[Coco] 3.5 drives was drive motors

[Bill Pierce]

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).

Bill Pierce
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-----Original Message-----
From: Robert Hermanek <rhermanek at centurytel.net>
To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
Sent: Sat, Jul 13, 2013 10:45 am
Subject: Re: [Coco] drive motors


Ah, well here you touch on another topic that I've had trouble with:  I 
try on and off, but have never successfully connected any 3.5" device to 
my system.  The situation is...

Coco3, standard disk controller.  Using original ribbon cable that came 
with 5.25 drive, so all connections are card-edge style, and there are 
two connectors available for drives.  I picked up a second 5.25 drive at 
some point, hooked everything up, and have confirmed that with 2 5.25" 
drives, drive 0 and drive 1 respond normally, work perfectly.  So all 
controllers/cable are A-OK.

Next step:  I've been led to believe that pretty much any 3.5" drive 
will work... so I ordered a very clever little adapter that is female 
34-PIN IDC style connector one one side, and nice shiny gold card-edge 
male on the other.  So this give me a 5.25" style connector for any 3.5" 
drive.  I've been careful to double check PIN 1, making sure I don't get 
anything backwards.  I set all this up as drive 0.  At this point I can 
power up, and confirm that remaining 5.25" drive (drive 1) works 
perfectly still.

So:  controller to stock cable to card-edge adapter to 3.5" drive is the 
full connection for drive 0.  Drive 0 appears to respond normally, 
meaning drive select is correct, when I do a DIR0 the 3.5" drive lights 
up and heads move around.  I get an IO error of course, no formatted disks.

I've tried both new HD disks, as well as a factory sealed set of DD 
disks that I picked up, and have this result every time:  Try DSKINI and 
I get an IO error half way through.

Clarification on DSKINI:  What does it do exactly?  As anyone knows that 
listens to their drives, DSKINI sounds like it runs the heads down to 
one end, then slowly ticks through the tracks.  Then their appears to be 
a "stage two" where it again repositions the heads, and runs through the 
tracks more quickly.  Then the process is complete.  If we call this 
stages one and two, then I can say that my DSKINI operation always fails 
after stage 1 -- the heads position, all tracks are slowly advanced 
through, the heads position again, IO error.

Then I gave up for a  while.  More recently, I took a floppy emulator 
that I could not resist buying, and configured that in the exact same 
fashion as the 3.5" drive, and had the exact same result -- it appears 
DSKINI succeeds for some amount of time, then fails part way through.

I'll attempt a link to the emulator:

http://www.amazon.com/Updated-Version-SFR1M44-U100K-Floppy-Emulator/dp/B00C4PCK9S/ref=sr_1_1?ie=UTF8&qid=1373726291&sr=8-1&keywords=SFR1M44-U100K

I've tried both HD and DD media.  I've tried both 1.44 and 720k images 
on my emulator.  I've tried three different physical 3.5" drives -- one 
brand spanking new, the other two from the oldest PC systems I could 
find.  Always have the same experience.

...but I hear others simply hook up 3.5" drives and away they go. Thoughts?

Thanks,
-RobertH


On 7/12/2013 7:20 PM, Robert Gault wrote:
>
> Maybe it is the controller or the way you set jumpers and resistor 
> blocks in your drives. On my two floppy system, the only floppy that 
> turns on is the one in use.
>
> I have tested this with a Disto SC-II and two Tandy controllers using 
> the stock DOS1.1. One floppy is a 3.5" the other a 5.25" drive.
>
>


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