Crazy question about floppy drive compatibility

[rglenn]

Could an external floppy drive designed for an S100 system with a 50 pin connector be made to work on an IBM PC?

 

[Chuck(G)]

I assume that you mean an 8" drive? The answer is yes. Easiest using one of the dBit boards.
However, be aware that a lot of 8" disks were recorded using FM. Your PC's disk controller may not be able to handle that.

 

[NeXT]

[Gets sniped by Chuck(G)]

You mean like the Shugart 8" floppy drives?
Absolutely! There's already adapters that exist for this reason.

 

[rglenn]

Thanks everyone. I was looking at a Thinker Toys 8" drive.

 

[Nama]

I've previously had 8" drives hooked up to my 486 to do some floppy backups with IMD

 

[rglenn]

Ok, so before I drive myself nuts, any thoughts on what I'll need to actually connect the drive to the PC?
The PC (5150) has an external DB37 female connector from the floppy controller
The external 8" drive has an external 50 pin male ribbon cable connector (at least that's what I think it is) picture attached
It sounds like I'm going to need something like this as well (picture attached) - https://www.ebay.com/itm/115729590176?var=415793651897

Any thoughts would be appreciated.

 

[Chuck(G)]

Start here

 

[rglenn]

Update - I now have the drive set up with a 37 pin to 50 pin adapter. The drive light is on and using the IMD program, the RPM test runs. When I use either IMD of 8FORMAT to format the disk, I get a write protect error. The 8" disks I am using are not notched, Additionally, with 8FORMAT I get the following error codes - !ST0 0x40 and !ST1 0X2. Any ideas?

 

[Chuck(G)]

Have you probed pin 44 on the drive interface to see if the drive is actually asserting the signal?

 

[rglenn]

I have not. I recently ordered a logic probe but have never used one. I removed the drive from its enclosure and I'm assuming you mean pin 41 on the ribbon connector. I have additional information that may shed new light on the issue, if not I can try to figure out how to probe pin 41. New info - the drive is a Shugart 800-2. The 4 termination jumpers are in place (T3-T6) Drive select jumper is on DS1. I am connecting from an on-board floppy controller on a P4 system connected to a 37 to 50 pin adapter. The A drive is set to 5 1/4 1.2 in the BIOS. The disk is spinning continually when the drive is on. Using IMD, the clean head routine appears to be working on screen but the drive head never moves. All attempts to format result in a write protect error.

 

[Chuck(G)]

No, I mean pin 44 on the drive connector:

Floppy drive pinout

The floppy drive pinout varies between computer types, though many are very similar. Here are the pinouts for various retro computers.

dfarq.homeip.net

 

[Chuck(G)]

You don't need a logic probe. A DMM will do fine--this isn't a fast-moving signal.

 

[rglenn]

Thanks. I'm almost there. I have the Shugart setup as drive B. On boot, it lights up and the head moves as expected and then the light goes out. In IMD, the head clean process now does move the head as expected. When I try to format a disk, the head moves across the disk and back to stop position like it's going to start formatting the disk and then I get either a "no interrupt from FDC" or "Floppy drive controller failed to respond in time IRQ 6 timeout" depending on which program I use.

 

[rglenn]

I'm using a PTI-205 XT/AT 8 bit FDD Controller.

 

[Chuck(G)]

Check that you're getting a good index pulse from the drive. Also try formatting it using FORMAT.COM declaring the drive as 1.2MB and high density (formatting it as a 1.2MB drive). You are using soft-sectored media, aren't you? Do you hear the head-load solenoid click in?

 

[rglenn]

Working now. Thank you.