🚀 go-pugleaf

rob@kaa.eng.ohio-state.edu (Rob Carriere) writes:
>It takes a digital circuit at most a couple of hundred
>microseconds to complete any power-up state races.

This is true enough (usually), but if the design is bad, the result
might be a state you do not want - such as read/write flipflops being in
the "write" state.  NOTE: I don't say this happens, and it would be
pretty bad design if it did, but it IS possible.

>hard disk or a 5.25 floppy, the rw heads are removed from the media by
>means of a spring.  This effect has to be overcome before anything can
>happen; this a mechanical phenomenon, it will take milliseconds.  In
>the case of the 3.5 floppy, this device first has to slide open the
>door on the disk before it can even start to think about lowering the
>heads onto the media.  If you listen during power-up, you will notice
>that there is a pause of about a second before the disk door slides
>open.

Not on any 3.5" diskette drive I've ever seen.  The shutter opens when
you put the diskette into the drive.  The mechanism is purely
mechanical,  and has nothing to do with the power.  Similarly, a 5.25"
drive might possibly have a solenoid to lift the heads when power is
removed, but most drives either do not (the heads are in contact with
the media whenever the disk is fully inserted and the lever thrown) or
have had the solenoid disabled - the "clack-clack-clack" of the solenoid
is generally enough to drive you batty real quickly.

What sort of drives do you have, that you can hear this delay?

>In summary, by the time the rw heads get to the point where they could
>do damage, the control circuitry has long since settled down.  If
>there are problems, this reflects either a design error in the hard_
>and or software, or a transient glitch.

Hmm. "Transient glitch".  Like, the transient glitches that you get all
through your system when the power comes up or goes down?  You do as you
will.  I'll continue to take the diskettes out before I power up or down,
thank you.

-- 
Michael J. Farren             | "INVESTIGATE your point of view, don't just 
{ucbvax, uunet, hoptoad}!     | dogmatize it!  Reflect on it and re-evaluate
        unisoft!gethen!farren | it.  You may want to change your mind someday."
gethen!farren@lll-winken.llnl.gov ----- Tom Reingold, from alt.flame