[Coco] Educate me about Y-Cables

[RETRO Innovations]

On 2/22/2015 11:20 AM, Francis Swygert wrote:
> 1. Run a survey -- how many ports are really needed? Four or five should do it. Floppy controller, HD controller, RS-232 pak, and one more. Most who use an SD pack don't use a physical HD. So that would leave a single open slot to play with if just four.  I think five would be more than sufficient for most, and would keep cost down a few bucks.
More slots is fine, but more "switched' slots is a big deal.  The big 
question is how many switched slots are needed.
>
>
> 2. What's the deal with using IDE cable? It's 80 pin flat cable rolled up in a sheath. The CoCo slot has 40 pins. With 80 position cable every other line should be a ground for shielding. So what's up with the "only xx data lines"? Doesn't matter what IDE has, you're just using cable.
That's what I thought as well, but it is not done that way.  The 40 
additional lines are attached to 7 already present ground lines on an 
IDE cable (the connectors do this, not the cable).  So, that's 33 IO 
lines, and 7 ground lines (=40).  Additionally, IDE does not expose the 
pin on pin 20  (there's a key there), so that's 32, and then pin 34 is 
hacked off on the controller side of the cable (=31) (to deal with 
master/slave decoding) You can read all about it here:

http://www.allpinouts.org/index.php/Ultra_ATA_66/100_IDE

Jim

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