First generation computers were largely out of reach of schools and hobbyists who wished to build their own, largely because of the cost of the large number of vacuum tubes required (though relay-based computer projects were undertaken). The fourth generation (VLSI) was also largely out of reach, too, due to most of the design work being inside the integrated circuit package (though this barrier, too, was later removed). So, second and third generation computer design (transistors and LSI) were perhaps the best suited to being undertaken by schools and hobbyists.A.Wilkinson (1968). Computer Models, Edward Arnold, UK, SBN 7131 1515 X
