The Tandy 128K Color Computer 3 model 26-3334. Click for larger view.
Pictured is a PRI Inc., CC Bus cart extender. The power supply that came with it is dead, and even with a replacement supply port 1 was the only working slot. I did not spend much time other than "re-seat the chips" and test the 7805 to be sure proper voltage was being transmitted. The power line on each slot was correct. Pictured in slot 1 is a 502 disk drive cart, and slot #3 has a CoCo MAX cart. Click for larger view.