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Browse Prior Art Database

On The Fly Interrecord Gap Formation

IP.com Disclosure Number: IPCOM000090088D
Original Publication Date: 1969-Jan-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Badum, PJ: AUTHOR

Abstract

Tape records are often written and read by drives having different operating speeds and different interrecord gap lengths. High-speed drives require larger gaps, but generally have the buffer capacity to handle long record blocks. Low-speed drives use small gaps, but require them between each set of adjacent records. Creation of a tape that can be handled by either speed drive is achieved by writing it on a high-speed drive with long interrecord gaps between blocks of records and short gaps between adjacent records. These short gaps are created on-the-fly and are ignored by the high-speed drive during read operations. They permit the low-speed drive to stop as necessary between records in the block.

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On The Fly Interrecord Gap Formation

Tape records are often written and read by drives having different operating speeds and different interrecord gap lengths. High-speed drives require larger gaps, but generally have the buffer capacity to handle long record blocks. Low- speed drives use small gaps, but require them between each set of adjacent records. Creation of a tape that can be handled by either speed drive is achieved by writing it on a high-speed drive with long interrecord gaps between blocks of records and short gaps between adjacent records. These short gaps are created on-the-fly and are ignored by the high-speed drive during read operations. They permit the low-speed drive to stop as necessary between records in the block.

This circuitry is provided in the high-speed drive for creating short gaps on- the-fly. This circuitry responds to Go commands received from the control unit. The Go command signal drops for the interval T0 to T1 after each record and for a longer period at the end of a record block. When the Go command drops, And 10 is disabled, dropping the Write Enable output and preventing further recording on the tape. At the same time, Inverter I11 supplies a signal through Or 12 to And 13, allowing 13 to gate pulses from the capstan displacement transducer 14 to gap counter 15. Counter 15 counts out a small gap length and then overflows at T2, conditioning its output line 16. While it is counting, I11 is active to supply an input to And 18,...