Reading passage
For most of the twentieth century, a computer was a room-sized machine attended by specialists, owned by governments, universities or large corporations, and operated through punched cards rather than keyboards. The idea that an individual might possess such a machine at home would have seemed absurd to the engineers of the 1950s. Yet within three decades, computers had moved from air-conditioned laboratories onto office desks and kitchen tables, a migration that ranks among the fastest technological adoptions in history.
The foundations of this transformation were laid in electronics. The transistor, invented at Bell Laboratories in 1947, replaced the fragile vacuum tubes of early machines, cutting size, cost and heat. A decade later, the integrated circuit allowed multiple transistors to be fabricated on a single piece of silicon. These advances followed a pattern later described by Gordon Moore, who observed in 1965 that the number of components on a chip was doubling roughly every year, a prediction revised to every two years and subsequently known as Moore's law. Computing power was becoming dramatically cheaper, and somebody was bound to exploit that fact.
That somebody, or rather several somebodies, emerged in the 1970s. In 1971 Intel released the 4004, the first commercially available microprocessor, which placed the essential circuits of a central processing unit on one chip. Hobbyist magazines soon published designs for build-it-yourself computers, and in 1975 the Altair 8800 appeared on the cover of Popular Electronics. The Altair had no keyboard or screen; results were read from flashing lights. Nevertheless, it inspired a generation of enthusiasts, including two young programmers, Bill Gates and Paul Allen, who wrote a version of the BASIC language for the machine.
The true arrival of the personal computer is usually dated to 1977, when three machines reached the market: the Apple II, the Commodore PET and the Tandy TRS-80. Unlike the Altair, these were complete, ready-to-use products with keyboards and displays, aimed not at engineers but at schools, small businesses and curious households. The Apple II in particular, with its colour graphics and expanding library of software, demonstrated that ordinary people would pay for computing if it was packaged as an appliance rather than a science project.
Business acceptance came in 1981 with the IBM Personal Computer. IBM's reputation persuaded conservative corporations that desktop machines were serious tools, and its decision to use an open architecture, built largely from other companies' components, allowed competitors to manufacture compatible machines. The software industry grew alongside the hardware. The spreadsheet program VisiCalc, released in 1979, had already shown that a personal computer could perform useful work; later word processors and databases made the machines indispensable in offices. By the mid-1980s, personal computer sales were measured in the tens of millions annually.
The next challenge was usability. Early machines demanded that users memorise typed commands, which limited their appeal. Xerox's research centre had pioneered the graphical user interface, with windows, icons and a mouse, but it was Apple's Macintosh in 1984 that brought these ideas to a mass audience, followed by Microsoft's Windows software. Once computers could be operated by pointing rather than typing, their potential market expanded enormously, touching users with no interest in programming whatsoever.
The social impact of the personal computer has been extensively debated. Supporters credit it with democratising access to information and creating entire new industries, from video games to desktop publishing. Critics point to the digital divide separating those who could afford the technology from those who could not, and to workplace anxieties about automation. What is not disputed is the speed of the change. A device that did not exist as a consumer product in 1975 was present in most households in wealthy countries by 2000.
Today, the descendants of those early machines include laptops, tablets and smartphones, and computing power that once filled a building fits into a pocket. The personal computer's story is therefore often told as a lesson in unintended consequences: a tool designed for spreadsheets and word processing became, once connected to networks, a medium for shopping, education and social life. The revolution, in other words, lay not in the machine itself but in what ordinary people chose to do with it.