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Compatible Single Track Error Correction System

IP.com Disclosure Number: IPCOM000094821D
Original Publication Date: 1965-Jun-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 24K

Publishing Venue

IBM

Related People

Childs, HE: AUTHOR [+2]

Abstract

The error correction system is for use in tape control units TCU's. The system enables record tapes having both longitudinal redundancy check (LRC) and cyclic redundancy check (CRC) characters, and tapes having LRC characters but no CRC characters, to be used interchangeably in TCU's. Such interchanging is in TCU's which are adapted for use with tapes having CRC characters and in TCU's which are not adapted for use with tapes having CRC characters.

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Compatible Single Track Error Correction System

The error correction system is for use in tape control units TCU's. The system enables record tapes having both longitudinal redundancy check (LRC) and cyclic redundancy check (CRC) characters, and tapes having LRC characters but no CRC characters, to be used interchangeably in TCU's. Such interchanging is in TCU's which are adapted for use with tapes having CRC characters and in TCU's which are not adapted for use with tapes having CRC characters.

Here, the term old TCU refers to a TCU that is adapted to respond to LRC characters but not to CRC characters. New TCU refers to a TCU that is responsive to both LRC and CRC characters. Old tape refers to tape having LRC characters but not CRC characters. New tape refers to tape containing both LRC and CRC characters. It is assumed here that new tape is arranged in such a fashion that each CRC character follows an LRC character, as shown. A CRC character can be all zeros in some instances.

Compatibility requires, first, that when old tape is used in a new TCU, the TCU must not respond to the absence of a CRC character in the old tape as it would to the presence of an all-zero CRC character in a new tape. Second, when new tape is used in an old TCU, the CRC characters in the new tape must not be treated as though they are LRC characters in an old tape. Third, the implementation of the foregoing objectives must not render new tapes unusable in new TCU's or old tapes unusabl...