Adding a 3rd floppy to an old PC SCSI controller

[dwight elvey]

> 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.
>
>

Hi Chuck
 Pardon me for asking but are you sure the chip can provide
enough drive? Most floppies expect to terminal with about
150 Ohms. That is more than an unbuffered output of most
chips are designed for.
 Just asking?
Dwight

_________________________________________________________________
Windows Live Hotmail is giving away Zunes.
http://www.windowslive-hotmail.com/ZuneADay/?locale=en-US&ocid=TXT_TAGLM_Mobile_Zune_V3