Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!usc!polyslo!jdudeck From: jdudeck@polyslo.CalPoly.EDU (John R. Dudeck) Newsgroups: comp.sys.ibm.pc Subject: Re: Formatting 1.2 Meg disks to 360K question Message-ID: <25ae5d02.42a2@polyslo.CalPoly.EDU> Date: 12 Jan 90 22:41:06 GMT References: <3226@ucrmath.UCR.EDU> <7715@nigel.udel.EDU> <25AD7F7A.26599@maccs.dcss.mcmaster.ca> Reply-To: jdudeck@polyslo.CalPoly.EDU (John R. Dudeck) Organization: Cal Poly State University -- San Luis Obispo Lines: 29 >In article jacobs@cs.utah.edu (Steven R. Jacobs) writes: >$On the high density disks, the >$oxide is a different material which requires a stronger magnetic >$field to record information. The heads in many 360K drives are >$not designed to produce a strong enough magnetic field to record >$data on the high density floppies. In article <25AD7F7A.26599@maccs.dcss.mcmaster.ca> cs4g6ag@maccs.dcss.mcmaster.ca (Stephen M. Dunn) writes: >And also, as I >understand it, it's actually the other way round. A 1.2M disk actually >uses a weaker magnetic field, which makes 360K disks written in a 1.2M >drive unreadable in many 360K drives. No, Mr. Jacobs is right, and Mr. Dunn is wrong. The high density diskettes have a higher coercivity, which means that they require a higher magnetizing field to record on them. Many older 360 k drives do not have the needed recording field for high density floppies. > If the problem was that 360K drive heads didn't generate strong enough >magnetic fields, then I should be able to format 1.2M floppies at 360K in >my 1.2M drive. Well, it doesn't work any better in that drive than it >does in my 360K drive. I don't understand this. I format high density diskettes to 360 k in my 1.2M drive all the time. However, if the floppy already had been written on, either as a 1.2 M disk, or as a 360 k disk on a 360 k drive, then the garbage in between the tracks sometimes makes the disk unreadable on a 360 k drive. -- John Dudeck "You want to read the code closely..." jdudeck@Polyslo.CalPoly.Edu -- C. Staley, in OS course, teaching ESL: 62013975 Tel: 805-545-9549 Tanenbaum's MINIX operating system.