[Coco] Model III bus pinout

[Ward Griffiths]

On 03/05/2006 04:28 am, Willard Goosey wrote:
> I spent a good hour digging through a Model 4 tech ref for this:
>
> xa0 - 17
> xa1 - 19
> xa2 - 21
> xa3 - 23
> xa4 - 25
> xa5 - 27
> xa6 - 29
> xa7 - 31
> xd0 - 1
> xd1 - 3
> xd2 - 5
> xd3 - 7
> xd4 - 9
> xd5 - 11
> xd6 - 13
> xd7 - 15
> extiosel* - 43
> xin* - 33
> xout* - 35
> xreset* - 37
> xmi* - 47(?)
> xorq* - 49
> xiobuswait* - 41
> xiobusint* - 39
> nc - 45
> gnd - 8-50 even
>
> As you can see, it's an expansion bus, it's not SASI or SCSI, dispite
> the fact that it's a 50-pin ribbon cable connector.
>
> Sheesh!  Next you'll wanna hook 8" floppy drives to your SCSI cards,
> just 'coz they use the same connector.

Mod 4 tech ref was a bit clumsy, as it assumed that a Mod 3 tech ref was ready 
to hand (as happened with the Mod 16 and 6k assuming Mod 2 or 12 info).

I can't seem to find the message I'd set aside to answer, that said the Coco 
adapter provided the same bus as the 2/3/4/12/16/6000.  The bus was 
specifically the 3/4.  2/12/16/6k used a quite different bus.  The bus 
adapter (that took up a valuable slot in a small card cage) for the 
2/12/16/6000 cost much more than the Coco adapter (and we sold a lot more of 
them) since it was for "business" machines.

For anybody who cares, the HD bus adapter for the Mod One was more expensive 
than that for the Coco and involved even less circuitry.  No, I don't 
currently own either.  (As Franklin once said, "three removes == one fire).

My HD interface for my Cocos and my Mod One and 4 is a serial cable to a Linux 
box.  Same cable I use to back up my 6k via uucp.  (I'd estimate that less 
than 2% of Linux users even know that uucp exists, and less than 2% of those 
left know how to use it).

I really have to look at Boisy's DriveWire.  Since it'd make some actions 
easier, and I won't deny that I'm a lazy bastard.  Extending the interface to 
Mod 1/3/4 and Mod 100 is something I'd like to work on.
-- 
Ward Griffiths    wdg3rd at comcast.net

I think boys might benefit from owning a Barbie doll; every young man
should understand what an expensive proposition it is to cohabitate with
a narcissistic woman built like a stripper.  --  Tony Woodlief