Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.csd.uwm.edu!cs.utexas.edu!uunet!yale!root From: root@yale.UUCP (Root Of All Evil) Newsgroups: comp.sys.atari.st Subject: Re: floppy disk sizes, how to calculate them Keywords: atari st, c Message-ID: <71002@yale-celray.yale.UUCP> Date: 29 Aug 89 20:33:03 GMT References: <4552164d.14a1f@force.UUCP> Reply-To: fischer-michael@CS.YALE.EDU (Michael Fischer) Organization: Yale University Computer Science Dept, New Haven CT 06520-2158 Lines: 29 In article <4552164d.14a1f@force.UUCP> covertr@force.UUCP (Richard E. Covert) writes: > >... > >I am writing a backup program and I need to ask the user for the >size of his floppy. There are many ways of doing this. One method is for >the user to enter the decimal number of bytes per floppy (from a table >shown on the screen). another way is to ask the user to enter the number of >tracks per disk, number of sectors per track, and number of sides per disk. >I perfer the latter. This information is all available in the boot sector. You just need to know where to look for it. It's the same as for MS-DOS, so you can look in Norton's book on the IBM-PC to learn how disks are structured. > But, how do I calculate the amount of usable space based on the >number of sectors, tracks, and sides?? Some of the disk is used by the >directory, and I heard that there are some unused sectors at the end. >So, what is a good formula for determining the size of a floppy?? Why do you want to? The Gemdos call "Dfree" tells you how much space is left. It's only if you want to bypass Gemdos and write to the sectors directly through Bios calls that you need to worry about such things. ================================================== | Michael Fischer | | Arpanet: | | Bitnet: | | UUCP: | ==================================================