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82 column Check in Serial Card Readers

IP.com Disclosure Number: IPCOM000079173D
Original Publication Date: 1973-May-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Kornherr, H: AUTHOR [+2]

Abstract

By the use of a column counter and a test routine a check is made as to whether column-oriented record carriers, particularly punched cards, have been fully read in serial card readers. For each hole position in a column, one photodiode is provided which is hole-scanned four times per column position. The pulse generator emits sixteen pulses per column, four of which, disposed symmetrically to the ideal column center, serve to scan the photodiodes. After every sixteenth pulse the column counter is incremented by one.

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82 column Check in Serial Card Readers

By the use of a column counter and a test routine a check is made as to whether column-oriented record carriers, particularly punched cards, have been fully read in serial card readers. For each hole position in a column, one photodiode is provided which is hole-scanned four times per column position. The pulse generator emits sixteen pulses per column, four of which, disposed symmetrically to the ideal column center, serve to scan the photodiodes. After every sixteenth pulse the column counter is incremented by one.

The test determining whether all the column information has been read, is carried out in the second half of that column which is still fully accommodated by the card. This means all those columns are tested where only half or less than half of the succeeding column fits the card. To this end, the last scanning pulse D of the four scanning pulses is employed. If at least one of the photodiodes remains dark during testing, this indicates that the information has been read correctly.

Of a standard 80-column punch card the second half of the 82nd column is tested, for example. If during this test all photodiodes respond, this indicates that the card has passed the read station too rapidly and that the information in one of its columns has been lost. Suitably modified, this test routine, implemented by a microprogram, can be used for cards of different lengths.

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