View Full Version : Kaypro 360 KB Floppy Drives in a Modern PC

May 3rd, 2013, 11:44 AM
I pulled two 5.25 floppy drives out of a Kaypro 1 and I'm trying to get them set up on a modern PC.

In the Kaypro, the second drive (drive B) has the terminator resistor pack installed, but I've read in a couple of places that the PC requires that pack to be removed, if 2 drives are going to be used in a system. Does anyone know if this is correct?

My specific setup (PC):
motherboard supports two legacy floppy drives (in the BIOS) of type 360 KB, 5.25 inch
motherboard has a floppy connector
"twisted" type floppy ribbon cable
drive A is installed on the end of the cable, drive select jumper = position 2 (on these drives, that's DS1)
drive B is installed on the middle of the cable, drive select = position 2 also

They appear to be working correctly, at least in terms of the led lighting up, boot sequence, etc- except for two things:
1. the drive motor is constantly on, even when the drive door is open (the led is not on however at that point)
2. I haven't been able to successfully format at 360 KB disk yet

May 3rd, 2013, 01:10 PM
Turn the system on, but leave one drive's signal cable disconnected. Does the motor still spin? If not, it's time we went back and looked at the cable setup.

May 3rd, 2013, 01:42 PM
Terminator or no, both should be DS1, and if you get the motor spinning with the data cable connected but not with it disconnected (but still power connected, like Chuck mentions above), then you're plugging the data cable in backwards (stripe on the wrong side).

May 3rd, 2013, 01:53 PM
I'm a little hazy on this but... I seem to recall that the Kaypro uses specific drive identification and the PC uses the twisted cable to change the ID. So I think that both drives in the PC need to be drive 1. The resistor should be on one of the drives the last I believe.

May 3rd, 2013, 02:38 PM
There's only one "motor enable" line on the standard SA450 interface, hence the reason for the twist on the PC cable--said twist also allows differentiation of two drives both set to the second drive select.

If the test with the cable removed shows the same behavior, try installing about a 2K resistor between that drive's pin 16 and +5 as a pullup.

May 3rd, 2013, 08:08 PM
Ok I ran that test of unplugging the data cable and found that the drive is still constantly spinning.

Also, I was able to fix the setup so that I could successfully format a 360 K floppy (using 22DSK in DOS):
Disk 1 is set to DS1, terminator pack installed, attached to the last data connector on the ribbon cable (this is drive "A")
Disk 2 is also set to DS1, NO terminator pack installed, attached to the middle data connector (this is drive "B")
As far as the ribbon cable connectors go, I made sure the red stripped wire lined up with Pin 1 on both drives and the motherboard connectors.
BIOS still has both drives configured as 5.25 inch 360 K drives

Does the drive always spinning mean something is still not setup correctly? If it still spins with no data cable, must be a jumper on either the drive or the motherboard, correct?

If it helps, these are both Panasonic JU-455-5 AAG drives (half-height).

Thanks for the help.

May 3rd, 2013, 09:34 PM
Try moving the terminator from one drive to the other and see if the motor issue moves to the other drive. If so, then you need only a pullup resistor on the spinning drive (can probably just be stuck into two pins on the terminator socket).

May 5th, 2013, 07:00 AM
Try moving the terminator from one drive to the other and see if the motor issue moves to the other drive.

Moving the terminator to the other drive didn't solve the problem, but made me realize the motor is spinning in both drives all the time, regardless if they have the data cables in or out.

But, I also found out some more info that may help:

I think these Panasonic JU-455-5 AAG drives may actually be "quad-density" drives. I used the 22DSK program to format some blank floppies I have and found that it was capable of formatting a 96 TPI floppy in an 80-track configuration ("kay3" format for those familiar with that program). In short, I'm able to format floppies in both 40-track 48 TPI CP/M format, as well as 80-track 96 TPI CP/M format.

I also noticed that the flat ribbon cable that was used in the Kaypro 1 (the machine I pulled these drives out of) has one pin blocked out on the motherboard connector which prevented me from using the same cable in the PC setup. Forgive my ignorance on this, but looking at the cable head on, pin 1 on the left, it is the third hole from the left, bottom row. So maybe these drives use a totally different pin/signal configuration that the PC can't support.

Another complicating factor, the BIOS in the PC only supports two 5.25 drive types: 360 K and 1.2 M. But when I configure it to 1.2 M, the boot-up fails on a floppy drive failure message.

So maybe I should back up and find some true 360 K drives to put into this PC, since the BIOS seems to support that and that's really the only drive type I need for what I'm trying to do.

May 5th, 2013, 09:18 AM
So it's probably a matter of getting the drive jumpered correctly.

About all you can really do with a QD (720K) 5.25" drive is configure it as a 3.5" drive on a PC. The format will be unreadable by any standard 5.25" PC setup, however. You could use a driver on a 1.2M drive to handle the format if push came to shove.

I did this for a time when I first had my 5150. I replaced the SS "160K" drive with a double-sided "360K" drive and added a second QD (720K) drive. It was valuable in that on a floppy-only machine, you could get 2 drives' worth of data on a single floppy (I still have some of those diskettes). When I got my first hard drive, this all became academic.