Path: utzoo!mnetor!uunet!mcvax!ukc!mupsy!liv-cs!unpowell From: unpowell@csvax.liv.ac.uk Newsgroups: comp.sys.atari.st Subject: Re: Atari Disk formats (Revisited) Message-ID: <531@csvax.liv.ac.uk> Date: 18 Apr 88 16:56:37 GMT References: <8803210013.AA22627@icase.arpa> <517@uhnix2.UUCP> Lines: 61 Organisation: Computer Science CSVAX (VAX1), Liverpool University In article <517@uhnix2.UUCP>, uace0@uhnix2.UUCP (Michael B. Vederman) writes: > In article <8803210013.AA22627@icase.arpa> csrobe@ICASE.ARPA (Charles S. Roberson) writes: >>I would like some help sorting out the available disk formats. I've used >>intelligent copy (I only have one disk drive while my HD is being repaired, >>again :-( )). The most significant thing about DCformat is that it allows >>you to format 82 tracks per disk. I also remember some people saying that >>certain drives won't let the r/w head go that far -- I think mine is one. >>Would some kind soul take the time to explain DCformat (especially when >>are the options (sectors per track, tracks, side, etc) active). If I >>am doing a disk copy, do these options have any effect? > etc.... >>+-------------------------------------------------------------------------+ >>|Chip Roberson ARPANET: csrobe@icase.arpa | Atari external drives can cope with 83 tracks. Early Atari internal drives can cope with 82 tracks. More recent internal models can only cope with 81 tracks. I don't know about the States, but in England, if you purchase a non-Atari external drive, such as Cumana or A,S&T it will generally be able to cope with 86 tracks (yes 86!). I definately know that A,S&T drives can cope with 86 tracks, as I own one. As to sectors per tracks. Any drive (any?) should be able to read and write 10 sectors per track. The number of drives that can handle 11 sectors per track is limited. My Atari external drive can read/write 11 sectors quite unhappily (it slows down file reading and writing). My A,S&T external drive, on the other hand, cannot handle 11 sectors per track. I've tried without little success to vary the sectors per cluster. I think this is always taken to be 2 by the ST. I've tried to vary the number of FAT tables without much success. I think the ST has to have 2 FAT tables per disk. (This is a good idea anyway. If you lose your, only, FAT table, you can forget your data). Sectors per FAT can be altered quite readily. You must calculate how many clusters you have on your disk, before setting the sectors/FAT. The Desktop formatter uses 5 sectors/FAT which is too many for any floppy. To calulate the number of sectors/FAT your format needs, perform the following calulation. RES=number of reserved sectors i.e 1 for the boot sector FAT=number of FAT tables DIR=number of directory entries. Usually $70, but is variable SEC=number of sectors on disk SPF=sectors per FAT SPF=INT(INT((SEC-INT((DIR+15)/16)-FAT*SPF)/2)+2*3/2)/512 Simple really. Mark Powell. ******************************************************************************** "...there's no success JANET unpowell@uk.ac.lis.csvax like failure and UUCP {backbone}!mcvax!ukc!mupsy!lis-cs!unpowell failure's no success ARPA unpowell%csvax.lis.ac.uk@nss.cs.ucl.ac.uk at all..." B.Dylan ********************************************************************************