Adding a 3rd floppy to an old PC SCSI controller

From: cclist at sydex.com To: cctalk at classiccmp.org Date: Mon, 31 Mar 2008 19:00:00 -0700 Subject: Adding a 3rd floppy to an old PC SCSI controller 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.