[Coco] CoCo Disk Drives

[Rick Thornquist]

Al -

Sounds great - thanks for the help!

- Rick

On Fri, Feb 27, 2015 at 2:00 PM, Al Hartman <alhartman6 at optonline.net>
wrote:

> Rick,
>
> Texas Peripherals was a cooperative venture between Tandy and Tandon to
> manufacture disk drives. These drives are cost reduced versions of the
> Tandon TM-100-1 floppy drive.
>
> The 8 pads connected by traces are your drive selects. If you notice, all
> four are connected and unbroken.
>
> R51 is your Termination Resistor.
>
> Termination has to be in the last drive on the cable (usually drive 0 is
> the last connector, but someone made up your cable differently), so in your
> case that would be drive 1. Take the one out of drive 0, and tape it
> somewhere secure inside the drive so you can use it again if need be.
>
> -[ Al ]-
>
> -----Original Message----- From: Rick Thornquist
>
> Al and Gene -
>
> All right, I opened the drives up.  Even though they have different catalog
> numbers, they appear to be pretty much identical on the inside (then again,
> the catalog number on the 26-1164 is on a sticker over the previous one -
> I'll have to see what's under there someday).  Even the drive mechanism -
> Texas Peripherals (10-5355-001) - is the same.  Texas Peripherals?  Hmm...
> Doesn't sound quite legit. :)
>
> Anyway, here's a picture of the logic board of the 26-3029:
>
> https://dl.dropboxusercontent.com/u/18477511/26-3029%20Logic%20Board.jpg
>
> There doesn't appear to be any DIP switches or jumpers for drive select,
> instead there appear to be four drive select lines in the bottom right or
> the logic board - DS 1 2 3 4.  I guess they expect you to do the drive
> selection with a pulled pin cable.  Fine with me.
>
> As far as the termination pack is concerned, I'm thinking that it's R51,
> right above the drive select lines.  It has six pins.  Please correct me if
> I'm wrong!  Both drives have this pack so it seems like I have to remove
> one of them.
>
> Here's the thing.  The pulled pin cable is set for drive 0 in the middle of
> the cable and drive 1 at the end.  You all are saying that the termination
> pack should only in the drive at the end of the cable, so that will be
> drive 1.   That also sound good, but Service Manual that I found says on
> page 5 (page 8 of the PDF), "The Resistor TerminatIon in the IC socket is
> used in Drive number zero only. It must be removed for Drives one. two and
> three."  But my drive 0 is in the middle of the cable!
>
> Here's the Service Manual:
>
> https://dl.dropboxusercontent.com/u/18477511/Radio%20Shack%
> 20Mini%20Disk%20Service%20Manual.pdf
>
> So, where should the terminator be, on drive 0 (like the manual says) or
> drive 1 (at the end of the cable)?
>
> - Rick
>
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