The current configurations on my CoCo 3s are:
The first one:
The second one (currently being assembled):
The CoCo 3 is an extended version of the CoCo 2, the differences being improved text and graphics, a doubled clock rate, and the addition of a paged MMU to extend the memory addressing capabilities from 64k to 512k (actually 2M). All of the enhanced abilities are from the functioning of a custom chip called the GIMEI am currently working on an accelerator project for this machine, unfortunately taking advantage of the increased speed will require major revision to the OS.
Here are a few CoCo related sites.