Adding a 3rd floppy to an old PC SCSI controller

[Chuck Guzis]

The other day, I noted that both the DTC 3280 and the UltraStor 14N 
SCSI controllers have an option to add a 3rd floppy drive to the 
common floppy cable.  Essentially, they place the motor control on 
pin 4 and drive select on pin 6 for the extra drive.  It's not hard 
to make up a cable (Ultrastor supplied one with their kits) and a 
simple DOS driver provides access to the third diskette.  I have a 
couple of drivers, if anyone's interested.

But I wanted to use a Future Domain 1670 controller in this case.  It 
uses the same FDC (National DP8473), but doesn't bring the motor and 
drive select out to the floppy connector.  So, for 5 minutes of time, 
and a couple of lengths of wire wrap wire and a hot soldering iron, 
all one need do is strap pin 4 of the floppy connect to pin 1 of the 
8473 and pin 6 of the floppy connector to pin 42 of the 8473.  

Works great.  Wish I would have thought of this trick when the 
controller was new 15 years ago.  

Cheers,
Chuck