A personal computer (PC) is a multi-purpose computer whose size, capabilities, and price make it feasible for individual use. PCs are intended to be operated directly by an end user, rather than by a computer expert or technician. Computer time-sharing models that were typically used with larger, more expensive minicomputer and mainframesystems, to enable them be used by many people at the same time, are not used with PCs.
Early computer owners in the 1960s, invariably institutional or corporate, had to write their own programs to do any useful work with the machines. In the 2010s, personal computer users have access to a wide range of commercial software, free-of-charge software (“freeware”) and free and open-source software, which are provided in ready-to-run form. Software for personal computers is typically developed and distributed independently from the hardware or OS manufacturers. Many personal computer users no longer need to write their own programs to make any use of a personal computer, although end-user programming is still feasible. This contrasts with mobile systems, where software is often only available through a manufacturer-supported channel, and end-user program development may be discouraged by lack of support by the manufacturer.
Since the early 1990s, Microsoft operating systems and Intel hardware have dominated much of the personal computer market, first with MS-DOS and then with Windows. Alternatives to Microsoft’s Windows operating systems occupy a minority share of the industry. These include Apple’s macOS and free and open-source Unix-like operating systems such as Linux. Advanced Micro Devices (AMD) provides the main alternative to Intel’s processors.
History of Personal Computer
In the history of computing there were many examples of computers designed to be used by one person, as opposed to terminals connected to mainframe computers. It took a while for computers to be developed that meet the modern definition of a “personal computers”, one that is designed for one person, is easy to use, and is cheap enough for an individual to buy.
Using the narrow definition of “operated by one person”, the first personal computer was the ENIAC which became operational in 1946. It did not meet further definitions of affordable or easy to use. The Bendix G15 of 1956 was intended for use without an operating staff, and several hundred were made; it was too costly to be personally owned, however.
An example of an early single-user computer was the LGP-30, created in 1956 by Stan Frankel and used for science and engineering as well as basic data processing. It came with a retail price of $46,000—equivalent to about $423,000 today.
Introduced at the 1965 New York Worlds Fair, the Programma 101 was a printing programmable calculator described in advertisements as a “desktop computer”. It was manufactured by the Italian company Olivetti, and invented by the Italian engineer Pier Giorgio Perotto, inventor of the magnetic card system for program storage.
The Soviet MIR series of computers was developed from 1965 to 1969 in a group headed by Victor Glushkov. It was designed as a relatively small-scale computer for use in engineering and scientific applications, and contained a hardware implementation of a high-level programming language. Another innovative feature for that time was the user interface combining a keyboard with a monitor and light penfor correcting texts and drawing on screen. In what was later to be called the Mother of All Demos, SRIresearcher Douglas Engelbart in 1968 gave a preview of what would become the staples of daily working life in the 21st century: e-mail, hypertext, word processing, video conferencing, and the mouse. The demonstration required technical support staff and a mainframe time-sharing computer that were far too costly for individual business use at the time.
By the early 1970s, people in academic or research institutions had the opportunity for single-person use of a computer system in interactive mode for extended durations, although these systems would still have been too expensive to be owned by a single person. Early personal computers—generally called microcomputers—were often sold in a kit form and in limited volumes, and were of interest mostly to hobbyists and technicians. Minimal programming was done with toggle switches to enter instructions, and output was provided by front panel lamps. Practical use required adding peripherals such as keyboards, computer displays, disk drives, and printers. Micral N was the earliest commercial, non-kit microcomputer based on a microprocessor, the Intel 8008. It was built starting in 1972, and few hundred units were sold. This had been preceded by the Datapoint 2200 in 1970, for which the Intel 8008 had been commissioned, though not accepted for use. The CPU design implemented in the Datapoint 2200 became the basis for x86 architecture used in the original IBM PC and its descendants.
In 1973, the IBM Los Gatos Scientific Center developed a portable computer prototype called SCAMP (Special Computer APL Machine Portable) based on the IBM PALM processor with a Philips compact cassette drive, small CRT, and full function keyboard. SCAMP emulated an IBM 1130 minicomputer in order to run APL/1130. In 1973, APL was generally available only on mainframe computers, and most desktop sized microcomputers such as the Wang 2200 or HP 9800 offered only BASIC. Because SCAMP was the first to emulate APL/1130 performance on a portable, single user computer, PC Magazine in 1983 designated SCAMP a “revolutionary concept” and “the world’s first personal computer”. This seminal, single user portable computer now resides in the Smithsonian Institution, Washington, D.C.. Successful demonstrations of the 1973 SCAMP prototype led to the IBM 5100 portable microcomputer launched in 1975 with the ability to be programmed in both APL and BASIC for engineers, analysts, statisticians, and other business problem-solvers. In the late 1960s such a machine would have been nearly as large as two desks and would have weighed about half a ton.
Another desktop portable APL machine, the MCM/70, was demonstrated in 1973 and shipped in 1974. It used the Intel 8008 processor.
A seminal step in personal computing was the 1973 Xerox Alto, developed at Xerox’s Palo Alto Research Center (PARC). It had a graphical user interface (GUI) which later served as inspiration for Apple’s Macintosh, and Microsoft’s Windows operating system. The Alto was a demonstration project, not commercialized, as the parts were too expensive to be affordable.
Also in 1973 Hewlett Packard introduced fully BASIC programmable microcomputers that fit entirely on top of a desk, including a keyboard, a small one-line display, and printer. The Wang 2200 microcomputer of 1973 had a full-size cathode ray tube (CRT) and cassette tape storage. These were generally expensive specialized computers sold for business or scientific uses. The introduction of the microprocessor, a single chip with all the circuitry that formerly occupied large cabinets, led to the proliferation of personal computers after 1975.
1974 saw the introduction of what is considered by many to be the first true “personal computer”, the Altair 8800 created by Micro Instrumentation and Telemetry Systems (MITS). Based on the 8-bit Intel 8080 Microprocessor, the Altair is widely recognized as the spark that ignited the microcomputer revolution as the first commercially successful personal computer. The computer bus designed for the Altair was to become a de facto standard in the form of the S-100 bus, and the first programming language for the machine was Microsoft’s founding product, Altair BASIC.
In 1976, Steve Jobs and Steve Wozniak sold the Apple I computer circuit board, which was fully prepared and contained about 30 chips. The Apple I computer differed from the other kit-style hobby computers of era. At the request of Paul Terrell, owner of the Byte Shop, Jobs and Wozniak were given their first purchase order, for 50 Apple I computers, only if the computers were assembled and tested and not a kit computer. Terrell wanted to have computers to sell to a wide range of users, not just experienced electronics hobbyists who had the soldering skills to assemble a computer kit. The Apple I as delivered was still technically a kit computer, as it did not have a power supply, case, or keyboard when it was delivered to the Byte Shop.
The first successfully mass marketed personal computer to be announced was the Commodore PET after being revealed in January 1977. However, it was back-ordered and not available until later that year. Three months later (April), the Apple II (usually referred to as the “Apple”) was announced with the first units being shipped 10 June, 1977, and the TRS-80 from Tandy Corporation / Tandy Radio Shack following in August 1977, which sold over 100,000 units during its lifetime. Together, these 3 machines were referred to as the “1977 trinity”. Mass-market, ready-assembled computers had arrived, and allowed a wider range of people to use computers, focusing more on software applications and less on development of the processor hardware.
During the early 1980s, home computers were further developed for household use, with software for personal productivity, programming and games. They typically could be used with a television already in the home as the computer display, with low-detail blocky graphics and a limited color range, and text about 40 characters wide by 25 characters tall. Sinclair Research, a UK company, produced the ZX Series—the ZX80 (1980), ZX81 (1981), and the ZX Spectrum; the latter was introduced in 1982, and totaled 8 million unit sold. Following came the Commodore 64, totaled 17 million units sold.
In the same year, the NEC PC-98 was introduced, which was a very popular personal computer that sold in more than 18 million units. Another famous personal computer, the revolutionary Amiga 1000, was unveiled by Commodore on July 23, 1985. The Amiga 1000 featured a multitasking, windowing operating system, color graphics with a 4096-color palette, stereo sound, Motorola 68000 CPU, 256 KB RAM, and 880 KB 3.5-inch disk drive, for US$1,295.
Somewhat larger and more expensive systems (for example, running CP/M), or sometimes a home computer with additional interfaces and devices, although still low-cost compared with minicomputers and mainframes, were aimed at office and small business use, typically using “high resolution” monitors capable of at least 80 column text display, and often no graphical or color drawing capability. Workstations were characterized by high-performance processors and graphics displays, with large-capacity local disk storage, networking capability, and running under a multitasking operating system. Eventually, due to the influence of the IBM PC on the personal computer market, personal computers and home computers lost any technical distinction. Business computers acquired color graphics capability and sound, and home computers and game systems users used the same processors and operating systems as office workers. Mass-market computers had graphics capabilities and memory comparable to dedicated workstations of a few years before. Even local area networking, originally a way to allow business computers to share expensive mass storage and peripherals, became a standard feature of personal computers used at home.
In 1982 “The Computer” was named Machine of the Year by Time magazine. In the 2010s, several companies such as Hewlett-Packard and Sony sold off their PC and laptop divisions. As a result, the personal computer was declared dead several times during this period.