[Coco] Building dual drives

[Kip Koon]

Hi Bill,
I have a Dual 5.25" 40trk DSDD vertical drive setup that was not working, though it seemed like it should have.  Then I noticed that the termination resistor pack (a single inline pak) was not present, so I put a 3.5" floppy drive at the end of the cable to provide termination for the signals in the cable and it works great!  I obviously had to build my cable from scratch since this one had a round cable on it made for just two drives.  
I need to mention one vital point on putting connectors for 3.5" drives on ribbon cables.  Some 3.5" floppy drives have the notch in the plastic shroud on the side opposite the side from pin 1.  If you put the 3.5" 40-pin IDC connector on your ribbon cable correctly and plug into the "backwards" connector on the 3.5" floppy drive, none of the signals will line up.  This may be the situation in your case.  No matter what you do, if the notch in the plastic housing of the connector is on the opposite side from pin 1 and you don't notice this, then the drive will never be accessed correctly.  The drive will just do crazy things.  
Depending on how I jumper my drives, I have a 5.25" drive 0 & 1 and a 3.5" drive 2 or a 5.25" drive 0 and 2 and a 3.5" drive 1.  If you use the back side of 0 as 2 and 1 as 3 like HDB-DOS does, then under RS-DOS the 3rd drive is never accessible.  Of course I have to remove the case to make the jumper changes.  I hope this helps Bill.  Let me know if you have further questions.

Kip Koon
computerdoc at sc.rr.com
http://www.cocopedia.com/wiki/index.php/Kip_Koon



-----Original Message-----
From: Coco [mailto:coco-bounces at maltedmedia.com] On Behalf Of Bill
Sent: Friday, February 27, 2015 3:14 PM
To: Coco Enthusiasts
Subject: [Coco] Building dual drives

I’ve been trying for a week or so to build a dual drive system with (1) 5 ¼” and (1) 3 ½” drive in the same box. No matter how I build the cable it don’t work. Does anyone have a drive setup like that? How is the cable designed?

Thanks

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