[Coco] [Color Computer] USB Anyone?

j_e_daggett j_e_daggett at yahoo.com
Sat Apr 16 12:28:36 EDT 2005

Beware that the MC2 bit of $FF90 Init0 register controls where the SCS
line is decoded from teh GIME chip. MC2 low then the SCS is decoded
from $FF50 to $FF5F. MC2 high will decode $FF40 to $FF4F.

Beisdes most PLD chips are $0.75 to $1.25. The IDE interface that is
functional equivalent to the Glennside IDE takes only 26 macrocells of
a 9572 series CPLD. IT won't fit into a 9536 do to the lack of pinouts. 

I still contend that one large CPLD device will beable to shrink the
board size significantly such that teh savings in board costs will
overide any extrra cost in the CPLD. It is a trade off. 

You can do what you wish.


--- In ColorComputer at yahoogroups.com, "James Diffendaffer"
<jdiffendaffer at y...> wrote:
> If I use addresses FF5C-FF5F I can use the bubble memory design
> exactly.  Using SCS simplifies address decoding so only A2, A3 and A4
> of the address buss need checked.  It *can* be done with one chip and
> it's output goes to CE on the USB chip.
> I only need 2 or 3 chips to add a 16 bit IDE interface to this and it
> sure wouldn't cost over $100.  At most another $10 in parts.
> 1 PAL/GAL + 2 74HCT373 chips would handle all the logic for USB, IDE
> and interfacing a ROM.
> My biggest roadblock is having to create a prototype board for the
> CoCo connector since that size is rare these days.  I have a board
> printing kit but cutting boards/edge connectors is a PITA.
> --- In ColorComputer at yahoogroups.com, "John R. Hogerhuis"
> <jhoger at p...> wrote:
> > On Sat, 2005-04-16 at 03:28 +0000, James Diffendaffer wrote:
> > > 
> > > Anyone interested in a USB interface?
> > 
> > 
> > FYI James Daggett made a run at this, and I think got as far as layout
> > so you might be able to collaborate with him from the hardware angle.
> > 
> > The starting point was http://microusb.org
> > 
> > If someone ever comes up with hardware, I'm willing to help with some
> > firmware. Plenty of driver work to go around since there are so many
> > possible devices.
> > 
> > -- John.

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