What it is and the problem it solves
A personal computer is a computer designed for personal use, typically for word processing, web browsing, email, spreadsheets and video calling. It is operated directly by an end user, not by an expert, administrator or technician, and unlike mainframes and minicomputers it does not rely on time-sharing by many people at once. In the 1960s, by contrast, institutional and corporate computer owners had to write their own programs to do any useful work. Personal computer software is usually supplied ready to run, developed independently of the hardware maker.
How it works
The personal computer rests on semiconductor technology. Robert Noyce developed the silicon integrated circuit at Fairchild in 1959, and Federico Faggin developed the silicon-gate MOS circuit there in 1968. Faggin then used that technology to build the first single-chip microprocessor, the Intel 4004, in 1971.
In a typical desktop, the motherboard connects the processor, memory and peripheral devices. Expansion cards attach through buses such as PCI and PCI Express. An operating system manages memory, input and output, networking and files, and applications rely on that system software.
What works
The Micral N, built from 1972 around the Intel 8008, was the earliest commercial, non-kit microprocessor-based microcomputer; a few hundred were sold. The Altair 8800 of 1974, based on the Intel 8080, is widely recognised as the first commercially successful personal computer. Its bus became the S-100 standard and its first language was Altair BASIC, Microsoft’s founding product.
In 1977 the Commodore PET, Apple II and TRS-80, known together as the “1977 trinity”, brought ready-assembled machines to a wider public. IBM’s 5150, introduced on 12 August 1981 at US$1,565, had an open architecture that set the mass-market standard. The 1984 Macintosh was the first successful mass-market mouse-driven computer with a graphical interface. About 48,000 personal computers shipped in 1977 and 125 million in 2001.
What does not
Early personal computers were very expensive. The mid-1970s kits interested mostly hobbyists and technicians, who entered programs on toggle switches and read results from front-panel lamps. Practical use needed an added serial terminal or expansion cards for a keyboard, display, disk drives and printers.
The 1973 Xerox Alto had a graphical interface that later served as inspiration for the Macintosh and Windows, but it was a demonstration project, never commercialised because its parts were too expensive. Early command-line systems made users remember a large range of commands.
What it changes
Personal computer software came to be developed and distributed independently of the hardware makers. Since the early 1990s Microsoft operating systems and Intel x86 processors, together called Wintel, have dominated the market, so “PC” now normally means a Windows machine. Home and business computers lost their technical distinction after the IBM PC took hold.
Communication changed what the machines were used for: bulletin board systems and online services became common after 1978, commercial Internet providers emerged in the late 1980s and the World Wide Web opened to the public in 1991. Time magazine named the personal computer Machine of the Year in 1982.
Is it worth your time
Yes, if you want to know how a category formed. The definition is simple: one person operating the machine directly. The history adds the order of events, with semiconductor advances first, microprocessors in 1971, the first machines in the early 1970s and mass-market products after 1977. Several machines carry the title of first, including the Micral N, the Altair 8800 and the 1973 SCAMP prototype, which PC Magazine called “the world’s first personal computer” in 1983.
