[Coco] 3.5" floppy cable

[Bruce W. Calkins]

It is indeed the drive select lines that need the twist.  The original CoCo 
drives had the drive select lines jumpered together and the teeth were 
pulled from the connectors.  Any drive with proper drive select 
jumpers/switches with a normal full toothed connector works OK with the CoCo 
controllers.
Bruce W.
===================

----- Original Message ----- 
From: "Kip Koon"

> Hi Darren!
> I've looked at the floppy connector pin out for floppy drives quite a bit.
> I don't understand why swapping the "Motor Enable Drive 0" signal on pin 
> 10
> with the "Drive Select 1" signal on pin 12 will cause a floppy drive that
> functions normally as drive 1 function as Drive 0.  Are the floppy
> controllers for the color computer doing some non-standard (also read as
> crazy) things with the floppy drives or is there another floppy pin out 
> I'm
> not aware of?  Another strange thing that happens is the standard PC 
> floppy
> cable twist of wires 10 - 16 causes a drive that functions as drive 0 or 1
> to function as drive 2 or 3 respectfully on a standard DECB 1.1 unmodified
> rom in tests I've performed.  I definitely was not expecting this result.
> All this is quite puzzling to me.  The standard floppy connector pin out
> does not lead me to believe this would ever be the case, so what are the
> floppy controllers for the Cocos doing?  One more thing, why aren't the
> drive selects and motor enabled signals for drives 2 & 3 shown in the 
> floppy
> drive pin outs I have looked at.  I remember in the good 'ole days of 
> 8-bit
> computing that I could jumper a drive for drive 0, 1, 2, or 3.  I have 
> some
> 5.25" floppy drives with jumpers to do just that in some cases.  Now that
> I'm thinking about all this, did IBM mess with the original floppy drive
> signal definitions?  It seems to me there was a defined floppy drive
> connector pin out standard that did include drive selects for all four
> drives numbered 0, 1, 2 &3.  If so, then there are definitely two 
> different
> floppy drive connector pin outs!  Thank you in advance for helping me to
> understand all this.
> Kip
>
> -----Original Message-----
> From: coco-bounces at maltedmedia.com [mailto:coco-bounces at maltedmedia.com] 
> On
> Behalf Of Darren A
> Sent: Saturday, November 09, 2013 5:41 PM
> To: CoCoList for Color Computer Enthusiasts
> Subject: Re: [Coco] 3.5" floppy cable
>
> On Sat, Nov 9, 2013 at 1:08 PM, Bill wrote:
>
>> I built a 3.5" drive cable, and after I put the 9-16 twist in it, the
>> drives light up when I type in DIR2 or DIR3. Is the twist for a coco
>> 3.5" floppy different than for the PC?
>>
>>
> If you are using two drives with a CoCo, and both are configured to be 
> Drive
> 1 (standard PC setting) then you need a cable with a twist of wires
> 10-12 only.  The drive attached after the twist will be recognized as 
> Drive
> 0.
>
> Darren
>
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