View Full Version : Cumulus 5.25" External Floppy Drive

February 16th, 2009, 02:56 PM
This is connected to the two previous messages I left below.

I have an external 5.25" tape drive made by Cumulus Corp. But I don't have the fdd ISA controller for it. Forgive my lack of knowledge here. I am referring to the plug one plugs the other end of the cable into. I bough this a few years ago, and I don't remember who on ebay I bought it from. I have been able to determine that the drive is a 1.2mb, and is an IBM compatible device.

My question is this. For some reason, I thought that I would be able to just plug it into the printer port, and that would be all.

But it's a 37 pin (pin, not edge) connector. I have the cable. It has a male plug on each end, and a female plug on the device, as well as whatever it plugs into.

I don't know if this is a scsi device or not.

I have found a 37 pin scsi fdd isa board, which has the correct type of connector on tyhe end. I also can buy a similar, but supposedly no scsi board made by IBM. My concern is this.

Does anyone have any experience with these drives? Does anyone know if these drives are proprietary, or can I use anyones fdd? If it is proprietary any idea where I can buy the right board?

February 16th, 2009, 03:50 PM
The Cumulus external drive was an odd bird. It does come with a controller card (of sorts; bear with me on this one), as well as a cable.

The "controller" is an ISA card with a DC-37 female connector on the bracket--and a couple of 34-pin headers internally. One 34-pin header was jumpered to your current floppy controller and the other, to your current floppy drives. That is, the "controller" is placed inline between your current controller and drives.

The reason I've been putting "controller" in quotes is that the Cumulus card is not a controller at all, but rather a switch that takes the existing floppy drive signals and, under software control, switches them to an external drive (or drives). You also added two more lines to your config.sys file--one for a driver.sys for the added drive and another, cufloppy.sys for the "controller".

The "controller" also supplied power to the floppy over the DC-37 cable, which is something that most floppy controllers can't do. However, I seem to recall that a Micro Solutions CompatiCard IV could be used to handle a Cumulus drive, as it did have jumpers for power distribution over the external drive connector. Good luck in finding one.

Hope this answers your questions.

February 16th, 2009, 06:03 PM
Hi! I have one of those cumulus external floppy drives and it uses a weird interface just like Chuck describes. I have considered making a kludged adapter to make the drive workable again but just never gotten to it.

Does anyone have the pinouts of the 37 pin DIN connector to interface the drive? As I recall its just a 34 pin edge to 37 pin DIN with a power connector.

Thanks and have a nice day!

Andrew Lynch

February 16th, 2009, 07:07 PM
I've got some notes I took years ago and I think they're for the Cumulus, but I'm not 100% certain.

(edge connector->DC-37):

2 -> 3 (Density select)
8 -> 6 (Index)
10 -> 7 (Motor enable 0)
12 -> 8 (Drive select 1)
14 -> 9 (Drive select 0)
16 -> 10 (Motor enable 1)
18 -> 11 (Direction)
20 -> 12 (Step)
22 -> 13 (Write Data)
24 -> 14 (Write Gate)
26 -> 15 (Track 0)
28 -> 16 (Write protect)
30 -> 17 (Read data)
32 -> 18 (Head select)
34 -> 19 (Disk changed)
+12 on pin 1
+5 on either 4 or 2
odd -> 20-37 (Ground)

You could just pop open the drive box and buzz it out, since there's nothing more than a garden-variety Epson 1.2MB drive in there.

February 17th, 2009, 02:38 AM
Hi Chuck! Yes, I have considered just using the VOM to map out the circuit since it *appears* to be pretty straight forward. Its just a matter of time since I don't need the drive right now. Still it would be nice to move this off the "to do" pile and into something useful.

Thanks and have a nice day!

Andrew Lynch