The design innovations in the IBM 3803 Tape Control Unit and the IBM 3420 Magnetic Tape Unit are discussed. The new design concepts include a full readback parity check, a system of microprogram control that obtains high operating rates through overlap of channel control and motion control functions, a new phase-error detection system, a modified dual-density recording feature and a new interface between the control unit and tape drive. The combination of novel error detection methods, control features and programming support (including an expanded scheme of on-line diagnostics) contributes to greatly improved total system performance over previous models of tape subsystems.
Note: The Institute of Electrical and Electronics Engineers, Incorporated is distributing this Article with permission of the International Business Machines Corporation (IBM) who is the exclusive owner. The recipient of this Article may not assign, sublicense, lease, rent or otherwise transfer, reproduce, prepare derivative works, publicly display or perform, or distribute the Article.