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Retry method and apparatus for use in a magnetic recording and reproducing system

  • US 3,984,814 A
  • Filed: 12/24/1974
  • Issued: 10/05/1976
  • Est. Priority Date: 12/24/1974
  • Status: Expired due to Term
First Claim
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1. A method for retrying commands received by a magnetic tape peripheral controller from a data processing unit coupled to said controller during the handling of error conditions occurring during the execution of read and write operations respectively in which information bytes of digital signals of a block having a predetermined format are read from a multichannel magnetic medium and written by a magnetic tape device on said multichannel magnetic medium, said device coupled to said controller, said controller including processing means, recovery means coupled to said device for assembling said digital signals into said bytes, said recovery means including activity detector means responsive to said signals to generate signals indicative of the rate at which said signals are being received, and indicator storage means coupled to said detector means and to said processing means, said method comprising the steps of:

  • a. generating output signals by said activity detector means during the monitoring of the reception of said digital signals received by said recovery means from said tape device corresponding to said bytes of said block being read by said tape device from said medium for a predetermined number of time intervals during the execution of an operation by said controller processing means specified by a command received from said data processing unit;

    b. storing a plurality of error signal indications in said indicator storage means in response to said output signals from said activity detector means which define the profile characteristics of said block detected during step (a); and

    ,c. generating signals by said controller processing means for initiating a retry of said command and re-execution of said operation upon the completion of said operation upon detecting an error condition only when said error signal indications stored in indicator storage means signal that said profile characteristics of said block read during said operation indicate that said device can reliably retry said operation.

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