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From: dj@ctron.com (DJ Delorie)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: Re: Simple floppy question
Message-ID: <1508@balrog.ctron.com>
Date: 17 May 91 18:44:56 GMT
References: <1991May17.152846.21839@magnus.acs.ohio-state.edu>
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In article <1991May17.152846.21839@magnus.acs.ohio-state.edu>, skesterk@magnus.acs.ohio-state.edu (Shane Kesterke) writes:
> Here's a simple question that I've never gotten a straight answer on
> in all the time I've been exposed to computers. When a floppy drive accesses
> the disk the budy light always stays on for about 2 seconds after it's
> done accessing. Is it safe to pull the disk out during this time or is
> it better just to wait till the busy light turns off?

Traditionally, this delay is a sort of "motor-on cache" in case
you access the disk within a short period.  It prevents having
to wait for the disk motor to spin up each time you access the
floppy.  The BIOS simply sets a timer and shuts off the motor
after a few seconds of inactivity.

This implies that, once you get the command prompt back it's
safe to remove the floppy, since the program has obviously
finished writing to the diskette.

HOWEVER, if you are running a disk cache program that does
I/O in the background (you never can tell, either) it might just
still be writing to the diskette.  So if you have a disk cache
and you don't know for sure if it does this, don't take the
chance.

DISCLAIMER:  If you don't understand this explanation, don't
remove the floppy until the light goes out.  Same for your hard
drive.

DJ
dj@ctron.com