Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!nrl-cmf!ukma!tut.cis.ohio-state.edu!ucbvax!hplabs!hpfcdc!hpislx!hplvli!boyne
From: boyne@hplvli.HP.COM (Art Boyne)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Are 720K floppies really 1.44M in disguise?
Message-ID: <360007@hplvli.HP.COM>
Date: 7 Feb 89 16:22:44 GMT
References: <1140@ccncsu.ColoState.EDU>
Organization: Loveland Inst. Div
Lines: 20

akm@uoregon.uoregon.edu (Anant Kartik Mithal) writes:

> Years ago, I used to format 5.25" SSDD as DSDD (180K as 360K) without
> any difficulty.
                         NEVER do this!!!! 
After prolonged abuse like this, the floppy drive can be *destroyed*.

     Single-sided disks are usually burnished/polished only on the single
recording side.  The other side is rougher, causing wear hardening of the
disk read/write head.  Wear hardening is a phenomenon where the material
of the head loses its magnetic properties, causing the effective read/write
gap on the head to back away from the surface of the head.  This increases
the effective distance from the gap to the surface, lowering the signal
levels and increasing the chance of error.  Eventually, enough damage will
be done that nothing can be reliably written or read.

     I learned this while working for the division of Hewlett-Packard that
made 8" and 5.25" floppy drives, and the same thing applies to the 3.5" units.

Art Boyne, boyne@hplvla.HP.COM