MAGNETIC TAPE UNIT CONTROL SYSTEM

摘要

Instruction decoding means decodes a received instruction. The instruction decoding means comprises a plurality of circuits each representing a different instruction and each providing an output signal at its output and decoding control means connected to each of the circuits for directing the decoded instruction in accordance with its contents to the input of a selected one of said circuits. Each of a plurality of storage circuits is coupled to the output of a corresponding one of the circuits of the instruction decoding means for storing the output signals of said circuits. A read and write circuit connected to the outputs of some of the storage circuits designates a selected one of a readout and a writein instruction and stores the designation in accordance with the contents of the storage circuits to which the read and write circuit is connected. A packing density circuit connected to the outputs of the others of the storage circuits designates a selected one of a first packing density and a second packing density and stores the designation in accordance with the contents of the storage circuits to which the packing density circuit is connected. The output of the read and write circuit is coupled to an input of the packing density circuit for designating the second packing density in the packing density circuit when the read and write circuit designates a readout. A packing density identification burst detecting means has an input coupled to a readout head of a magnetic tape for detecting the existence on the magnetic tape of a packing density identification burst. The output of the packing density identification burst detecting means is coupled to an input of the packing density circuit for designating the first packing density in said packing density circuit when the packing density identification burst detecting means fails to detect a packing density identification burst in the magnetic tape.