A decade of shrinking machines
In the early 1970s, computers still belonged mostly to institutions. By the end of the decade, a person could buy one, assemble one from a kit, or play a computer-driven game in a bar or at home. The change came from a mix of technical progress, falling costs and the enthusiasm of small groups of hobbyists.
Minicomputers in labs and offices
Minicomputers, which had begun in the 1960s, spread widely through the 1970s. Digital Equipment’s PDP-11, introduced at the start of the decade, was influential, and companies such as Data General and Hewlett-Packard also sold small systems. They were used in laboratories, factories, schools and small businesses, often with a terminal for interactive work.
Software developed on these machines had a long reach. At Bell Labs, researchers working on a PDP-series minicomputer created Unix in the early 1970s and rewrote much of it in the C language in the middle of the decade. The result was an operating system that could be moved to different hardware with comparatively little effort, which was unusual then. Universities adopted it, and many later systems drew on its ideas.
The microprocessor
In 1971 Intel released the 4004, a processor on a single chip, designed for a calculator manufacturer. Later chips such as the 8008 and the 8080 in 1974 were more capable, and competitors including Motorola, MOS Technology and Zilog introduced their own. Single-chip processors made it much cheaper to build a computer, since the central part no longer had to be assembled from many separate circuits.
It is worth being careful about the word “first” here. Several companies worked on similar ideas around the same time, and historians describe the 4004 as an early commercial microprocessor rather than the only one. Its importance lies in the direction it pointed.
Hobby kits and the first home machines
In January 1975 a hobbyist magazine in the United States featured the Altair 8800, a kit computer based on the 8080 chip. It had switches and lights on the front and almost no software at first. It sold to enthusiasts who were happy to build and program it themselves, and it inspired many followers. Two young programmers wrote a version of the BASIC language for it and went on to found Microsoft.
Clubs were important. Groups of hobbyists met to share parts and programs, and the Homebrew Computer Club in California became especially well known. Steve Wozniak designed the Apple I, sold in 1976 as a circuit board for hobbyists to complete, and the Apple II followed in 1977 as a finished machine with a keyboard and color graphics. The same year, Commodore’s PET and Tandy’s TRS-80 reached stores, giving buyers an out-of-the-box option. Collectively these are sometimes called the “1977 trinity,” although there were many other brands and kits.
Software for these machines was limited but growing. Programs were stored on cassette tapes at first, and later on floppy disks. VisiCalc, a spreadsheet program released in 1979 for the Apple II, is often credited with showing that a small computer could be useful for business tasks.
Early video games
The 1970s were also the decade when games became a consumer technology. Magnavox’s Odyssey console appeared in 1972, and Atari’s Pong brought arcade play into bars and eventually homes. Arcade cabinets contained special-purpose electronics rather than general computers at first, but by the later 1970s microprocessors were common in them. Space Invaders, released in Japan in 1978, was a major hit.
At home, the Atari 2600, launched in 1977, popularized interchangeable game cartridges. On university mainframes and minicomputers, students wrote text-based adventure games, and a cave exploration game called Adventure circulated from the mid-1970s and inspired others.
Networks and interfaces
Research continued behind the scenes. Email was developed on ARPANET in the early 1970s and soon became its most popular use. At Xerox’s Palo Alto Research Center, researchers built the Alto, a personal workstation with a bitmapped screen and a mouse, along with experiments in local networking that led to Ethernet. Few people outside the research community saw this work, but its influence became clear in the 1980s.
Supercomputers also moved forward. The Cray-1, released in 1976, was a well-known example, although it was purchased by only a small number of national laboratories and similar customers.
Why the decade matters
The 1970s did not make computers common in ordinary households. A typical home still had no computer in 1979, and the machines that did exist were rough and expensive by later standards. What the decade changed was the idea of who a computer was for. When an individual could own one, a different kind of software, magazines, shops and communities began to appear, and these set up the rapid growth of the 1980s.