Computer Collection Library

The IBM 700 Series

IBM's first generation mainframe computers, in two lines, scientific and commercial. The scientific line consisting of the 701, 704 and 709 were 36-bit binary machines with an accumulator architecture. The commercial line consisting of the 702 and the 705 I, II and III were character decimal machines with 5-character instructions but variable word length. All the 700 series used circuits based on vacuum tubes and point-contact diodes. The components were mounted in modules carrying up to 8 tubes each. The earlier 701 (introduced in 1951) and 702 used Williams tube memory, the later machines all used core memory. There was drum memory available for all types to extend the memory somewhat but the main mass storage was 7-track magnetic tape. The 701 and 702 used drives capable of 100 bpi, while all the later machines used drives that worked at 200 bpi. Each machine came with a card reader and printer, some also had a card punch.


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