A minicomputer, or colloquially mini, is a type of smaller general-purpose computer developed in the mid-1960s[1][2] and sold at a much lower price than mainframe[3] and mid-size computers from IBM and its direct competitors. In a 1970 survey, The New York Times suggested a consensus definition of a minicomputer as a machine costing less than US$25,000 (equivalent to $196,000in 2023[4]), with an input-output device such as a teleprinter and at least four thousand words of memory, that is capable of running programs in a higher level language, such as Fortran or BASIC.[5]
The class formed a distinct group with its own software architectures and operating systems. Minis were designed for control, instrumentation, human interaction, and communication switching as distinct from calculation and record keeping. Many were sold indirectly to original equipment manufacturers (OEMs) for final end-use application. During the two-decade lifetime of the minicomputer class (1965–1985), almost 100 companies formed and only a half dozen remained.[6]
The term "minicomputer" developed in the 1960s[7] to describe the smaller computers that became possible with the use of transistors and core memory technologies, minimal instructions sets and less expensive peripherals such as the ubiquitous Teletype Model 33 ASR.[6][8] They usually took up one or a few 19-inch rack cabinets, compared with the large mainframes that could fill a room.[9]
In terms of relative computing power compared to contemporary mainframes, small systems that were similar to minicomputers had been available from the 1950s. In particular, there was an entire class of drum machines, like the UNIVAC 1101 and LGP-30, that share some features of the minicomputer class. Similar models using magnetic delay-line memory followed in the early 1960s. These machines, however, were essentially designed as small mainframes, using a custom chassis and often supporting only peripherals from the same company. In contrast, the machines that became known as minicomputers were often designed to fit into a standard chassis and deliberately designed to use common devices like the ASR33.
Another common difference was that most earlier small machines were not "general purpose", in that they were designed for a specific role like process control or accounting. On these machines, programming was generally carried out in their custom machine language, or even hard-coded into a plugboard, although some used a form of BASIC.[citation needed][example needed] DEC wrote, regarding their PDP-5, that it was "the world’s first commercially produced minicomputer".[10] It meets most definitions of "mini" in terms of power and size, but was designed and built to be used as an instrumentation system in labs, not as a general-purpose computer.[11] Many similar examples of small special-purpose machines exist from the early 1960s, including the UK Ferranti Argus and Soviet UM-1NKh.
The CDC 160, circa 1960, is sometimes pointed to as an early example of a minicomputer, as it was small, transistorized and (relatively) inexpensive. However, its basic price of $100,000 (equivalent to $1,029,921in 2023) and custom desk-like chassis places it within the "small system" or "midrange computer"[12] category as opposed to the more modern use of the term minicomputer. Nevertheless, it retains a strong contender for the term "first minicomputer".[11]
1960s and 1970s success
Most computing histories point to the 1964 introduction of Digital Equipment Corporation's (DEC) 12-bitPDP-8 as the first minicomputer.[13] Some of this is no doubt due to DEC's widespread use of the term starting in the mid-1960s.[14] Smaller systems, including those from DEC like the PDP-5 and LINC,[15] had existed prior to this point, but it was the PDP-8 combination of small size, general purpose orientation and low price that puts it firmly within the modern definition. Its introductory price of $18,500[16] (equivalent to $178,866in 2023) places it in an entirely different market segment than earlier examples like the CDC 160.
In contemporary terms, the PDP-8 was a runaway success, ultimately selling 50,000 examples.[a] Follow-on versions using small scale integrated circuits further lowered the cost and size of the system. Its success led to widespread imitation, and the creation of an entire industry of minicomputer companies along Massachusetts Route 128, including Data General, Wang Laboratories and Prime Computer. Other popular minis from the era were the HP 2100, Honeywell 316 and TI-990.
Raytheon RDS 500 seismic processing system in Benghazi in 1978Varian Data Machines system connected to analogue tape playback system in 1984
Early minis had a variety of word sizes, with DEC's 12 and 18-bit systems being typical examples. The introduction and standardization of the 7-bit ASCII character set led to the move to 16-bit systems, with the late-1969 Data General Nova being a notable entry in this space. By the early 1970s, most minis were 16-bit, including DEC's PDP-11. For a time, "minicomputer" was almost synonymous with "16-bit", as the larger mainframe machines almost always used 32-bit or larger word sizes.
Raytheon RDS 704 onsite seismic processing system in Mogadishu in 1974
As integrated circuit design improved, especially with the introduction of the 7400-series integrated circuits, minicomputers became smaller, easier to manufacture, and as a result, less expensive. They were used in manufacturing process control, telephone switching and to control laboratory equipment. In the 1970s, they were the hardware that was used to launch the computer-aided design (CAD) industry[17] and other similar industries where a small dedicated system was needed.
The boom in worldwide seismic exploration for oil and gas in the early 1970s saw the widespread use of minicomputers in dedicated processing centres close to the data collection crews. Raytheon Data Systems RDS 704 and later RDS 500 were predominantly the systems of choice for nearly all the geophysical exploration as well as oil companies.[18][19]
At the launch of the MITS Altair 8800 in 1975, Radio Electronics magazine referred to the system as a "minicomputer", although the term microcomputer soon became usual for personal computers based on single-chip microprocessors. At the time, microcomputers were 8-bit single-user, relatively simple machines running simple program-launcher operating systems like CP/M or MS-DOS, while minis were much more powerful systems that ran full multi-user, multitasking operating systems, such as VMS and Unix.
The Tandem Computers NonStop product line shipped its first fully fault-tolerant cluster computer in 1976.[20][21][22]
Around the same time, minis began to move upward in size. Although several 24 and 32-bit minis had entered the market earlier, it was DEC's 1977 VAX, which they referred to as a superminicomputer, or supermini, that caused the mini market to move en-masse to 32-bit architectures. This provided ample headroom even as single-chip 16-bit microprocessors like the TMS 9900 and Zilog Z8000 appeared in the later 1970s. Most mini vendors introduced their own single-chip processors based on their own architecture and used these mostly in low-cost offerings while concentrating on their 32-bit systems. Examples include the Intersil 6100 single-chip PDP-8, DEC T-11 PDP-11, microNOVA and Fairchild 9440 Nova, and TMS9900 TI-990.
Mid-1980s and 1990s decline
By the early 1980s, the 16-bit market had all but disappeared as newer 32-bit microprocessors began to improve in performance. Those customers who required more performance than these offered had generally already moved to 32-bit systems by this time. But it was not long before this market also began to come under threat; the Motorola 68000 offered a significant percentage of the performance of a typical mini in a desktop platform. True 32-bit processors like the National Semiconductor NS32016, Motorola 68020 and Intel 80386 soon followed. By the mid-1980s, high-end microcomputers offered CPU performance equal to low-end and mid-range minis, and the new RISC approach promised performance levels well beyond the fastest minis, and even high-end mainframes.
All that really separated micros from the mini market was storage and memory capacity. Both of these began to be addressed through the later 1980s; 1 MB of RAM became typical by around 1987, desktop hard drives rapidly pushed past the 100 MB range by 1990, and the introduction of inexpensive and easily deployable local area network (LAN) systems provided solutions for those looking for multi-user systems. The introduction of the workstation machines opened new markets for graphics-based systems that the terminal-oriented minis could not even address. Minis retained a force for those using existing software products or those who required high-performance multitasking, but the introduction of newer operating systems based on Unix began to become highly practical replacements for these roles as well. For computational science, clusters of commodity PCs largely replaced minicomputers.
Mini vendors began to rapidly disappear through this period. Data General responded to the changing market by focusing entirely on the high-performance file server market, embracing a role within large LANs that appeared resilient. This did not last; Novell NetWare rapidly pushed such solutions into niche roles, and later versions of Microsoft Windows did the same to Novell. DEC decided to move into the large-computer space instead, introducing the VAX 9000 mainframe in 1989, but it was a flop in the market and disappeared after almost no sales. The company then attempted to enter the workstation and server markets with the DEC Alpha, but was too late to save the company and they eventually sold their remains to Compaq in 1998. By the end of the decade all of the classic vendors were gone; Data General, Prime, Computervision, Honeywell, and Wang, failed, merged, or were bought out.
Today, only a few proprietary minicomputer architectures survive. The IBM System/38 operating system, which introduced many advanced concepts, lives on with IBM's AS/400. Great efforts were made by IBM to enable programs originally written for the IBM System/34 and System/36 to be moved to the AS/400. After being rebranded multiple times, the AS/400 platform was replaced by IBM Power Systems running IBM i. In contrast, competing proprietary computing architectures from the early 1980s, such as DEC's VAX, Wang VS, and Hewlett-Packard's HP 3000 have long been discontinued without a compatible upgrade path. OpenVMS was ported to HP Alpha and Intel IA-64 (Itanium) CPU architectures, and now runs on x86-64 processors.
Tandem Computers, which specialized in reliable large-scale computing, was acquired by Compaq in 1997, and in 2001 the combined entity merged with Hewlett-Packard.[23] The NonStop Kernel-based NonStop product line was re-ported from MIPS processors to Itanium-based processors branded as 'HP Integrity NonStop Servers'. As in the earlier migration from stack machines to MIPS microprocessors, all customer software was carried forward without source changes. Integrity NonStop continues to be HP's answer for the extreme scaling needs of its very largest customers. The NSK operating system, now termed NonStop OS, continues as the base software environment for the NonStop Servers, and has been extended to include support for Java and integration with popular development tools like Visual Studio and Eclipse. Later, Hewlett-Packard would split into HP and Hewlett-Packard Enterprise. The NonStop products and the DEC products would then be sold by HPE.
Several pioneering computer companies first built minicomputers, such as DEC, Data General, and Hewlett-Packard (HP) (who now refers to its HP3000 minicomputers as "servers" rather than "minicomputers"). And although today's PCs and servers are clearly microcomputers physically, architecturally their CPUs and operating systems have developed largely by integrating features from minicomputers.[citation needed]
In the software context, the relatively simple OSs for early microcomputers were usually inspired by minicomputer OSs (such as CP/M's similarity to Digital's single user OS/8 and RT-11 and multi-user RSTS time-sharing system). Also, the multiuser OSs of today are often either inspired by, or directly descended from, minicomputer OSs.[citation needed]UNIX was originally a minicomputer OS, while the Windows NT kernel, the foundation for all current versions of Microsoft Windows, borrowed design ideas liberally from VMS. Many of the first generation of PC programmers were educated on minicomputer systems.[24][25]
↑ For comparison, the CDC 160 sold about 50 units.
Related Research Articles
Digital Equipment Corporation, using the trademark Digital, was a major American company in the computer industry from the 1960s to the 1990s. The company was co-founded by Ken Olsen and Harlan Anderson in 1957. Olsen was president until he was forced to resign in 1992, after the company had gone into precipitous decline.
A mainframe computer, informally called a mainframe or big iron, is a computer used primarily by large organizations for critical applications like bulk data processing for tasks such as censuses, industry and consumer statistics, enterprise resource planning, and large-scale transaction processing. A mainframe computer is large but not as large as a supercomputer and has more processing power than some other classes of computers, such as minicomputers, servers, workstations, and personal computers. Most large-scale computer-system architectures were established in the 1960s, but they continue to evolve. Mainframe computers are often used as servers.
A microcomputer is a small, relatively inexpensive computer having a central processing unit (CPU) made out of a microprocessor. The computer also includes memory and input/output (I/O) circuitry together mounted on a printed circuit board (PCB). Microcomputers became popular in the 1970s and 1980s with the advent of increasingly powerful microprocessors. The predecessors to these computers, mainframes and minicomputers, were comparatively much larger and more expensive. Many microcomputers are also personal computers. An early use of the term "personal computer" in 1962 predates microprocessor-based designs. (See "Personal Computer: Computers at Companies" reference below). A "microcomputer" used as an embedded control system may have no human-readable input and output devices. "Personal computer" may be used generically or may denote an IBM PC compatible machine.
A workstation is a special computer designed for technical or scientific applications. Intended primarily to be used by a single user, they are commonly connected to a local area network and run multi-user operating systems. The term workstation has been used loosely to refer to everything from a mainframe computer terminal to a PC connected to a network, but the most common form refers to the class of hardware offered by several current and defunct companies such as Sun Microsystems, Silicon Graphics, Apollo Computer, DEC, HP, NeXT, and IBM which powered the 3D computer graphics revolution of the late 1990s.
Data General Corporation was one of the first minicomputer firms of the late 1960s. Three of the four founders were former employees of Digital Equipment Corporation (DEC).
A superminicomputer, colloquially supermini, is a high-end minicomputer. The term is used to distinguish the emerging 32-bit architecture midrange computers introduced in the mid to late 1970s from the classical 16-bit systems that preceded them. The development of these computers was driven by the need of applications to address larger memory. The term midicomputer had been used earlier to refer to these systems. Virtual memory was often an additional criteria that was considered for inclusion in this class of system. The computational speed of these machines was significantly greater than the 16-bit minicomputers and approached the performance of small mainframe computers. The name has at times been described as a "frivolous" term created by "marketeers" that lacks a specific definition. Describing a class of system has historically been seen as problematic: "In the computer kingdom, taxonomic classification of equipment is more of a black art than a science." There is some disagreement about which systems should be included in this class. The origin of the name is uncertain.
Tandem Computers, Inc. was the dominant manufacturer of fault-tolerant computer systems for ATM networks, banks, stock exchanges, telephone switching centers, 911 systems, and other similar commercial transaction processing applications requiring maximum uptime and no data loss. The company was founded by Jimmy Treybig in 1974 in Cupertino, California. It remained independent until 1997, when it became a server division within Compaq. It is now a server division within Hewlett Packard Enterprise, following Hewlett-Packard's acquisition of Compaq and the split of Hewlett-Packard into HP Inc. and Hewlett Packard Enterprise.
The history of computing hardware starting at 1960 is marked by the conversion from vacuum tube to solid-state devices such as transistors and then integrated circuit (IC) chips. Around 1953 to 1959, discrete transistors started being considered sufficiently reliable and economical that they made further vacuum tube computers uncompetitive. Metal–oxide–semiconductor (MOS) large-scale integration (LSI) technology subsequently led to the development of semiconductor memory in the mid-to-late 1960s and then the microprocessor in the early 1970s. This led to primary computer memory moving away from magnetic-core memory devices to solid-state static and dynamic semiconductor memory, which greatly reduced the cost, size, and power consumption of computers. These advances led to the miniaturized personal computer (PC) in the 1970s, starting with home computers and desktop computers, followed by laptops and then mobile computers over the next several decades.
The HP 2100 is a series of 16-bit minicomputers that were produced by Hewlett-Packard (HP) from the mid-1960s to early 1990s. Tens of thousands of machines in the series were sold over its twenty-five year lifetime, making HP the fourth largest minicomputer vendor during the 1970s.
The HP 3000 series is a family of 16-bit and 32-bit minicomputers from Hewlett-Packard. It was designed to be the first minicomputer with full support for time-sharing in the hardware and the operating system, features that had mostly been limited to mainframes, or retrofitted to existing systems like Digital's PDP-11, on which Unix was implemented. First introduced in 1972, the last models reached end-of-life in 2010, making it among the longest-lived machines of its generation.
Minisupercomputers constituted a short-lived class of computers that emerged in the mid-1980s, characterized by the combination of vector processing and small-scale multiprocessing. As scientific computing using vector processors became more popular, the need for lower-cost systems that might be used at the departmental level instead of the corporate level created an opportunity for new computer vendors to enter the market. As a generalization, the price targets for these smaller computers were one-tenth of the larger supercomputers.
Commodity computing involves the use of large numbers of already-available computing components for parallel computing, to get the greatest amount of useful computation at low cost. This is a useful alternative to high-cost superminicomputers or boutique computers. Commodity computers are computer systems - manufactured by multiple vendors - incorporating components based on open standards.
The BUNCH was the nickname for the group of mainframe computer competitors of IBM in the 1970s. The name is derived from the names of the five companies: Burroughs, UNIVAC, NCR, Control Data Corporation (CDC), and Honeywell. These companies were grouped together because the market share of IBM was much higher than all of its competitors put together.
Midrange computers, or midrange systems, were a class of computer systems that fell in between mainframe computers and microcomputers.
Following the introduction of the IBM Personal Computer, many other personal computer architectures became extinct within just a few years. It led to a wave of IBM PC compatible systems being released.
The history of the personal computer as a mass-market consumer electronic device began with the microcomputer revolution of the 1970s. A personal computer is one intended for interactive individual use, as opposed to a mainframe computer where the end user's requests are filtered through operating staff, or a time-sharing system in which one large processor is shared by many individuals. After the development of the microprocessor, individual personal computers were low enough in cost that they eventually became affordable consumer goods. Early personal computers – generally called microcomputers – were sold often in electronic kit form and in limited numbers, and were of interest mostly to hobbyists and technicians.
In computer architecture, 16-bit integers, memory addresses, or other data units are those that are 16 bits wide. Also, 16-bit central processing unit (CPU) and arithmetic logic unit (ALU) architectures are those that are based on registers, address buses, or data buses of that size. 16-bit microcomputers are microcomputers that use 16-bit microprocessors.
The following outline is provided as an overview of and topical guide to computing:
Computers can be classified, or typed, in many ways. Some common classifications of computers are given below.
BASIC-8, is a BASIC programming language for the Digital Equipment (DEC) PDP-8 series minicomputers. It was the first BASIC dialect released by the company, and its success led DEC to produce new BASICs for its future machines, notably BASIC-PLUS for the PDP-11 series. DEC's adoption of BASIC cemented the use of the language as the standard educational and utility programming language of its era, which combined with its small system requirements, made BASIC the major language during the launch of microcomputers in the mid-1970s.
References
↑ Henderson, Rebecca M.; Newell, Richard G., eds. (2011). Accelerating Energy Innovation: Insights from Multiple Sectors. Chicago: University of Chicago Press. p.180. ISBN978-0226326832.
↑ Huang, Han-Way (2014). The Atmel AVR Microcontroller: MEGA and XMEGA in Assembly and C. Australia; United Kingdom: Delmar Cengage Learning. p.4. ISBN978-1133607298.
↑ "Minicomputer". Britannica.com. Minicomputer... the term was introduced in the mid-1960s.
↑ Patnaik, L. M.; Anvekar, D. K. (July 1982). "Case study of a microcomputer-minicomputer link". Journal of Microcomputer Applications. 5 (3): 225–230. doi:10.1016/0745-7138(82)90004-5.
↑ Goodwins, Rupert (February 12, 2011). "DEC's 40 years of innovation". ZDNet. p.4. Archived from the original on October 11, 2017. The term was coined by then DEC UK head John Leng, who sent a sales report saying, "Here is the latest minicomputer activity in the land of miniskirts as I drive around in my Mini Minor".
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