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The Third Computer Generation

Transistors became smaller and smaller which led to the integration of transistors and diodes in modules in the third computer generation beginning in 1962 (Vorndran 108).¹¹ The decreasing costs of computers also gave rise to minicomputers like the DEC PDP series, which sold like hotcakes in spite of their high price (Tanenbaum 10).¹²
In contrast to the second computer generation, the concept of multiprogramming allowed several programs to be loaded into the memory of a machine and the cycling through them whenever a job had to wait for I/O operations (Silberschatz and Galvin 8; Tanenbaum 9). Computer families such as the IBM System/360 were equipped with special hardware which decreased CPU idle time by keeping as many jobs in memory as possible, whereas in the second computer generation a job first had to be read from tape and finished before the next job could be computed (Tanenbaum 6). However, programmers had to wait for the results of their code since multiprogramming systems were still batch systems which spooled jobs on a disk (Silberschatz and Galvin 795).¹³
This changed with the introduction of time-sharing systems; according to Silberschatz and Galvin, the first of which were demonstrated in 1960, but didn't become common before the 1970s (11). Time-sharing systems gave programmers the illusion that they were working on their own system, enabling them to edit, compile, and run programs through a teletype terminal (Silberschatz and Galvin 799; Walker 441). In contrast to the second computer generation, computers reacted more or less in an interactive way to user input, making it necessary to develop interactive languages (Dix et al. 52). As a consequence, the role of the user became more important (Negroponte 111).¹⁴
One of the first of the previously mentioned interactive systems was CTSS, followed by MULTICS, and, later, UNIX (Tanenbaum 10).¹⁵ UNIX was not intended to be a system for novice users (Brennan 394): it was developed as a system by programmers for programmers (Tanenbaum 271-272).¹⁶ High-level programming languages like ALGOL, COBOL, and FORTRAN dominated software development. C became popular with the rise of UNIX (Tanenbaum 267). In addition, descriptive languages like PROLOG (PROgramming in LOGic) were introduced (Bauknecht and Zehnder 165).¹⁷

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