Browse Prior Art Database

Continuous Trackstepping Up During Searching a Magnetic Card

IP.com Disclosure Number: IPCOM000074671D
Original Publication Date: 1971-May-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Smith, LG: AUTHOR

Abstract

For many applications all of the tracks recorded on the magnetic card of a Magnetic Card "SELECTRIC" Typewriter System (MC/ST) need not be read.

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Continuous Trackstepping Up During Searching a Magnetic Card

For many applications all of the tracks recorded on the magnetic card of a Magnetic Card "SELECTRIC" Typewriter System (MC/ST) need not be read.

For instance it may be determined by reading an abstract track (track 1) that only certain of the other tracks contain records of interest. Illustrated is a flow diagram of a system for increasing the output of such a system by a look-ahead technique which is used to determine whether the next track, as the magnetic head is stepped across the card, is to be read, and if not the head is not allowed to settle.

A track-address register (TKAD) which contains the current track location on the card of the read/record head, and a track counter (TKCTR) which contains the track location on the card of the index record to be analyzed are used.

On the abstract track, characters of a particular record are analyzed and if it is determined that an index record recorded on the card must be searched in detail, the read/record head is moved to the track where the actual track address is equal to that set in the track counter. The track-address register is always increased by one automatically for each track step-down. When a track step-up operation is initiated, a test is made on the contents of the track address register and the track counter. If the track counter count less the track address count equals one, a normal track step-up is performed. That is, operation will stop a...