DescriptionDECSYSTEM-20 Introduction and Reference Card at Columbia University.jpg
English: From the Columbia University Center for Computing Activities, two documents used in 1980 that were related to using their main computing system at the time, the DECSYSTEM-20 and its TOPS-20 operating system. One is a 12-page Introduction, printed 2-up and dated May 1980, and the other is a front-and-back Reference Card, dated July 1979.
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