Aucbvax.4055 fa.unix-wizards utzoo!decvax!ucbvax!unix-wizards Sat Sep 26 00:03:31 1981 RM80 skip sectoring >From decvax!shannon@Berkeley Fri Sep 25 23:49:01 1981 In response to sdyer@bbn-unix's question: The skip sector feature was added to the RM80 because they expected to have disks with more bad spots on them than can be handled by DEC STD 144. The skip sector feature allows the first bad spot on each track to have a replacement sector at the end of the track. Very little of the skip sector feature is automatic. The read or write will abort when it runs into a sector with the skip sector bit set. The device driver must then set the "skip sector error inhibit" bit and continue the transfer at the next sector. The first bad sector on each track, and all subsequent sectors on that track, will be marked with the skip sector bit. The skip sector error inhibit bit suppresses the interrupt when a skip sector bit is encountered on a sector. It also allows you to access the extra sector at the end of the track, which is otherwise not used. If a track has more than one bad sector, all but the first will be marked with BSE's (bad sector errors) and must be handled by some other mechanism (e.g., DEC STD 144). The 4.1bsd bad block handling (which I wrote) handles all of this transparently on all types of transfers. Bill Shannon decvax!shannon or CSVAX.shannon@Berkeley ----------------------------------------------------------------- gopher://quux.org/ conversion by John Goerzen of http://communication.ucsd.edu/A-News/ This Usenet Oldnews Archive article may be copied and distributed freely, provided: 1. There is no money collected for the text(s) of the articles. 2. The following notice remains appended to each copy: The Usenet Oldnews Archive: Compilation Copyright (C) 1981, 1996 Bruce Jones, Henry Spencer, David Wiseman.