Below is some common technical info regarding the Color Computer line. There are many areas of similarity across all Color Computers, such as the serial and cassette ports. There are also differences:

CoCo 2 keyboard is identical, except no CTRL, ALT, F1, or F2

CoCo3 Joystick port - CoCo 1 & 2 only have 5 pins

All of the documents were useful, to me, when I started back working with the CoCo again. I hope you find them as useful as I did.