Browse Prior Art Database

Magnetic Record Copying and Verification

IP.com Disclosure Number: IPCOM000074726D
Original Publication Date: 1971-Jun-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 2 page(s) / 54K

Publishing Venue

IBM

Related People

Carey, EB: AUTHOR

Abstract

A master magnetic record is simultaneously copied and verified by comparing the number of signals recorded on each copy with the number of signals read from the master.

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Magnetic Record Copying and Verification

A master magnetic record is simultaneously copied and verified by comparing the number of signals recorded on each copy with the number of signals read from the master.

Magnetic tape on a master transport is moved past a read head, which supplies electrical signals representing the information on the master tape to four slave transports. A write head associated with each slave records a copy of the information on the master tape on each of four slave tapes. A typical magnetic record copier is the INFONICS Model SRC cassette duplicator.

Information serially recorded on the tape with alternating clock pulses and data pulses (presence is a 1-bit, absence is a 0-bit) may be verified by separating clock pulses from the data pulses, counting the latter, and comparing the count to a desired count equal to the number of data pulses known to be recorded on the master tape. If there are two channels on each tape, eight verification circuits are required.

Each verification circuit examines the amplitude of the pulses read and blocks utilization of any pulses which are either too high or low. The clock pulses are blocked by a timed signal and a timer is operated for the period between two clock signals. The timer identifies data bits occurring between two clock pulses (using sample pulses generated by the low-check circuit as described in IBM Technical Disclosure Bulletin dated October, 1969, page 670) as "correct", "early", or late....