Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!cs.utexas.edu!uunet!philmtl!ray From: ray@philmtl.philips.ca (Raymond Dunn) Newsgroups: comp.sys.ibm.pc Subject: Re: 1.2meg/360k compatibility question Message-ID: <597@philmtl.philips.ca> Date: 12 Jul 89 00:36:32 GMT References: <2250@astroatc.UUCP> <15072@ut-emx.UUCP> Reply-To: ray@philmtl.philips.ca (Raymond Dunn) Organization: Philips Electronics Ltd. - St. Laurent P.Q., Canada Lines: 43 In article <15072@ut-emx.UUCP> nghiem@walt.cc.utexas.edu (Alex Nghiem) writes: >In article <2250@astroatc.UUCP> brown@astroatc.UUCP (Vidiot) writes: > >>First off the problem of writing 360K diskettes on a 1.2M drive is a real >>problem. The only way is to have both a 1.2M and a 360K drive. > >Not true. I've worked on a Compaq Portable III with a dual speed >1.2 that could format a 360K that can be read on a standard PC. >The problem I have is identifying who makes the drive. I know >that Teac, Toshiba, and Fujitsu make dual speed 1.2 megs. I >trying to find out which one works best. > >(Please send E-mail. I'll summarize and post to the net.) Please don't! As Mr. Brown says 1.2M/360K is a real problem. *ALL* 1.2Meg drives are "dual speed" to enable them to read and write both 1.2M and 360K diskettes. A 1.2M drive must have a head with a gap which is about half the width of a 360K drive. A diskette written at 360K density on a 1.2M drive has a track which is half the width of that written on a 360K drive. That is the cause of the problem. It could only be overcome by having a drive with two heads, one used when dealing with 360K diskettes, the other when dealing with 1.2M. There are no such drives to my knowledge. x times out of y you "get away" with writing at 360K on a 1.2M drive and reading it on a 360K drive. X and y vary enormously from drive to drive, diskette to diskette, and the *history* of the diskette (on which density drive it was formatted, what and where it was previously written etc). When 3.5" drives *first* came out there were several compatability problems drive to drive (even within 720K). These have now all but evaporated. -- Ray Dunn. | UUCP: ..!uunet!philmtl!ray Philips Electronics Ltd. | TEL : (514) 744-8200 Ext: 2347 600 Dr Frederik Philips Blvd | FAX : (514) 744-6455 St Laurent. Quebec. H4M 2S9 | TLX : 05-824090