite-bracket">[</span>41<span class="cite-bracket">]</span></a></sup></li></ul>

<p>Mainframes and supercomputers cannot always be clearly distinguished; up until the early 1990s, many supercomputers were based on a mainframe architecture with supercomputing extensions. An example of such a system is the <a href="HITAC_S-3800" class="mw-redirect" title="HITAC S-3800">HITAC S-3800</a>, which was instruction-set compatible with <a href="IBM_System/370" title="IBM System/370">IBM System/370</a> mainframes, and could run the <a href="Hitachi_VOS3" class="mw-redirect" title="Hitachi VOS3">Hitachi VOS3</a> operating system (a fork of <a href="MVS" title="MVS">IBM MVS</a>).<sup id="cite_ref-46" class="reference"><a href="#cite_note-46"><span class="cite-bracket">[</span>42<span class="cite-bracket">]</span></a></sup> The S-3800 therefore can be seen as being both simultaneously a supercomputer and also an IBM-compatible mainframe.

</p><p>In 2007,<sup id="cite_ref-47" class="reference"><a href="#cite_note-47"><span class="cite-bracket">[</span>43<span class="cite-bracket">]</span></a></sup> an amalgamation of the different technologies and architectures for <a href="Supercomputer" title="Supercomputer">supercomputers</a> and mainframes has led to a so-called <a href="Gameframe" title="Gameframe">gameframe</a>.

</p>

<ul><li><a href="Channel_I/O" title="Channel I/O">Channel I/O</a></li>

<li><a href="Cloud_computing" title="Cloud computing">Cloud computing</a></li>

<li><a href="Commodity_computing" title="Commodity computing">Commodity computing</a></li>

<li><a href="Computer_types" class="mw-redirect" title="Computer types">Computer types</a></li>

<li><a href="Failover" title="Failover">Failover</a></li>

<li><a href="Gameframe" title="Gameframe">Gameframe</a></li>

<li><a href="List_of_transistorized_computers" title="List of transistorized computers">List of transistorized computers</a></li>

<li><a href="Master_the_Mainframe_Contest" title="Master the Mainframe Contest">Master the Mainframe Contest</a></li></ul>

<div class="mw-heading mw-heading2"><h2 id="Notes">Notes</h2></div>

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<li id="cite_note-13"><span class="mw-cite-backlink"><b><a href="#cite_ref-13">^</a></b></span> <span class="reference-text">Some had been introduced in the 1960s, but their deployment became more common in the 1970s</span>

</li>

<li id="cite_note-14"><span class="mw-cite-backlink"><b><a href="#cite_ref-14">^</a></b></span> <span class="reference-text">Graphics terminals were available but tended to be restricted to niche applications.</span>

</li>

<li id="cite_note-17"><span class="mw-cite-backlink"><b><a href="#cite_ref-17">^</a></b></span> <span class="reference-text">E.g., the <a href="IBM_709" title="IBM 709">IBM 709</a> had channels in 1958.</span>

</li>

<li id="cite_note-18"><span class="mw-cite-backlink"><b><a href="#cite_ref-18">^</a></b></span> <span class="reference-text">Sometimes computers, sometimes more limited.</span>

</li>

</ol></div></div>

<div class="mw-heading mw-heading2"><h2 id="References">References</h2></div>

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</ol></div></div>

<div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2></div>

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<ul><li><a rel="nofollow" class="external text" href="https://www.ibm.com/systems/z/">IBM z Systems mainframes</a></li>

<li><a rel="nofollow" class="external text" href="https://ibmmainframes.com">IBM Mainframe Resources & Support Forum</a></li>

<li><a rel="nofollow" class="external text" href="https://www.technikum29.de/en/computer/univac9400">Univac 9400</a>, a mainframe from the 1960s, still in use in a German computer museum</li>

<li><a rel="nofollow" class="external text" href="https://web.archive.org/web/20120415175507/http://www.computinghistorymuseum.org/teaching/lectures/pptlectures/9-MainframeComputers.ppt">Lectures in the History of Computing: Mainframes</a> (archived copy from the Internet Archive)</li></ul>

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</style><div id="Mainframe_computers95" style="font-size:114%;margin:0 4em"></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%">Australia</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="SILLIAC" title="SILLIAC">SILLIAC</a> (1956)</li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Israel</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="WEIZAC" title="WEIZAC">WEIZAC</a> (1955)</li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Japan</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="FACOM" title="FACOM">FACOM</a> (1954)</li>

<li><a href="FUJIC" title="FUJIC">FUJIC</a> (1949)</li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Sweden</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<li><a href="TRASK_(computer)" title="TRASK (computer)">TRASK</a> (1964)</li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Soviet Union</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<li><a href="Elbrus_(computer)" title="Elbrus (computer)">Elbrus</a></li>

<li>Electronika SS VLSI</li>

<li>See also: Soviet computer systems</li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">United States</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%"><a href="IAS_machine" title="IAS machine">IAS family</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th id="1950s10" scope="row" class="navbox-group" style="width:1%">1950s</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="ILLIAC" title="ILLIAC">ILLIAC</a> (1952)</li>

<li><a href="AVIDAC" title="AVIDAC">AVIDAC</a> (1953)</li>

<li><a href="JOHNNIAC" title="JOHNNIAC">JOHNNIAC</a> (1953)</li>

<li><a href="ORACLE_(computer)" title="ORACLE (computer)">ORACLE</a> (1953)</li>

<li><a href="ORDVAC" title="ORDVAC">ORDVAC</a> (1952)</li>

<li><a href="WEIZAC" title="WEIZAC">WEIZAC</a> (1955)</li>

<li><a href="SILLIAC" title="SILLIAC">SILLIAC</a> (1956)</li>

<li><a href="MANIAC_I" title="MANIAC I">MANIAC I</a> (1956)</li>

<li><a href="MANIAC_II" title="MANIAC II">MANIAC II</a> (1956)</li>

<li><a href="MISTIC" title="MISTIC">MISTIC</a> (1957)</li>

<li><a href="MUSASINO-1" title="MUSASINO-1">MUSASINO-1</a> (1957)</li>

<li><a href="Cyclone_(computer)" title="Cyclone (computer)">Cyclone</a> (1959)</li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">1960s</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li>FACOM 201 (1960)</li>

<li><a href="TRASK_(computer)" title="TRASK (computer)">TRASK</a> (1964)</li></ul>

</div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="University_of_Illinois_Urbana-Champaign" title="University of Illinois Urbana-Champaign">University of Illinois</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="ORDVAC" title="ORDVAC">ORDVAC</a> (1952)</li>

<li><a href="ILLIAC_I" title="ILLIAC I">ILLIAC I</a> (1952)</li>

<li><a href="ILLIAC_II" title="ILLIAC II">ILLIAC II</a> (1958)</li>

<li><a href="ILLIAC_III" title="ILLIAC III">ILLIAC III</a> (1966)</li>

<li><a href="ILLIAC_IV" title="ILLIAC IV">ILLIAC IV</a> (1965)</li>

<li><a href="ILLIAC#CEDAR" title="ILLIAC">CEDAR</a> (1988)</li>

<li><a href="ILLIAC#ILLIAC_6" title="ILLIAC">ILLIAC 6</a> (2005)</li>

<li><a href="ILLIAC#Trusted_ILLIAC" title="ILLIAC">Trusted ILLIAC</a> (2006)</li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Harvard_University" title="Harvard University">Harvard University</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Harvard_Mark_I" title="Harvard Mark I">Harvard Mark I</a> (1944)</li>

<li><a href="Harvard_Mark_II" title="Harvard Mark II">Harvard Mark II</a> (1947)</li>

<li><a href="Harvard_Mark_III" title="Harvard Mark III">Harvard Mark III</a> (1949)</li>

<li><a href="Harvard_Mark_IV" title="Harvard Mark IV">Harvard Mark IV</a> (1952)</li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">IBM</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><td colspan="2" class="navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"><div class="navbox-styles"></div><div role="navigation" class="navbox" aria-labelledby="IBM_vacuum_tube_computers67" style="padding:3px"><table class="nowraplinks mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><div id="IBM_vacuum_tube_computers67" style="font-size:114%;margin:0 4em">IBM vacuum tube computers</div></th></tr><tr><td colspan="2" class="navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="IBM_305_RAMAC" title="IBM 305 RAMAC">305 RAMAC</a></li>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Semi-Automatic_Ground_Environment" title="Semi-Automatic Ground Environment">SAGE</a></th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

</div></td></tr></tbody></table></div></div></td></tr><tr><td colspan="2" class="navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">Mainframes</div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="University_of_Pennsylvania" title="University of Pennsylvania">University of Pennsylvania</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="ENIAC" title="ENIAC">ENIAC</a> (1945)</li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Eckert%E2%80%93Mauchly_Computer_Corporation" title="Eckert–Mauchly Computer Corporation">EMCC</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="EDVAC" title="EDVAC">EDVAC</a> (1949)</li>

<li><a href="UNIVAC_I" title="UNIVAC I">UNIVAC I</a> (1951)</li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Remington_Rand" title="Remington Rand">Remington</a>–<a href="Sperry_Rand" class="mw-redirect" title="Sperry Rand">Sperry Rand</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="UNIVAC_II" title="UNIVAC II">UNIVAC II</a></li>

<li>See also: <a href="List_of_UNIVAC_products" title="List of UNIVAC products">Computers built 1955–1978</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Raytheon_Technologies" class="mw-redirect" title="Raytheon Technologies">Raytheon</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="RAYDAC" title="RAYDAC">RAYDAC</a> (1953)</li></ul>

</div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">United Kingdom</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Colossus_computer" title="Colossus computer">Colossus computer</a> (1943)</li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Related</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Transistor_computer" title="Transistor computer">Transistor computer</a>

<li><a href="Vacuum-tube_computer" title="Vacuum-tube computer">Vacuum-tube computer</a>

<li><a href="History_of_computing_hardware" title="History of computing hardware">History of computing hardware</a></li>

<li><a href="History_of_computing_hardware_(1960s%E2%80%93present)" title="History of computing hardware (1960s–present)">History of computing hardware (1960s–present)</a></li>

<li><a href="List_of_pioneers_in_computer_science" title="List of pioneers in computer science">List of pioneers in computer science</a></li></ul>

</div></td></tr></tbody></table></div>

<div class="navbox-styles"></div><div role="navigation" class="navbox" aria-labelledby="Computer_sizes_and_classes279" style="padding:3px"><table class="nowraplinks hlist mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><div id="Computer_sizes_and_classes279" style="font-size:114%;margin:0 4em"><a href="List_of_computer_size_categories" title="List of computer size categories">Computer sizes</a> and <a href="Classes_of_computers" title="Classes of computers">classes</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Microcomputer" title="Microcomputer">Micro</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%">Static</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Computer_appliance" title="Computer appliance">Appliances</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Arcade_cabinet" title="Arcade cabinet">Arcade cabinet</a></li>

<li><a href="Diskless_node" title="Diskless node">Diskless node</a></li>

<li><a href="Internet_appliance" title="Internet appliance">Internet appliance</a></li>

<li><a href="Intelligent_terminal" class="mw-redirect" title="Intelligent terminal">Intelligent terminal</a></li>

<li><a href="Interactive_kiosk" title="Interactive kiosk">Interactive kiosk</a></li>

<li><a href="Rich_client" title="Rich client">Rich client</a></li>

<li><a href="Simulator_ride" title="Simulator ride">Simulator</a></li>

<li><a href="Smart_speaker" title="Smart speaker">Smart speaker</a></li>

<li><a href="Smart_TV" title="Smart TV">Smart TV</a></li>

<li><a href="Thin_client" title="Thin client">Thin client</a></li>

<li><a href="Video_game_console" title="Video game console">Video game console</a>

<ul><li><a href="Home_video_game_console" title="Home video game console">Home console</a></li>

<li><a href="Microconsole" title="Microconsole">Microconsole</a></li></ul></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Computers</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%">By use</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Gaming_computer" title="Gaming computer">Gaming</a></li>

<li><a href="Industrial_PC" title="Industrial PC">Industrial</a></li>

<li><a href="Personal_computer" title="Personal computer">Personal</a>

<ul><li><a href="Personal_supercomputer" title="Personal supercomputer">Personal super</a></li></ul></li>

<li><a href="Public_computer" title="Public computer">Public</a></li>

<li><a href="Server_(computing)" title="Server (computing)">Server</a>

<ul><li><a href="Home_server" title="Home server">Home server</a></li></ul></li>

<li><a href="Workstation" title="Workstation">Workstation</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">By size</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Panel_PC" title="Panel PC">Panel</a></li>

<li><a href="Table_computer" title="Table computer">Tabletop</a></li>

<li><a href="Surface_computer" title="Surface computer">Surface</a></li></ul></li>

<li><a href="Desktop_computer" title="Desktop computer">Desktop</a>

<ul><li><a href="Deskside_computer" class="mw-redirect" title="Deskside computer">Deskside</a></li>

<li><a href="Pizza-box_form_factor" title="Pizza-box form factor">Pizza box</a></li>

<li><a href="Computer_tower" title="Computer tower">Tower</a></li></ul></li>

<li><a href="Portable_computer" title="Portable computer">Portable</a></li>

<li><a href="Small_form_factor_PC" title="Small form factor PC">Small form factor</a>

<li><a href="Stick_PC" title="Stick PC">Stick PC</a></li></ul></li>

<ul><li><a href="Blade_server" title="Blade server">Blade server</a></li>

<li><a href="Blade_PC" title="Blade PC">Blade PC</a></li></ul></li></ul>

</div></td></tr></tbody></table><div></div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Mobile_computing" title="Mobile computing">Mobile</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Laptop" title="Laptop">Laptop</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="2-in-1_laptop#2-in-1_convertible" title="2-in-1 laptop">Convertible</a></li></ul></li>

<li><a href="Cloudbook" title="Cloudbook">Cloudbook</a></li>

<li><a href="Mobile_workstation" title="Mobile workstation">Mobile workstation</a></li>

<li><a href="Notebook_computer" title="Notebook computer">Notebook</a></li>

<li><a href="Subnotebook" title="Subnotebook">Subnotebook</a>

<ul><li><a href="Netbook" title="Netbook">Netbook</a></li>

<li><a href="Smartbook" title="Smartbook">Smartbook</a></li></ul></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Tablet_computer" title="Tablet computer">Tablet</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="2-in-1_laptop#2-in-1_detachable" title="2-in-1 laptop">Detachable</a></li>

<li><a href="Phablet" title="Phablet">Phablet</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Mobile_device" title="Mobile device">Handheld</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Electronic_organizer" title="Electronic organizer">Electronic organizer</a></li>

<li><a href="E-reader" title="E-reader">E-reader</a></li>

<li><a href="Handheld_game_console" title="Handheld game console">Handheld game console</a></li>

<li><a href="Handheld_PC" title="Handheld PC">Handheld PC</a></li>

<li><a href="Mobile_data_terminal" title="Mobile data terminal">Mobile data terminal</a></li>

<li><a href="Mobile_phone" title="Mobile phone">Mobile phone</a>

<ul><li><a href="Camera_phone" title="Camera phone">Camera</a></li>

<li><a href="Feature_phone" title="Feature phone">Feature</a></li>

<li><a href="Smartphone" title="Smartphone">Smartphone</a>

<ul><li><a href="Foldable_smartphone" title="Foldable smartphone">Foldable</a></li></ul></li></ul></li>

<li><a href="Palmtop_PC" title="Palmtop PC">Palmtop PC</a></li>

<li><a href="Personal_digital_assistant" title="Personal digital assistant">Personal digital assistant</a></li>

<li><a href="Pocket_computer" title="Pocket computer">Pocket</a></li>

<li><a href="Portable_data_terminal" title="Portable data terminal">Portable data terminal</a></li>

<li><a href="Portable_media_player" title="Portable media player">Portable media player</a></li>

<li><a href="Siftable" title="Siftable">Siftable</a></li>

<li><a href="Ultra-mobile_PC" title="Ultra-mobile PC">Ultra-mobile PC</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Calculator" title="Calculator">Calculator</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Graphing_calculator" title="Graphing calculator">Graphing</a></li>

<li><a href="Programmable_calculator" title="Programmable calculator">Programmable</a></li>

<li><a href="Scientific_calculator" title="Scientific calculator">Scientific</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Wearable_computer" title="Wearable computer">Wearable</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Fitness_tracker" title="Fitness tracker">Fitness tracker</a>

<ul><li><a href="Smart_band" class="mw-redirect" title="Smart band">Smart band</a></li></ul></li>

<li><a href="Watch#Digital" title="Watch">Digital wristwatch</a>

<ul><li><a href="Calculator_watch" title="Calculator watch">Calculator watch</a></li>

<li><a href="Smartwatch" title="Smartwatch">Smartwatch</a></li>

<li><a href="GPS_watch" title="GPS watch">Sportwatch</a></li></ul></li>

<li><a href="Smartglasses" title="Smartglasses">Smartglasses</a></li>

<li><a href="Smart_ring" title="Smart ring">Smart ring</a></li></ul>

<li><a href="Superminicomputer" title="Superminicomputer">Supermini</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Large</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<li><a href="Minisupercomputer" title="Minisupercomputer">Minisuper</a></li>

<li><a href="Supercomputer" title="Supercomputer">Super</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Others</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Embedded_system" title="Embedded system">Embedded system</a></li>

<li><a href="Information_appliance" title="Information appliance">Information appliance</a></li>

<li><a href="Microcontroller" title="Microcontroller">Microcontroller</a></li>

<li><a href="Rugged_computer" title="Rugged computer">Rugged</a>

<ul><li><a href="Rugged_smartphone" title="Rugged smartphone">Rugged smartphone</a></li></ul></li>

<li><a href="Single-board_computer" title="Single-board computer">Single-board</a>

<ul><li><a href="Computer-on-module" title="Computer-on-module">Computer-on-module</a></li></ul></li>

<li><a href="Smartdust" title="Smartdust">Smartdust</a></li>

<li><a href="Wireless_sensor_network" title="Wireless sensor network">Wireless sensor network</a></li></ul>

</div></td></tr><tr><td class="navbox-abovebelow" colspan="2"><div>

<ul><li><span class="noviewer" typeof="mw:File"><span title="Category"></span></span> Category</li></ul>

</div></td></tr></tbody></table></div>

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