37 pin PC floppy interface for swapping 8" and 5.25" floppy drives?

[snuci]

Does anyone know if such a cable is available or if someone has a wiring diagram for it? Here's a pic on Dave Dunfield's site: http://www.classiccmp.org/dunfield/img54306/h/fcin.jpg

I would like to put this in a PC and swap between a 5.25" drive and a 8" drive, each with 37 pin connectors for my disk archiving machine. The 8" drive would go from 50 pin, through my FDADAP floppy interface then back to 34 pin for connection to the 37 pin male D sub connector. My 5.25" drive is an IBM 4869 external drive.

BTW, this, in turn, connects to my Adaptec AHA-1542 controller board so I don't use the original IBM floppy controller with the 37 pin connector already on board.

Any help is much appreciated.
Santo

 

[Chuck(G)]

Well, if you don't want to go the easy way and buy one of John Wilson's FDADAP adapters, here's appendix D3 from the Compaticard manual:

 

[snuci]

Hi Chuck,

I do have an FDADAP board already and use it. I'd just like to swap 5.25" and 8" drives as I use a portable (luggable) right now and would prefer to make the entire set up more portable. In fact, I recently acquired am IBM 9331-11 external 8" floppy drive. Not yet sure if it would work in this environment but I will have to wait until it arrives to check that.

 

[snuci]

Wow, I found a post from weasel some time back that is almost identical to what I am asking. That post is here: http://www.vcfed.org/forum/showthread.php?37362

I also found a cc-talk post that listed the pinout for the IBM 9331 disk drive (both in 8" and 5.25" sizes).

From the Service Guide (SA26-7094-00, First Edition, 1994) Drive and Signal
Cables page 7-5 (spelling errors left intact):
-----------------------------------------------------------------------------------------
External Signal Cable Connector

Table 7-1. Pin Assignments for 37 Pin D Shell Cable
Signal Name 		Signal Pin Ground Pin
Reduced Write Current 		2 	20
Drive Select 0 			8 	26
Motor On (Head Load) 		10 	29
Direction Select 		11 	29
Step 				12 	30
Write Data 			13 	31
Write Gate 			14 	32
Side one Select 		18 	36
Ready 				9 	27
Index 				6 	24
Track 00 			25 	33
Write Project 			26 	34
Read Data 			27 	35
Diskette Change 		19 	37
Two Sided 			7 	25
8-Inch Drive Attached 		5 	23
5.25-Inch Drive Attached 

Table 7-2. Attachment State Definition
5.25" Attached 8" Attached State Definition
	0 	0 		External Diskette Box NOT connected.
	0 	1 		8-Inch Drive Attached AND powered on.
	1 	0 		5.25-Inch Drive Attached AND powered on.
	1 	1 		Ext. Dskt. Box connected AND powered off.

Opening up the IBM 9331-011 (8") drive, you can remove the cable to the drive and just add a 50 pin cable and bypass the 37 pin external connector. If I get this set up, I'd like to see if I can add the FDADAP board internally in the 9331 case and rewire or use a different 37 pin connector. The 9331 drive is big and heavy ( to be expected) but is also bigger than the vintage case and 8" drive I already have made by Flagstaff Engineering.

Looks like the old post might help. Just following up in case anyone finds this post in the future. When I make the cable and play with the drive a little more, I'll post back.

Thanks,
Santo

 

[bear]

Thanks, I've been interested in this information for a little while and didn't realize it was already published. I thought I'd have to trace the connector(s) out myself!