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Tapemark Format for Drive With No Tapemark Support

IP.com Disclosure Number: IPCOM000064173D
Original Publication Date: 1985-Jun-01
Included in the Prior Art Database: 2005-Feb-18

Publishing Venue

IBM

Related People

Authors:
Carter, DW Clegg, JA Martens, RD Wells, DK [+details]

Abstract

Tape files require tapemarks for distinguishing multiple files and also pieces of each file, that is, header labels, data, and trailer labels. This disclosure solves the problem of fixed-format tape drives which do not support tapemarks. With tapemarks available, it is easy to format files on a tape as done in the past. Tapemarks work as excellent delimiters for many different areas of the tape, such as Logical End of Tape and End of Volume, and for separating files. Since data blocks can vary in length between 18 and 32K-1 bytes, only two bytes of EBCDIC data are needed to define this length. Also, since we are looking for a data length, two bytes of X'FF' can be used as a delimiter (tapemark).