Path: utzoo!attcan!uunet!husc6!bbn!uwmcsd1!ig!agate!ucbvax!hplabs!hp-pcd!hpcvlx!bill
From: bill@hpcvlx.HP.COM (Bill Frolik)
Newsgroups: comp.sys.ibm.pc
Subject: Re: formatting 3.5' disks
Message-ID: <101000002@hpcvlx.HP.COM>
Date: 7 Sep 88 16:32:43 GMT
References: <361@dcscg1.UUCP>
Organization: Hewlett-Packard Co., Corvallis, OR, USA
Lines: 20


Depends on the hardware.  If you're using an IBM PS/2 machine, the hardware
doesn't let software find out whether the hole is there or not, so the
format program just always assumes it's a 1.44M disk unless you specify
otherwise.  To format a 720K disk in the PS/2 1.44M drive, you have to
say FORMAT A: /N:9 (9 sectors per track instead of 18).  They even put
a warning in the User's Guide telling you not to format a 720K disk in
a 1.44M drive using FORMAT defaults, and not to format a 1.44M disk as
720K using the /N:9 switch.  What this gets you is flexibility; you can
use high density disks that don't have the extra hole.  It can also make
things confusing.

In HP's Vectra CS (and probably machines from other manufacturers, too)
the hardware senses the extra hole and the BIOS recognizes what type of
media is in the drive.  In that case, you just say FORMAT A:, and if you
have a 720K disk in the drive, you get 720K; a 1.44M disk gets you 1.44M.

-----------------------------------------
Bill Frolik		Hewlett-Packard
hplabs!hp-pcd!bill	Corvallis, Oregon