Using a 1.44MB 3.5inch floppy on an old controller

From: Michael Brutman <mbbrutman_at_chartermi.net>
Date: Sun Apr 22 11:42:15 2001

I have a few PCjrs running around, and I've often thought of
either adding 3.5" drives to them, or replacing the standard
5.25" drive with 3.5" drives. The controller only supports
double density data rates (250?), so I'm limited to 720KB
3.5" drives. These are getting hard to find.

I connected a new 1.44MB drive to the controller, and
behold, it worked! (With double density media of course.)
The machine booted from the diskette (which was created from
a 360kb image prepared on a Linux machine), and it also ran
diagnostics. So now I'm confused - why did it work?

Does the modern 1.44MB drive sense that the controller is
only sending data at 250KHz rate? If so, how is it doing
the sensing? (The reduced write-current pin (2) isn't
being used - I verified that with a meter.)

Thanks,
Mike
Received on Sun Apr 22 2001 - 11:42:15 BST