[Coco] 3.5 drives was drive motors

[Lothan]

Actually, the drives are pin-for-pin identical. The difference is whether 
the drive has jumpers for drive select or has drive select soldered in place 
for a PC (in which case it may need some portion of the cable twisted to 
swap drive select). Way back in the day I had a couple of Teac 3.5-inch 
drives with drive select jumpers, but (as Gene indicates) these may be as 
rare as hen's tenth today.

-----Original Message----- 
From: Bill Pierce
Sent: Saturday, July 13, 2013 11:49 AM
To: coco at maltedmedia.com
Subject: Re: [Coco] 3.5 drives was drive motors


Robert,
I'm not sure but I think the two connectors are not pin for pin compatible. 
I seem to remember that you have to switch a couple if not several pins to 
make it work properly. One of my 3.5 drives (my current drive 0) came 
configured for the Coco with a case and an internal 5.25 to 3.5 adapter 
plate with an 34 pin adapter on the plate. A regular Coco drive cable is 
used, then internally it cables to a 34 pin connection like used on the 3.5 
drives. In the cable run, from the internal side of the card edge to the 34 
pin, there are several wires crossed to other pins. They are not direct pin 
for pin connected. I also have a cable that is set up for a 5.25 and a 3.5 
drive. In that cable, after leaving the 5.25 (drive 0), several wires are 
split from the ribbon and crossed to different pins for the 34 pin 3.5 
connector. I know I'l be corrected if I'm wrong.

Also, if you're using an 3.5 HD drive (1.44 meg). It must be jumpered to 
work as 720k or it will not work. If there's no jumpers, then it's the wrong 
type drive. It seems I remember that some drives would go into 720k mode if 
you cover the hole on the upper left of the disk, but I think that's only on 
a PC. The HD disks will work on a 720k drive but will possibly fail 
eventually. Something about the 720k write heads not being strong enough for 
the HD media. Anyway, it's best to have 720k disks (DD).