Browse Prior Art Database

Correcting Line To Track Correspondence

IP.com Disclosure Number: IPCOM000076668D
Original Publication Date: 1972-Apr-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Hoe, JW: AUTHOR

Abstract

To conserve tracks on a magnetic card in an IBM Magnetic Card "SELECTRIC" Typewriter (MC/ST) it is the usual practice with "white space" on a page, such as occurs between the internal address and the body of a letter, which requires a number of line advances, to not record a carrier return (CR) code for each line advance. Instead for all carrier returns, except the last, an "index"(I) code is recorded since the index codes, unlike the carrier return codes, will not cause the card transport to step to another track. Thus on a single track there could be a code sequence of I,I,I,CR. The printer in an MC/ST system will, however, honor each index code and carrier return code and advance a line for each one read, even though the sequence of codes is recorded on a single track of the magnetic card.

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Correcting Line To Track Correspondence

To conserve tracks on a magnetic card in an IBM Magnetic Card "SELECTRIC" Typewriter (MC/ST) it is the usual practice with "white space" on a page, such as occurs between the internal address and the body of a letter, which requires a number of line advances, to not record a carrier return (CR) code for each line advance. Instead for all carrier returns, except the last, an "index"(I) code is recorded since the index codes, unlike the carrier return codes, will not cause the card transport to step to another track. Thus on a single track there could be a code sequence of I,I,I,CR. The printer in an MC/ST system will, however, honor each index code and carrier return code and advance a line for each one read, even though the sequence of codes is recorded on a single track of the magnetic card.

With this technique, if an operator on an MC/ST systems performs a track- step back, the line-to-track correspondence could be lost. Therefore, upon track- step back, the systems logic must cause each track to be read and the number of line advance codes (CR,1) read, and this count entered into a line-end counter and the platen on the printer reverse stepped once for each count as the counter is stepped down. The platen stepping operation ceases when the counter reaches zero.

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