MINICOMPUTERS: HISTORY, CHARACTERISTICS, USES, EXAMPLES - TECHNOLOGY - 2025

The minicomputers are a computer class who own most of the capabilities and features of a mainframe, but are smaller in physical size. A minicomputer can also be called as a mid-range computer.

They are mainly used as small or mid-range servers, where medium-sized commercial and scientific applications can operate. However, the use of the term minicomputer has decreased and merged with that of server.

Source: flickr.com

When single-chip CPU microprocessors appeared, beginning with the Intel 4004 in 1971, the term minicomputer evolved into a machine that falls in the mid-range of the computing spectrum, between the smallest macrocomputers and microcomputers.

A minicomputer fills the space between the macrocomputer and the microcomputer. It is smaller, less expensive and less powerful than the first, but larger, more expensive and more powerful than the second. You can operate with many users simultaneously.

Minicomputers versus macrocomputers

They were designed for the control of processes, as well as the transmission and switching of data, while the macrocomputers emphasized the storage, processing and calculation of data.

The macrocomputers required specialized rooms and technicians for their operation, thus separating the user from the computer, while the microcomputers were designed for direct and personal interaction with the programmer.

Minicomputers used to be the only option for businesses. Now, many companies are turning to personal computer networks to accomplish the same thing, but faster and cheaper.

History

Minicomputers were first developed by IBM, primarily for business applications and services that required the performance and efficiency of macrocomputers.

1960s

One of the first successful minicomputers was the 12-bit PDP-8, from Digital Equipment Corporation (DEC), built with digital transistors. It was released in 1964.

Minicomputers grew by having relatively high processing power and capacity.

The 7400 series of integrated circuits began to appear in minicomputers in the late 1960s.

In the 1970s, it was the hardware that was used to project the computer-aided design (CAD) industry and other similar industries.

Minicomputers were powerful systems, running multi-tasking and multi-user operating systems such as VMS and Unix.

At the launch of the Altair 8800 in 1975, Radio Electronics magazine referred to this system as a minicomputer, although the term microcomputer for personal computers with single-chip microprocessors soon became common.

The minicomputer was about to be overshadowed by integrated circuit technology, which would be used to build smaller, more affordable computers.

Fall of the 80s and 90s

The decline in the use of minicomputers occurred due to the lower cost of microprocessor-based hardware, the emergence of low-cost local area network systems, and the emergence of the 80286 and 80386 microprocessors.

The result was that minicomputers and terminals were replaced by file servers and networked personal computers in the second half of the 1980s.

During the 1990s the shift from minicomputers to inexpensive PC networks was consolidated with the development of various versions of the Unix system, running on the Intel x86 microprocessor architecture.

As the minicomputer fell to generic Unix servers and Intel-based PCs, almost all minicomputer companies, such as DEC, Data General, Computervision, and Honeywell, either collapsed or merged.

Today only a few proprietary minicomputer architectures survive. The IBM System / 38 operating system, which introduced many advanced concepts, lives on with the IBM AS / 400.

characteristics

The minicomputers were designed for easy connection to scientific instruments and other input / output devices, with a simple architecture, built using fast transistors, and programmed in assembly language, with little support for high-level languages.

Accessibility

Although the initial growth of minicomputers was due to their use as controllers of scientific instruments and data loggers, their most attractive feature turned out to be their accessibility.

Scientists and researchers could now buy their own computer and run it themselves in their own laboratories.

In addition, they had full access to the internal parts of the machine. The simplified architecture made it possible for a smart student to reconfigure the minicomputer to do something the manufacturer had not envisioned.

Researchers began using minicomputers for all sorts of new purposes. Manufacturers adapted later versions of these machines to the changing demands of the market.

Multiprocessing

Minicomputers can contain one or more processors, support multiprocessing and multitasking, and are generally resistant to high workloads.

Each person using a minicomputer has his own terminal connected by cable or modem to the computer. A terminal is not a computer, it is basically a keyboard and a monitor.

The minicomputer spends time on one person's task, then moves on to the next task, and so on, juggling work, depending on which tasks it deems to be the most important to perform.

If only one user uses the minicomputer, this can be a fast machine. However, when many users are on the system, it starts to slow down: you can type something and then wait a minute before seeing a response on the screen.

Size

Minicomputers were designed to be less complex than macrocomputers, but still provide multiple terminals for multiple users.

Although smaller than macrocomputers, minicomputers are more powerful than personal computers.

They typically take up few 19-inch rack cabinets, compared to large macrocomputers that could fill a room.

However, compared to macrocomputers, many of these systems were slower, had less memory, and could not be integrated into larger networks.

Applications

Minicomputers are used for scientific and engineering computing, business transaction processing, file management, and database administration. They are often referred to now as small or medium servers.

Functional tasks

The minicomputers were used in the different sectors of the companies in order to download the multiple tasks carried out by the macrocomputers.

They also pioneered and created departmental computing within the largest organizations. Smaller groups could buy, install, and maintain their own computers for private use.

In this way, computing began to migrate from being a single large central computer operation to use based on functional needs, defined by individual departments within a government, corporation or university.

A network of minicomputers can be created to allow a large library with its different branches to build its own internal network. This network is more powerful than the one handled by a macrocomputer. This provides flexibility and innovation at all levels.

Programming

Perhaps the most important contribution of minicomputers was the diversification of the programming itself.

They made it possible for more people to get involved in programming, thus increasing the rate of innovation in the art of software, including improving the user interfaces necessary for personal computing.

Process control

Minicomputers are primarily used by companies for manufacturing process control, engineering design, science experiments, communication systems, and many more. Process control has two main functions: data acquisition and feedback.

For example, factories use minicomputers to control the manufacturing process. If a problem appears anywhere in the process, acknowledge the change and make any necessary adjustments.

Data management

The minicomputers that are used for data management can perform any task related to the data, as they can take, restore or generate data.

Communication

Minicomputers act as an interface between the human operator and a larger processor.

With the help of a minicomputer the user can perform operations such as error checking and then can use the device to make adjustments as well.

Examples

PDP-8

The PDP-8 was the prototype for the early minicomputers. It was designed to be programmed in assembly language. It was simple (physically, logically and electrically) to connect a wide variety of input / output devices and scientific instruments.

Source: flickr.com

It had only 4,096 words of memory, and its word length was 12 bits, very short even by the standards of the time.

The word is the smallest piece of memory that a program can refer to independently. The size of the word limits the complexity of the instruction set and the efficiency of mathematical operations.

Both the short word and the small memory of the PDP-8 made it relatively unpowered for the moment, but its low price made up for it.

Hewlett-Packard HP-3000 Series

The HP 3000 series is a family of minicomputers released by Hewlett-Packard in 1972. It was designed to be the first minicomputer delivered with a full time-sharing operating system.

The first model of the 3000 was withdrawn from the market during 1973 until improvements in speed and stability of the operating system were achieved.

After its reintroduction in 1974, it finally became known as a reliable and powerful business system, regularly winning business for HP at companies using IBM macrocomputers.

The initial name by which Hewlett-Packard referred to the minicomputer was System / 3000, and then called it HP-3000. Later, HP renamed the minicomputer the HP e3000 to emphasize the compatibility of the system with the use of the Internet and the Web.

Other minicomputers

- CDC 160A and CDC 1700 from Control Data.

- VAX and DEC PDP series.

- Data General Nova.

- Interdata 7/32 and 8/32.

- Texas Instruments TI-990.

- K-202, the first Polish minicomputer.

References

1. Techopedia (2019). Minicomputer. Taken from: ceilingpedia.com.
2. Wikipedia, the free encyclopedia (2019). Minicomputer. Taken from: en.wikipedia.org.
3. Dinesh Thakur (2019). What is a Minicomputer? - Definition. Ecomputer Notes. Taken from: ecomputernotes.com.
4. Engineering and Technology History Wiki (2019). Rise and Fall of Minicomputers. Taken from: ethw.org.
5. Encyclopaedia Britannica (2019). Minicomputer. Taken from: britannica.com.
6. Microcontrollers Lab (2019). Difference between Mainframes and Mini Computers. Taken from: microcontrollerslab.com.