Date   : Sat, 23 Feb 1991 10:53:27 PST
From   : sprague.wbst311@xerox.com
Subject: Motor on and Drive Select

I stand corrected.  The manual for the SA 455/465 says that is does indeed have
a READY signal.  In additon, the manual states that it takes 500 mS for the
drive motor to come up to speed.  READY becomes active 700 mS after the MOTOR
ON signal is generated (assuming all other signals are correct).  It stands to
reason that modern drives are at least as fast as the older SA 455/465, but
still a delay of 500 to 700 mS is in order, just to play it safe.

Better yet if I can use the drives READY signal.  Turns out that it's the 5.25"
READY signal I understand, not the 8".  I poked around with a logic probe this
morning, but didn't find anything out.  I suspect I'll need to have the drive
in a working system, with Drive Select active to find anything out.  I'll let
you all know what I find out.

Last, I think I found the jumper to connect Motor On with Drive Select on the
Chinon drives.  On the 360kb drive (which you can get for $49), you need to
remove the metal shield, and solder a jumper (no jumper pins here) onto J4.  It
is labeled on the circuit board, and has a box around it.  I know have a pair
of them running on my Xerox 820-II.

On the Chinon 1.2Mb drives ($59) I found one of the jumper blocks to be labeled
MS.  As the pins are jumpered together, I assume that if the jumper is
unplugged, then Drive Select and Motor On will be tied together.  I have yet to
test this out though.

I am interested in hearing more from those of you who have or are trying to
replace 8" drives with 3.5" drives.

Enjoy!

                               ~ Mike  (Sprague.Wbst311@Xerox.Com)