[Coco] CoCo Disk Drives

[Gene Heskett]

On Friday 27 February 2015 09:21:00 Rick Thornquist wrote:
> Since you guys were so great answering my previous question, I have another
> for you.
>
> When I acquired my CoCo 3, I got a 26-3029 controller and two disk drives,
> a 26-3029 and a 26-1164.  I didn't get any manuals, so I just connected
> them up in what looked to be the right way.  I have the 26-3029 connected
> to the middle of the floppy cable (as drive 0), and the 26-1164 connected
> to the end of the cable (as drive 1).  The setup does work for the most
> part, but there is some flakiness, mainly with the 26-1164.
>
> My question: Is there some configuration, like with drive select dip
> switches or terminators, that I'm supposed to do?  Also, my Internet
> digging suggests that the 26-1164 is a TRS-80 disk drive - is it also
> supposed to work with the CoCo?  .
>
> Thanks!
>
> - Rick

Two things to pay attention to, Rick.

1. Only the drive connected at the end of the cable is supposed to have 
resistor packs installed to terminate the lines.  If both have them 
installed, thats too much of a load on the controller.  If none are installed
(empty 8 or 9 pin inline sockets) then you have to find a set and install them 
on the end drives pcb.

2. Generally speaking, MOST of these drives have a means of selecting which 
drive address they respond to, and because the default cable supplied by the 
shack actually does that with missing "teeth" in the edge connectors on the 
cable, and intend that the drive on the end of the cable is drive 0, I 
usually ditch those connectors and crimp on 34 pin card edge socket 
connectors that are fully populated so you can actually make use of the DS 
jumpers on the drives board, s/b 4 choices in 5.25" drives but only 2 on the 
3.5"ers. One and only 1 position is jumpered in this case.

However you jumper them, its the end of the cable drive only that needs the 
terminations installed.

No clue what the 26-1164 drive is, single head or double sided heads, but its 
likely that at that age, completely usable on the coco's, at least with 
os9/nitros9 when the descriptor is configured to match what the drive can do.

Cheers, Gene Heskett
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