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Browse Prior Art Database

Tape Check Character Gating

IP.com Disclosure Number: IPCOM000097453D
Original Publication Date: 1962-Dec-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Brown, PJ: AUTHOR [+3]

Abstract

The section of magnetic tape 10 has a data block written on it. A check character is written immediately after the data block for checking the longitudinal redundancy of 1 bits in the respective rows in the block. After the check character, an interrecord gap follows prior to the start of any following data block. The interrecord gap normally is about three quarters of an inch.

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Tape Check Character Gating

The section of magnetic tape 10 has a data block written on it. A check character is written immediately after the data block for checking the longitudinal redundancy of 1 bits in the respective rows in the block. After the check character, an interrecord gap follows prior to the start of any following data block. The interrecord gap normally is about three quarters of an inch.

The check character is spaced farther from the last character of the data block than the interval between characters within the block. Often, the interval before the check character is five or six times the interval between data characters.

The end of the data block is detected by using a holdover type of delay device. This can be a holdover single-shot or a holdover counter. For example, the holdover counter can be reset by the start of each next character in a block. Thus, the counter can never exceed a particular count, such as 7, without being reset by a next character in the block. However, when the end of the block is reached, there is no next character to reset the counter before count 7. It consequently continues its counting sequence to its highest count 144, for example. The check character generally starts sometime after count 36 but before count 96, as shown by the pulses. As the bits of the check character are read they are registered in a sense register of a tape control.

Where a peak-detection system is used to sense pulses read from tape, any noise pulse riding on a 1 bit can make the one bit appear twice...