Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!utgpu!water!watmath!clyde!cbosgd!ihnp4!ptsfa!ames!ucbcad!ucbvax!YALE.ARPA!fischer-michael From: fischer-michael@YALE.ARPA.UUCP Newsgroups: comp.sys.atari.st Subject: Lost disk sectors Message-ID: <8707071803.AA02575@yale-eli.arpa> Date: Tue, 7-Jul-87 14:03:57 EDT Article-I.D.: yale-eli.8707071803.AA02575 Posted: Tue Jul 7 14:03:57 1987 Date-Received: Thu, 9-Jul-87 06:31:44 EDT Sender: daemon@ucbvax.BERKELEY.EDU Distribution: world Organization: The ARPA Internet Lines: 21 I wrote a little program to display the FAT (File Allocation Table) on a disk that appeared to be completely full and was surprised to see the last two clusters (= 4 sectors) free. Looking at the data itself confirmed that they were unused. Doing a little arithmetic, I came up with the following: When formatting a SS disk, TOS announces 357376 bytes free. Floppy disk space is allocated in clusters of 2 sectors = 1024 bytes, so 357376 bytes = 349 clusters = 698 sectors. Add to that 1 for the boot sector, 5 for each of the 2 copies of the FAT, and 7 for the root directory, and you get a total of 716 sectors. A standard format disk has 80 tracks times 9 sectors per track for a total of 720 sectors, so indeed there is a discrepency of 4. Similar results apply to a DS disk: TOS announces 726016 bytes free = 709 clusters = 1418 sectors. Add to it the 18 sectors at the beginning to get 1436 sectors, 4 less that the 1440 on a raw disk. Has anybody else noticed this before? Is it a TOS bug? If so, has it been fixed in the newer ROMs? --Mike Fischer-------