Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!purdue!ames!vsi1!octopus!pete From: pete@Octopus.COM (Pete Holzmann) Newsgroups: comp.binaries.ibm.pc.d Subject: Re: High density disk drive & Low density diskette Summary: Can't be guaranteed. Message-ID: <1989Aug27.020118.19854@Octopus.COM> Date: 27 Aug 89 02:01:18 GMT References: <2734.24F37377@isishq.FIDONET.ORG> <1009@key.COM> Reply-To: pete@octopus.UUCP (Pete Holzmann) Distribution: usa Organization: Octopus Enterprises, Cupertino CA Lines: 56 In article <1009@key.COM> perry@arkon.key.COM (Perry The Cynic) writes: >In article <2734.24F37377@isishq.FIDONET.ORG> Kim.Tan@p1004.f162.n221.z1.FIDONET.ORG (Kim Tan) writes: >> The saleman in one of the computer store told me that I can read and >>write a low density diskette (360K) on a high density disk drive (1.2M) as >>long as I formated the 360K diskette on a low density disk drive. After >>using the high density drive on a low density diskette, I can still use a >>low density disk drive to read off the data without any problem?!? > >Amazing! A salesman who actually knows what he's talking about! :-) Nope. It will *usually* work, on *most* drives. >Yes, that's quite right. Formatting lays down the tracks and sector markers >on your floppy. Once it's formatted, reading and writing follows those markers. >The tracks put down by the high-density drive hardware are thinner (after all, >it's got to be able to put more of them onto a disk!), and thus there's a >danger that a low-density drive won't be able to recognize them. On the other >hand, just reading and writing shouldn't be a problem. Nope. Formatting lays down both the sector markers *AND* null data between the sectors (this is NOT the same as hi-level-DOS-formatting a hard disk, which doesn't really format the disk at all). Writing to the 360K disk will place a thin track down the middle of the pre-formatted 360K data. Formatting and writing both on the 1.2 drive is usually better, but even then, the thin track sometimes can't be read on the 360K drive. >It's mostly a question of safety >margins; if your drive has marginal alignment in one direction, and the other >drive is marginal in the other, you may have problems. Nope. I did some extensive experiments last year. Got some (rather expensive) high quality drive alignment gear, aligned a bunch of drives within an inch of their life :-), and went at it. I even picked up a copy of the software package that is supposed to make writing to 360 on 1.2 100% reliable. Sorry, but while it works most of the time, on most drives, you just can't count on it working in a crunch. >Thus, once you tried >that on two given drives and it works, you're probably pretty safe. You just >shouldn't make a LD floppy on a HD drive, and send it off to be used on any >old LD drive. YUP! You also shouldn't expect it to be used on any old HD drive either. Not even on the SAME HD drive. You just can't *depend* on it working. But in an office situation, where you could easily try again if it didn't work, you'll be in good shape! Perry, thanks for sharing from your experiences, in any case! Pete -- Peter Holzmann, Octopus Enterprises |(if you're a techie Christian & are 19611 La Mar Ct., Cupertino, CA 95014 |interested in helping w/ the Great UUCP: {hpda,pyramid}!octopus!pete |Commission, email dsa-contact@octopus) DSA office ans mach=408/996-7746;Work (SLP) voice=408/985-7400,FAX=408/985-0859