[Coco] An FPGA GIME project, and CoCo FPGA Experimenter's Board

[Zippster]

I think I will do the Experimenter’s board first.  It shouldn’t take too long,
will give me some practice with the BGA packages, and may prove to be a
useful tool in developing the GIME project.

I think I have the interface to the CoCo port (level shifters) all figured out.
A couple of things I want to put on the board for sure will be a VGA port, and sound
out (resistor DACs).  So it could be configured as a video card similar to a
WordPak, or a sound board (among a multitude of other things).

It looks like the interface to the cart port will use up 42 FPGA pins, so there
will be 130+ for other stuff!  I think you could probably make the ultimate I/O board
out of this thing.  :)

- Ed

> On Oct 21, 2015, at 9:59 PM, Brendan Donahe <brendan at polylith.com> wrote:
> 
> They both sound interesting, but the latter sounds especially cool.
> 
> Brendan
> 
> On Wed, Oct 21, 2015 at 9:44 PM, Zippster <zippster278 at gmail.com> wrote:
> 
>> Good point Bill, I’m definitely considering complete CoCo3 compatibility
>> to be a must.
>> 
>> A CoCo3 mode would be baseline operation for sure.  We will stick to
>> normal GIME behavior and stock CPU speeds for that.
>> 
>> - Ed
>> 
>> 
>>> On Oct 21, 2015, at 9:22 PM, Bill Nobel <b_nobel at hotmail.com> wrote:
>>> 
>>> You know what Ed, GO FOR IT…  You would be the one to do this.  One
>> suggestion, make a mode switch like the 6309 to enable the enhanced
>> features beyond the Coco3.
>>> 
>>> Bill Nobel
>>> 
>>>> On Oct 21, 2015, at 7:28 PM, Zippster <zippster278 at gmail.com> wrote:
>>>> 
>>>> Hi guys, these are a couple of cross posts from the Facebook group for
>> people on the mailing list that don’t use Facebook.
>>>> I’m planning another project to follow the MC6847 FPG VGA boards, and
>> there’s been a little discussion over there.
>>>> 
>>>> 
>>>> FPGA GIME PROJECT
>>>> 
>>>> I've started doing some of the prep work for an FPGA GIME chip
>> replacement project. This is a stepping stone toward a CoCo4 project.
>>>> 
>>>> What I'm planning on is to develop a drop in board for the CoCo3 that
>> will implement a GIME in FPGA, with 2MB of static RAM, and direct VGA out.
>>>> 
>>>> I'll be using an Altera Cyclone IV FPGA for the project. Since more I/O
>> pins will be needed than are available on Cyclone IV QFP packages, this is
>> going to require me to use a BGA256 packaged FPGA and a four layer PCB.
>> Toward this end I have a reflow oven on the way, and I'm entering the
>> needed parts into Eagle. This will give us quite a few pins to work with in
>> implementing new features later.
>>>> 
>>>> This is going to be a very interesting and challenging project in
>> several ways, but it's the big missing part of the puzzle hardware-wise to
>> a fully CoCo3 compatible CoCo4, so hopefully it will be worth the effort.
>> :)
>>>> 
>>>> 
>>>> COCO FPGA EXPERIMENTER’S BOARD
>>>> 
>>>> As I've been entering parts preparing for the FPGA GIME project, I had
>> an idea. With the work I'm having to do for that project, it would be
>> relatively easy to develop an "FPGA Experimenter's Board" that would plug
>> into the CoCo cartridge port along the way.
>>>> 
>>>> Kind of an FPGA development board that could be used for interfacing
>> projects. With an Altera device, some bi-directional level shifters, maybe
>> an ADC chip, a couple of resistor DACs, and some other support circuitry,
>> we could have a pretty cool board for people interested in CoCo/FPGA
>> projects. Maybe help get some more hardware developed.  :)
>>>> 
>>>> Is there enough interest in something like this for me to pursue it on
>> the way to doing the GIME replacement?
>>>> 
>>>> What do you guys think?
>>>> 
>>>> 
>>>> - Ed
>>>> 
>>>> 
>>>>