Contributor(s): Sharon Shea and David Higgins

A microcomputer is a complete computer on a small scale, designed for use by one person at a time. An antiquated term, a microcomputer is now primarily called a personal computer (PC), or a device based on a single-chip microprocessor. Common microcomputers include laptops and desktops. Beyond standard PCs, microcomputers also include some calculators, mobile phones, notebooks, workstations and embedded systems.

Smaller than a mainframe or minicomputer, a microcomputer uses a single integrated semiconductor chip for its central processing unit (CPU). They also contain memory in the form of read-only memory (ROM) and random access memory (RAM), input/output (I/O) ports, and a bus or system of interconnecting wires, all housed in a single unit usually referred to as a motherboard.

Common I/O devices include keyboards, monitors, printers and external storage.

History of microcomputers

The term microcomputer dates back to the 1970s. The advent of the Intel 4004 microprocessor in 1971, and later the Intel 8008 and Intel 8080 microprocessor in 1972 and 1974 respectively, paved the path to the creation of the microcomputer.

The first microcomputer was the Micral, released in 1973 by Réalisation d'Études Électroniques (R2E). Based on the Intel 8008, it was the first non-kit computer based on a microprocessor. In 1974, the Intel 8008-based MCM/70 microcomputer was released by Micro Computer Machines Inc. (later known as MCM Computers).

Though released after the Micral and MCM/70, the Altair 8800 is often considered the first successful commercial microcomputer. Released in 1974, it was designed by Micro Instrumentation Telemetry Systems (MITS) and was based on the Intel 8080 microprocessor. It retailed for around $400 in kit form, $600 assembled ($2,045 and $3,067 in 2018 dollars, respectively).

An Altair 8800 lies on display at the Microsoft Visitor Center April 6, 2005 in Redmond, Wash.
An Altair 8800 lies on display at the Microsoft Visitor Center April 6, 2005 in Redmond, Wash.

As microprocessor chip design matured, so did the processing capacity of microcomputers. By the 1980s, microcomputers were being used for more than games and computer-based recreation, finding widespread use in personal computing, workstations and academia. By the 1990s, microcomputers were being produced as pocket-sized personal digital assistants (PDAs), and later came in the form of cellphones and portable music players.

Microcomputer applications

Personal microcomputers are often used for education and entertainment. Beyond laptops and desktops, microcomputers can include video game consoles, computerized electronics and smartphones.

In the workplace, microcomputers have been used for applications including data and word processing, electronic spreadsheets, professional presentation and graphics programs, communications and database management systems. They have been used in business for tasks such as bookkeeping, inventory and communication; in medical settings to record and recall patient data, manage healthcare plans, complete schedule and for data processing; in financial institutions to record transactions, track billing, prepare financial statements and payrolls, and auditing; and in military applications for training devices, among other uses.

Microcomputers and IoT

The Raspberry Pi, a small, single-board computer, was once self-described as a microcontroller. Today used for internet of things (IoT) prototyping, education and applications, the Raspberry Pi and other single-board computers, such as those from Arduino, Intel and Particle, are more often described as microcontrollers than microcomputers.

Microcomputers can be used for similar tasks in IoT applications as microcontrollers, however. Certain IoT devices, such as smart TVs, refrigerators and other connected appliances, are sometimes referred to as microcomputers.

Where a microcomputer fits in

The ascending hierarchy of general computer sizes is as follows:

  • Embedded systems, which are fixed inside something and don't support direct human interaction but nonetheless meet all other criteria of microcomputers;
  • Microcomputers;
  • Workstations, formerly described as a more powerful personal computer for special applications;
  • Minicomputers, now called mid-range servers;
  • Mainframes, which are now usually referred to by manufacturers as large servers;
  • Supercomputers, large servers, sometimes including systems of computers using parallel processing; and
  • Parallel processing system, a system of interconnected computers that work on the same application together, sharing tasks that can be performed concurrently.

Microcomputers vs. microcontrollers
A microcontroller is an integrated circuit (IC) designed to govern a specific operation in an embedded system. These single chips have onboard RAM, ROM and peripherals.

Microcontrollers have been referred to as single microcomputers.

Microcomputers vs. microprocessors
A microprocessor is a computer processor on a microchip that contains all or most CPU functions. Microprocessors do not have RAM, ROM or other peripherals. As such, microprocessors cannot perform standalone tasks. Rather, systems such as microcomputers, which contain microprocessors, can be programmed to perform functions on data by writing specific instructions for their microprocessors into their memory.

A microcomputer can technically be described as the combination of a microprocessor and its peripheral I/O devices, circuitry and memory -- just not on a single chip.

Microcomputers vs. minicomputers
While microcomputers generally refer to laptops or desktops, minicomputers were a variety of computer primarily used in the 1960s to 1980s. Minicomputers were larger than microcomputers -- some stood more than 6 feet tall and weighted up to 700 pounds -- and boasted higher processing speeds at a significantly smaller size and price than mainframes and supercomputers available at the time. While microcomputers were often used at home and in the office, minicomputers were primarily found in academia, research labs and small companies, and they were used for word processing, accounting and teaching aids.

Digital Equipment Corporation's Programmed Data Processor-1, or PDP-1, was announced in 1960 and sold for $120,000 ($1,021,776 in 2018 dollars). Its descendent, the PDP-8, was introduced in 1965 and sold for nearly $18,500 ($148,022 in 2018 dollars). Considered one of the most successful minicomputers and first example of a commercial minicomputer, the 12-bit PDP-8 has been compared to the size of a small household refrigerator.

Minicomputers did not contain microprocessors. In the 1980s, the minicomputer's prevalence declined as microprocessors became more powerful and available at lower cost.

An antiquated term, minicomputers are often referred to as midrange computers.

Microcomputers vs. mainframes
A mainframe computer is a high-performance computer used for large-scale computing purposes that require greater availability and security than small-scale machines can provide. Mainframes can process requests from a number of users simultaneously, whereas a microcomputer is designed to be used by one person at a time. As such, a mainframe computer can be described as a system that interconnects a number of microcomputers.

This was last updated in December 2018

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