CoCo3FPGA analog board

Gary Becker’s CoCo 3 FPGA project implements a Color Computer 3 running on
an Altera DE1 Cyclone II FPGA development board.

The CPU core runs at 25MHz. Communication using just the DE1 is via serial,
using Drivewire for storage currently. Hopefully the on board SD card slot will
be used in the future.

Gary has designed an add on board that connects to the GPIO ports on the DE1,
adding 4 megabytes of RAM, two joystick ports, a WiFi module, and RTC module.
It’s known as the CoCo 3 FPGA analog board.

Original CoCo 3 FPGA analog board on DE1

I was asked to help in the manufacture of some of these, so I did a re-layout of the board, also trying to refine it a bit more in how it would go together with the dev board. Here are some test boards I received back. The silkscreen graphic will be slightly different on the final boards. Originally, the analog board was to be on top, outside the plexiglass cover of the DE1. This made for some really long connectors to the GPIO sockets.

I decided we should go for mounting the analog board underneath the top cover, using appropriate standoffs, etc. In fact we will be getting new acrylic top plates made that will not have the cutouts that the DE1 plate has, just to make a neater package.

Here are a few pics of the test boards, that make it a bit more clear what I’m going for in fitting Gary’s board to the DE1. The parts are just set in place.

As I mentioned, we hope to have new top plates that will be the same size as the DE1 footprint, and no cutouts. It should look pretty good. I have a few things to reposition slightly on the board before the main run, including the WiFi module.

The silkscreen on the final boards will look like this…