# Classes of computers
Computer systems are sorted into classes along three standard lines: size and computing power, which yields the supercomputer, mainframe, minicomputer, microcomputer, and embedded computer; the kind of data processed, which distinguishes analog, digital, and hybrid machines; and intended use, which separates general-purpose from special-purpose designs.[1](https://engineeringhulk.com/classification-of-computer/) The boundaries between classes are set by intended use and price rather than by any single technical threshold, and the classes themselves have shifted as hardware costs have fallen.
| Key fact | Detail |
|---|---|
| Standard size classes | Supercomputer, mainframe, minicomputer (now midrange), microcomputer, and embedded computer[1](https://engineeringhulk.com/classification-of-computer/) |
| Origin of "mainframe" | The term probably derives from the "main frame" of telephone switches, the frames holding processor circuits and main memory, and came to mean big computer[2](https://www.computerhistory.org/brochures/mainframes/) |
| First quintessential mini | The DEC PDP-8, produced in 1964 starting at $16,000, when most computers cost between $100,000 and $1,000,000[3](https://www.computerhistory.org/brochures/minicomputers/) |
| Modern personal computer | Basically the design revealed with the 1981 IBM PC, a microprocessor-based machine with its own memory, storage, and I/O[4](https://www.computerhistory.org/brochures/personal/) |
| Supercomputer ranking | The TOP500 project, launched in 1993, ranks systems by the Linpack benchmark, solving a dense set of linear equations \( A \cdot x = b \)[5](https://www.top500.org/project/) |
| Mainframe versus supercomputer | A mainframe runs a huge number of small, real-time transactions simultaneously; a supercomputer works on fewer, far larger computational problems, executing quadrillions or even quintillions of floating-point calculations per second[6](https://www.ibm.com/think/topics/mainframe/jcr%3Acontent) |
| Embedded computer | A computer system that is an integral part of a larger system, per the CNSSI 4009-2015 definition[7](https://csrc.nist.rip/glossary/term/embedded_computer) |
| Cloud computing | Defined by NIST SP 800-145 as on-demand network access to a shared pool of configurable computing resources, with five essential characteristics, three service models, and four deployment models[8](https://csrc.nist.gov/pubs/sp/800/145/final) |
## Classification schemes
Three classification axes appear repeatedly in the literature. By size and power, the sequence runs from supercomputer down through mainframe, minicomputer, and microcomputer to the embedded computer.[1](https://engineeringhulk.com/classification-of-computer/) By data handled, systems are analog, digital, or hybrid. By purpose, a machine is general-purpose or special-purpose, built for one task.[1](https://engineeringhulk.com/classification-of-computer/)
The size taxonomy was formalized early. In 1971 [Gordon Bell](https://www.edgepedia.org/gordon-bell), then at minicomputer-maker DEC, and [Allen Newell](https://www.edgepedia.org/allen-newell), a professor at Carnegie-Mellon University, published *Computer Structures*, a landmark book that established a taxonomy of computers and documented the important historical systems.[9](https://computerhistory.org/blog/computer-history-museum-celebrating-35-years/) Market-research definitions later made the classes operational: Dataquest's 1998 semiconductor market definitions specified, for example, that a mainframe is a general-purpose information system with a starting price above $100,000, typically 64-bit CPUs, full-time professional support staff, and more than 100 concurrent users.[10](https://archive.computerhistory.org/resources/access/text/2013/04/102723356-05-01-acc.pdf)
## Supercomputers
Supercomputers are large machines designed for problems whose solution is limited by the number of calculations involved, such as weather prediction, simulation of explosions, and drug design.[11](https://www.computerhistory.org/brochures/thm-42b97ff722236/) [Seymour Cray](https://www.edgepedia.org/seymour-cray), the field's defining designer, first built such machines for [Control Data Corporation](https://www.edgepedia.org/control-data-corporation) and later for his own firms; his CRAY-1, introduced in 1976, became the icon of the supercomputer world with its distinctive rounded design.[11](https://www.computerhistory.org/brochures/thm-42b97ff722236/)
Because "supercomputer" is a moving target, the field relies on a benchmark rather than a definition. The TOP500 project, launched in 1993, does not define the term as such; it ranks systems by their ability to solve a set of linear equations \( A \cdot x = b \) using a dense random matrix in floating-point arithmetic, and any architecture that can do so qualifies for the list.[5](https://www.top500.org/project/) The project itself notes that the rank reflects only linear-equation performance and says nothing about other applications.[5](https://www.top500.org/project/) Contemporary systems illustrate the scale: NASA's Athena supercomputer, announced in January 2026 at the [Ames Research Center](https://www.edgepedia.org/ames-research-center), delivers over 20 petaflops of peak performance and surpasses its predecessors Aitken and Pleiades in power and efficiency.[12](https://www.nasa.gov/technology/computing/nasa-launches-its-most-powerful-efficient-supercomputer/) A newer hybrid category, the quantum-centric supercomputer, couples a quantum computer with a classical supercomputer through co-designed infrastructure, middleware, and applications.[13](https://www.ibm.com/think/topics/quantum-centric-supercomputing)
## Mainframes
A mainframe is a large, high-performance computer designed for continuous operation and high-volume transaction processing.[6](https://www.ibm.com/think/topics/mainframe/jcr%3Acontent) Although the label is not precisely defined, it generally denotes a computer suited to large-scale workloads that require high availability, high I/O rates, substantial storage for online databases, and occasionally the capacity to operate several operating systems at the same time.[2](https://www.computerhistory.org/brochures/mainframes/) The term probably derives from the "main frame", the frames designed for telephone switches that held processor circuits and main memory, separate from the cabinets holding other components; over time "main frame" became "mainframe" and came to mean big computer.[14](https://www.computerhistory.org/revolution/story/166)
**Workloads define the class.** Most mainframe workloads fall into two categories: batch processing, in which a job reads and processes data in bulk without user interaction (a z/OS batch job might process millions of records), and online transaction processing, which occurs interactively with the end user and must support an unpredictable number of concurrent users.[15](https://www.ibm.com/docs/en/zos-basic-skills?topic=today-mainframe-workloads-batch-online-transaction-processing) IBM contrasts the mainframe with the commodity server, which handles a specific task such as file hosting, web hosting, or running a database for a defined set of users: a mainframe consolidates that work onto one machine, handling massive transaction volumes and heavy continuous use without the performance drop a server sees under load, due to its high-bandwidth I/O and workload management.[6](https://www.ibm.com/think/topics/mainframe/jcr%3Acontent) Mainframes remain the transactional backbone for banking, insurance, and government industries running high-volume, always-on processing.[6](https://www.ibm.com/think/topics/mainframe/jcr%3Acontent)
## Minicomputers
The term "minicomputer" typically refers to the small, low-cost machines designed for laboratory use that first appeared during the 1960s and early 1970s; the DEC PDP-8, launched in 1964 at a starting price of $16,000, is widely regarded as the original and archetypal mini.[3](https://www.computerhistory.org/brochures/minicomputers/) A minicomputer is a simple, fast, inexpensive machine easily connected to other equipment that responds quickly to outside signals; at first called "real-time control computers", they were later dubbed minicomputers as their applications broadened beyond real-time control.[16](https://www.computerhistory.org/revolution/minicomputers/11/332) At one point more than 100 companies made minis, and most failed to survive the competition, with a few lasting until personal computers made minis obsolete.[16](https://www.computerhistory.org/revolution/minicomputers/11/332)
Two early machines mark the class's origins. Seymour Cray designed the CDC 160, a simple $60,000 computer that offloaded input/output tasks from CDC's $1,000,000 CDC 1604, demonstrating to future minicomputer designers how to build a fast, effective, low-cost machine; the modified 160A sold more than 400 units.[17](https://www.computerhistory.org/revolution/story/333) Computer Control Company's DDP-116 was the world's first 16-bit minicomputer, with 172 shipped, and its successors, the IC-based 416 and 516, sold more than 750 machines.[18](https://www.computerhistory.org/revolution/minicomputers/11/336)
## Microcomputers and personal computers
Machines for a single user existed earlier, including the Librascope LGP-30 (1956) and the Bendix G-15 (1956), and minicomputers such as the PDP-1 (1961) and PDP-8 (1964) provided real-time, interactive programming environments; but the personal computer as known today is basically the design revealed with the 1981 IBM PC, a microprocessor-based machine with its own memory, storage, and I/O.[4](https://www.computerhistory.org/brochures/personal/) IBM's first personal computer, "Acorn", was released in 1981 at a price of $1,565.[19](https://www.livescience.com/20718-computer-history.html) The title of first personal computer using a microprocessor went to the 1973 Micral.[20](https://www.computerhistory.org/revolution/personal-computers/17/297)
Because a smartphone functions as a general-purpose digital computer built around a microprocessor and designed for one user at a time, it belongs to the microcomputer category together with tablets and laptops.[1](https://engineeringhulk.com/classification-of-computer/) A related professional category, the workstation, is a single-user system engineered for compute-intensive tasks such as 3D design, video editing, data analysis, and AI workloads, with professional-grade graphics and software certifications that standard PCs lack.[21](https://www.hp.com/us-en/workstations/desktop-workstation-pc.html)
## Servers, clients, and cloud
Networking blurred the size classes into functional roles. In the client/server model, a client is the source of an external request and the server is the program that services it; the model can run between programs on a single computer but typically refers to a network.[22](https://www.ibm.com/docs/en/cics-ts/6.x?topic=interfaces-clientserver-model) In client/server architecture, servers can be microcomputers, minicomputers, or mainframes, so the same physical machine may occupy different classes depending on its role.[23](https://www.ibm.com/docs/en/tcamfma/6.3.0?topic=tepug-glossary-1)
[Cloud computing](https://www.edgepedia.org/cloud-computing) added a procurement dimension to the classification. NIST SP 800-145 characterizes cloud computing as an approach that gives users everywhere easy, on-demand access over the network to a common collection of configurable computing resources—networks, servers, storage, applications, and services—which can be quickly allocated and withdrawn with little management work; this model includes five essential characteristics, three service models, and four deployment models.[8](https://csrc.nist.gov/pubs/sp/800/145/final) A cloud server runs on remotely hosted provider infrastructure that can be scaled as needed and billed according to use, while a mainframe runs on hardware an organization owns and runs itself.[6](https://www.ibm.com/think/topics/mainframe/jcr%3Acontent)
## Embedded computers
An embedded computer is a computer system that is an integral part of a larger system, according to the definition carried in the CNSSI 4009-2015 glossary.[7](https://csrc.nist.rip/glossary/term/embedded_computer) The class is defined by integration rather than by size or speed: the embedded computer serves a particular function within a larger system, such as the dozens of embedded microcomputers in a modern vehicle, dedicated to functions like automatic braking, ignition systems, engine functions, lighting controls, fuel delivery, and on-board diagnostics, wired together by a Control Area Network (CAN) bus.[24](https://csrc.nist.gov/files/pubs/ir/7628/r1/final/docs/draft_nistir_7628_r1_vol2.pdf)
## How classes change
The classes are historical artifacts of falling cost per computation, and each generation's supercomputer tends to become a later generation's ordinary machine. Meanwhile the functional labels, server, client, embedded, and cloud, have proven more durable than the size labels, because they describe what a machine does rather than how large it is.
## References
1. [Classification of Computers: By Size, Data and Purpose, Engineering Hulk](https://engineeringhulk.com/classification-of-computer/)
2. [Mainframes, Selling the Computer Revolution, Computer History Museum](https://www.computerhistory.org/brochures/mainframes/)
3. [Minicomputers, Selling the Computer Revolution, Computer History Museum](https://www.computerhistory.org/brochures/minicomputers/)
4. [Personal, Selling the Computer Revolution, Computer History Museum](https://www.computerhistory.org/brochures/personal/)
5. [About the TOP500 project](https://www.top500.org/project/)
6. [What Is a Mainframe?, IBM](https://www.ibm.com/think/topics/mainframe/jcr%3Acontent)
7. [Embedded computer, NIST CSRC Glossary (CNSSI 4009-2015)](https://csrc.nist.rip/glossary/term/embedded_computer)
8. [SP 800-145, The NIST Definition of Cloud Computing](https://csrc.nist.gov/pubs/sp/800/145/final)
9. [Computer History Museum: Celebrating 35 Years, by Leonard J. Shustek](https://computerhistory.org/blog/computer-history-museum-celebrating-35-years/)
10. [Communications semiconductors and applications worldwide, 1998, Dataquest definitions, Computer History Museum archive](https://archive.computerhistory.org/resources/access/text/2013/04/102723356-05-01-acc.pdf)
11. [Supercomputers, Selling the Computer Revolution, Computer History Museum](https://www.computerhistory.org/brochures/thm-42b97ff722236/)
12. [NASA Launches Its Most Powerful, Efficient Supercomputer, NASA](https://www.nasa.gov/technology/computing/nasa-launches-its-most-powerful-efficient-supercomputer/)
13. [What is Quantum-Centric Supercomputing?, IBM](https://www.ibm.com/think/topics/quantum-centric-supercomputing)
14. [The First Mainframes, CHM Revolution, Computer History Museum](https://www.computerhistory.org/revolution/story/166)
15. [Mainframe workloads: Batch and online transaction processing, IBM](https://www.ibm.com/docs/en/zos-basic-skills?topic=today-mainframe-workloads-batch-online-transaction-processing)
16. [Smaller is Better, CHM Revolution, Computer History Museum](https://www.computerhistory.org/revolution/minicomputers/11/332)
17. [The Birth of the Minicomputer?, CHM Revolution, Computer History Museum](https://www.computerhistory.org/revolution/story/333)
18. [The Price is Right, CHM Revolution, Computer History Museum](https://www.computerhistory.org/revolution/minicomputers/11/336)
19. [History of computers: Timeline of key events and technological breakthroughs, Live Science](https://www.livescience.com/20718-computer-history.html)
20. [What Was The First PC?, CHM Revolution, Computer History Museum](https://www.computerhistory.org/revolution/personal-computers/17/297)
21. [HP Z Workstation desktops, HP](https://www.hp.com/us-en/workstations/desktop-workstation-pc.html)
22. [The client/server model, IBM CICS documentation](https://www.ibm.com/docs/en/cics-ts/6.x?topic=interfaces-clientserver-model)
23. [Glossary, IBM Tivoli documentation](https://www.ibm.com/docs/en/tcamfma/6.3.0?topic=tepug-glossary-1)
24. [DRAFT NISTIR 7628 Revision 1, Guidelines for Smart Grid Cybersecurity, Volume 2, NIST](https://csrc.nist.gov/files/pubs/ir/7628/r1/final/docs/draft_nistir_7628_r1_vol2.pdf)
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*Topic: Encyclopedia › Technology and the built world › Computing and digital systems › Computer hardware*
*Initially written Sep 17, 2026 · Reviewed: Sep 30, 2026; Oct 15, 2026 · Edited: Oct 15, 2026; Oct 25, 2026 · Last review: Oct 15, 2026*
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