Definition , on display at the
Computer History Museum The term "minicomputer" developed in the 1960s to describe the smaller computers that became possible with the use of
transistors and
core memory technologies, minimal
instruction sets and less expensive
peripherals such as the ubiquitous
Teletype Model 33 ASR. They usually took up one or a few
19-inch rack cabinets, compared with the large
mainframes that could fill a room. Later minicomputers tended to be more compact, and while still distinct in terms of
architecture and function, some models eventually shrank to a similar size as large microcomputers. 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 compact
vacuum tube-based
drum machines, such as the
UNIVAC 1101 (1950), and the
Bendix G-15 and
LGP-30 (both 1956), all of which shared 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 such as the ASR 33. Another common difference was that most small machines before the 1970s were not "general purpose", in that they were designed for a specific role such as engineering,
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. DEC wrote, regarding their PDP-5, that it was "the world’s first commercially produced minicomputer". 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. Some of this is no doubt due to DEC's widespread use of the term starting in the mid-1960s. Smaller systems, including those from DEC such as the
PDP-5 and
LINC, 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 () places it in an entirely different market segment than earlier examples such as the CDC 160. In contemporary terms, the PDP-8 was a runaway success, ultimately selling 50,000 examples. 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. in 1978 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. In a 1970 survey,
The New York Times suggested a consensus definition of a minicomputer as a machine costing less than (), 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. The typical customer was a department in a large company, at which the finance department's mainframe was too busy to serve others. 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 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 such as
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. 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 such as 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 Minicomputer companies historically competed on the price and speed of their computers, instead of marketing and advertising. By the early 1980s, the 16-bit minicomputer 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 such as 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
workstations opened new markets for
graphics-based systems that the terminal-oriented minis could not even address. Minis remained 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 yield 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. 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. 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 such as
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.
Industrial impact and heritage Database software is an example of an area where a variety of companies emerged that built
turnkey systems around minicomputers with specialized software and, in many cases, custom peripherals that addressed specialized problems such as
computer-aided design,
computer-aided manufacturing,
process control,
manufacturing resource planning, and so on. Many if not most minicomputers were sold through these
original equipment manufacturers and
value-added resellers. Several pioneering computer companies first built minicomputers, such as
DEC,
Data General, and
Hewlett-Packard (HP) (who later referred to its
HP 3000 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. 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.
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.{{cite web ==Examples==