Computers of the '70s

The 1970s were a heady time in the computer industry. The decade saw many notable inventions and developments, especially in the areas of the personal computer, networking and object-oriented programming. Innovators produced groundbreaking hardware and software. Several large organizations entered the industry or expanded during the decade, including Texas Instruments, Xerox and International Business Machines, or IBM. Some companies, such as RCA, dipped their toes in industry waters, but quickly withdrew from the computer scene.

Beginning in the 1950s, business computer manufacturers like IBM produced large and, for the time, powerful machines allowing businesses to process information at faster rates than ever before. Data input involved punch cards and output required large printers like IBM’s 3800 printer that took up most of a large room. Mainframes, like the IBM System 370, were housed in air-conditioned facilities and recorded information on magnetic tape drives, although IBM invented floppy disks in 1971. Universities began purchasing mainframes to process research data. The expense and size of the mainframe and its housing requirements meant that most campuses had no more than one or two computers. Researchers carrying data on floppy disks from building to building wanted better ways to share computing. The creation of networks enabled researchers to use the systems from their offices and labs. Digital Equipment Corporation developed the minicomputer hardware architecture in 1971. These systems included typewriter-like input devices and cathode ray tube monitors but were almost as large as their mainframe counterparts.

The Local Area Network system developed in the late 1960s connected computers within an office or building using cables. The 1970s saw the development of the Wide Area Network that allowed connection outside the local area via telephone lines. In 1969, the Advanced Research Project Agency, a U.S. Department of Defense agency, developed ARPANET, connecting four California university computers. By 1971 the network had grown to 23 computers.

In 1975 IBM introduced the 5100 Portable PC. At 55 pounds, it wasn’t really portable, but it was self-contained and allowed the user to access the mainframe from a desktop.

By the early 1970s hobbyists had begun tinkering with computing machines in their homes. In 1974 Intel released the 8080, a 2 megahertz processing chip, and soon Information Management Services introduced the IMSAI computer kit and Micro Instrumentation and Telemetry Systems released the Altair kit, giving hobbyists do-it-yourself home computers. In 1977 Commodore built and sold the PET computer and Tandy/Radio Shack released the TRS-80 (affectionately known as the “Trash-80.”).

During the mid-1970s Steve Jobs and Steve Wozniak built the first Apple computer and demonstrated it at the Homebrew Computer Club. This model was followed quickly by the Apple II that enjoyed brisk sales. A new software company named Microsoft, founded by Bill Gates and Paul Allen, developed the Beginner All-purpose Symbolic Instruction Code software program to operate the Altair, naming it Altair BASIC. Hobbyist clubs were quick to share copies of the code prompting letters and legal action from Gates.

Microsoft made the decision to focus on software, contracting with IBM to write the operating system software for IBM personal computers, named IBM-DOS. In an unusual move, IBM agreed to allow Microsoft to license another version of the software named MS-DOS, thereby giving Microsoft entry into the burgeoning “DOS-compatible” computer hardware market. The 1970s were also a fertile decade for software programmers who produced computer-aided design, word-processing and spreadsheet software.