[Coco] PC-to-CoCo floppy drive cable

[Bill Barnes]

Here's what I got on a Floppy Drive cable, without all the garbage of the IBM twisting getting in the way (IBM uses a twist on 10-16):

Not ALL signals show up for the CoCo.

All ODD numbered lines are ground: 1-33

02 reduced write/Density (DD/HD? or SD/DD, unsure) (Shugart: Disk Change)
04 NC (Shugart: DS3)
06 NC (Shugart: In Use)
08 Index

The Next 4 pins are the ones that IBM messses with
10 DS0 (Shugart: DS 0) (IBM: 
12 DS1 (Shugart: DS B)
14 DS2 (Shugart: DS 2)
16 Motor on

18 [step] Direction Select
20 step
22 Write Data
24 Write Enable
26 Track 00
28 Write Protect
30 Read Data
32 Side [1] Select (CoCo: DS3)
34 Disk Change (Amiga: Drive Ready)

NOTE: Shugart Interface Definitions are different on pins 2,4,6, and 34.
NOTE: The Shugart Definitions predate the IBM hack.
NOTE: The CoCo does not use pins 2,4,6, or 34.
NOTE: The CoCo, when using single sided drives, uses Side select as DS3.

Sounds like an IBM floppy cable will work though for this.

Sources:
http://pinouts.ru/Storage/InternalDisk_pinout.shtml

floppy disk controller schematics.

-Later!   -WB-    -- BABIC Computer Consulting.


--- On Wed, 11/12/08, Roger Taylor <operator at coco3.com> wrote:

> From: Roger Taylor <operator at coco3.com>
> Subject: [Coco] PC-to-CoCo floppy drive cable
> To: "cocolist for Color Computer Enthusiasts" <coco at maltedmedia.com>
> Date: Wednesday, November 12, 2008, 12:11 PM

> I'm having trouble locating the pinouts for the CoCo
> floppy cable.  Is this hard to believe?  I've looked in
> almost every CoCo manual I have and many technical PDF docs
> with no luck.  After hundreds of posts on the subject over
> the years and lots of CoCo tech documents on the web,
> nothing is turning up after 1 hour of digging.
> 
> Anyway, I'm trying (yet again) to wire a PC 3.5"
> drive (hard-wired as Drive 1) to be seen as Drive 0 on the
> CoCo.  The drive currently is seen as Drive 1 and works
> good.  I'm using a cable I apparently hacked in the past
> but later I lined the ribbon wires back up normally and
> crimped it back to work with normal CoCo floppy drives.  I
> know I need to swap or twist a few of the ribbon wires, but
> I have no clue which ones they are now.
> 
> It seems like this should be written in stone and easy to
> find, and I've found this info in the past which is why
> I'm wondering where it is hiding on the web.
> 
> Any help?
> Thanks
> -- Roger Taylor