Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.csd.uwm.edu!bionet!apple!amdahl!key!perry
From: perry@key.COM (Perry The Cynic)
Newsgroups: comp.binaries.ibm.pc.d
Subject: Re: High density disk drive & Low density diskette
Summary: All True.
Message-ID: <1009@key.COM>
Date: 25 Aug 89 00:04:57 GMT
References: <2734.24F37377@isishq.FIDONET.ORG>
Reply-To: perry@arkon.key.COM (Perry The Cynic)
Distribution: usa
Organization: Key Computer Laboratories, Fremont
Lines: 28

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