Kim.Tan@p1004.f162.n221.z1.FIDONET.ORG (Kim Tan) (08/24/89)
Hi There!
I have a question about the IBM PC low density diskette (360K) and a high density disk drive (1.2M).
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?!?
Can someone tell me whether it is true or not. Thanks for your help.
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Kim Tan KaTan@CGRVAX.Uwaterloo.Ca
Waterloo Centre for Groundwater | FidoNet : 1:221/162.1004
Research | InterNet : Kim_Tan@isishq.watmath
University of Waterloo | BitNet : Lrsdan@Vm.UoGuelph.Ca
Waterloo, Ontario | Uucp : ..!watmath!isishq!Kim.Tan
N2L 3G1 | ..!watmta!cgrvax!KaTan
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Kim Tan - via FidoNet node 1:221/162
UUCP: ...!watmath!isishq!162.1004!Kim.Tan
Internet: Kim.Tan@p1004.f162.n221.z1.FIDONET.ORGsimcha@kurz-ai.UUCP (Simcha Lerner) (08/25/89)
The problem with taking a 360KB diskette that has been written on a
1.2MB drive to a 360KB drive has to do with the different track
widths that the two drives' heads write. In essence, the 1.2 MB drive
leaves a border of unwritten media on either side of the track, which
the 360KB drive will end up reading.
My experience is that the best way to achieve reliable interchange is
to start with a never before used diskette, and only format and write
to it with one type of drive. This will give 98+% odds that the other
type of drive will be able to read it.
The ability of the 1.2MB drive to read a diskette written in a 360KB
drive is obvious, since it ends up reading the center of a track
wider than its head gap. The reason the 360KB drive can reliably read
a disk that was written on the 1.2MB is due to the border being
unformatted. Unformatted media has an average flux that cancels
itself out, allowing the flux of the narrow track that was written to
dominate.
If a diskette has been formatted or written by a 360KB drive, the
border will have flux values that contain data. Since the 1.2MB drive
leaves a border of this old data when it overwrites it, there is a
finite chance that this will cause read errors when returned to a
360KB drive with its wider head gap.
In any case, my personal practice is to NEVER write _critical_ data
on a 360KB disk in a 1.2MB drive if I am going to need to read it on
a 360KB drive. I get a 360KB drive installed instead.
--
Simcha Lerner
Kurzweil Applied Intelligence
PLEASE NOTE ADDRESS: NO RETURN MAIL VIA bbn PLEASE
UUCP address: kurz-ai!simcha@talcott.harvard.edu
or: ...{uunet,rutgers,ames}!harvard!talcott!kurz-ai!simchaperry@key.COM (Perry The Cynic) (08/25/89)
In article <2734.24F37377@isishq.FIDONET.ORG> Kim.Tan@p1004.f162.n221.z1.FIDONET.ORG (Kim Tan) writes: > I have a question about the IBM PC low density diskette (360K) and a high density disk drive (1.2M). > 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! :-) 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. That's the theory, anyway. In practice, I have repeatedly formatted low-density floppies on my high-density drive (in 360K format, of course), and used the resulting disk on XTs without problems. 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. 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. I hope that clears things up. -- perry -- ------------------------------------------------------------------------ Perry The Cynic (Peter Kiehtreiber) perry@arkon.key.com ** What good signature isn't taken yet? ** ...!pacbell!key!perry
usenet@cps3xx.UUCP (Usenet file owner) (08/27/89)
In article Kim.Tan@p1004.f162.n221.z1.FIDONET.ORG (Kim Tan) writes: > I have a question about the IBM PC low density diskette (360K) and > a high density disk drive (1.2M). Please use lines that are less than 72 (or at worst 80) characters long. The width of the track on 1.2M 5.25" floppies is much narrower than the width of the track on 360K floppies. Hence, you may have problems with noise if you format a disk on a high density drive, and then try to use it in the future on a low density drive. Likewise, if you write a file with a high density drive, you may experience noise problems reading it on a low density drive. Note that the key word is MAY. Note I always mean formatting in the low density format, even on high density drives. The newer technology is UPWARD compatible, but not necessarily DOWNWARD compatible. Hope that helps. In the rare case that original ideas Kenneth J. Hendrickson N8DGN are found here, I am responsible. Owen W328, E. Lansing, MI 48825 Internet: hendrick@frith.egr.msu.edu UUCP: ...!frith!hendrick
pete@Octopus.COM (Pete Holzmann) (08/27/89)
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