Cipher 900 9 Track Tape Drive

    This device is a so-called "dual mode" tape drive that reads/writes at either 800 or 1600 bpi(bits per inch). 800 bpi is processed using NRZI (Non Return to Zero Indiscriminate); 1600 bpi uses PE (Phase Encoding) techniques.

    Tape motion is controlled by a friction capstan with a 180 degree tape wrap. Reel inertia and tape slack are controlled by vacuum loops with a maximum read/write speed of 120 inches per second. The reel servos are controlled by feedback of the tape loop's position in the vacuum columns.

    The drive contains two internal PC boards; the data board, which handles the analogue and digital data streams, and the servo/control board which controls all the other functions. The machine is microprocessor controlled using a Zilog Z-80.

    I have two of these devices in my collection; both of which are currently inoperable.

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