  Over the last several months I have received so much mail on our
SLEEP.EXE drive utility that I find myself typing the same thing around
10 times a day!  So I've taken the common things people are asking and
responded below.

  First a little background.  As notebook computers have become more and
more popular, disk drive manufacturers have responded by building power
management features into their drives.  That's right, if you have a
recent IDE drive odds are it already has the sleep capability built
right in!  All SLEEP.EXE does is send a command to the drive that says
"start your sleep feature."  The drive ITSELF does the timeout spindown
logic, turning itself off when the drive has not been accessed for the
specified time and starting itself back up when the drive is accessed.
SLEEP.EXE is not a TSR, since once it issues the command to the drive
the program is done.  

  True to form, some drive manufacturers interpret the sleep command
differently.  Some really do not care if their drives are used in
notebooks, and just ignore the sleep command.  You can tell these drives
by the fact that when you run SLEEP.EXE it seems to have no effect!
SLEEP.EXE will report that the sleep mode is not supported IF THE DRIVE
RETURNS AN ERROR on the command.  Unfortunately a few drives will return
that "everything is ok" with the command and then just ignore it.  In
this case SLEEP.EXE will report that the timeout is set, as the drive
lied to it!  The best way to tell if your drive supports sleep mode is
"does it work" -- easy enough to tell.  Most recent IDE drives have no
problems.

  You can now see why some drives spin down immediately when they get
the sleep command, and why some do not!  It's entirely up to how each
manufacturer decides to implement the feature.  You can also see why it
doesn't hurt to spin up and down your drive many times each day.  The
drive manufacturers have to make hard disks that stand up to the rigors
of notebook computing, so they have to design their drives to spin up
and down during the course of normal operation.  No manufacturer wants
to be known as the maker of a drive that wears out quickly when used in
a notebook computer!

  For those of you who would like a little more technical information,
the "sleep" command sent to the drive is 0xE2, and it takes a parameter
(0-255) that is the number of 5-second intervals to sleep.  We take
the number of minutes passed to SLEEP.EXE on the command line and multiply
it by 12 to get the parameter to send with the 0xE2.  You can see why
IDE drives do not support long timeouts, as (255*5)/60 is 21 minutes
and 15 seconds.  We chose a parameter that is 1 to 15 mintues to keep it
easy to remember.  And you guessed it, the fact that you cannot specify
a two hour timeout is a limitation of the drive itself!

  You can also see why it is impossible to harm your data by using
SLEEP.EXE.  Since it is not a TSR, nothing is resident to "mess up!"
Either the drive supports sleep and works or it ignores the command.

Since most drives go back to their default state on powerup, it is
necessary to run SLEEP.EXE each time you power up your computer.  This
explains why the sleep mode stays active when you CTRL-ALT-DELETE
or reset your computer (warm boot), since power is still applied to the
drive.

  We hope this helps everyone understand a little more of the wonderful
world of IDE drives, and power saving in general!  For the latest
version of SLEEP (1.20), just download SLEEP.ZIP from CompuServe,
America Online, or our own BBS at (816) 353-0991.  The new version has a
change that allows "SLEEP C 0" to turn off sleep mode without having to
power down your computer, and is worth the download.

  Dr. Boyd G. Gafford, EnQue Software
  Internet address:  DrBoyd@aol.com
