Date   : Wed, 27 Feb 1991 07:17:10 PST
From   : sprague.wbst311@xerox.com
Subject: Floppy drives and MOTOR ON

Earlier I wrote:

> 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 tested it, and it isn't.

Upon taking the metal shield cover off, I discovered that the jumper was MS1
not MS.  There was also a jumper for MS2.  From this I assume that the jumpers
are really for setting the disk speed either to single speed (MS1) our dual
speed (MS2).

I attempted to follow the MOTOR ON trace on the circuit board (which is how I
found the correct jumper on the 360K drives), but had no luck in finding any
jumper to set the MOTOR ON signal to the DRIVE SELECT signal.  Ah well, back to
the AND gate solution.

I did tie MOTOR ON to ground.  As expected, the motors spun all the time, and
the head stayed loaded.  In additon, I set the jumper that selects between Disk
Ready and Disk Change to the Disk Ready setting.  I connected pin 36 (now Disk
Ready) to the READY line on the 8" interface, and it seemed to work fine.
However I do not know if this will work under normal operation when the motor
has to spin up.

                               ~ Mike  (Sprague.Wbst311@Xerox.Com)