Then moved up to the Radio Shack Color Computer II. Then a member of the Sacramento Color Computer Club in the mid 1980's, the president notified us that one of the local RS stores had the Coco-II's basic model with 16 KB memory on clearance for only $20 each. I bought 2, gave 1 away. Opened it up, following instructions from I think it was a home computer magazine article, upgraded it to 64 KB by unsoldering the 2 RAM chips, then custom wiring the 64 KB by adding a few soldered jumper wires and cutting a few traces. Replaced ROM with an EPROM burned by the club with extended Basic into a socket that I replaced the soldered in ROM with trace cuts and jumper wires.
Was working various local bulletin boards with Mickeyterm modem software and RS 300 Baud modem using the CoCo's native 32 character wide by 16 line screen.
Replaced the ROM with a socket for EPROM on the floppy disk expansion module card, cut a trace or two and added a jumper wires soldered in, purchased A-Dos, made custom changes I wanted saved to floppy (prior to EPROM mod). Club burned me a new EPROM, installed it for enhanced commands.
Bought a surplused 4 inch wide thermal printer from an electronics store in Sacramento, CA, made a custom serial cable to the RS 4 or 5 pin DIN connector. Used a PNP transistor and two resistors as a primitive digital inverter to flip the READY line so it would work with the RS. I paid under $100 for it. This was when printers were going for upwards of $500 used to thousands new.
Also added some circuitry and a toggle switch using a quad XOR chip to the CoCo's Motorola 6847 video controller chip, to enable enhanced color modes and invert color not otherwise available as it was hard wired.
Also played around with the Tano Dragon II, a Taiwanese RS clone that I bought on reduced clearance price from a computer electronics surplus outfit west of Long Beach, CA (Torrence?) that now escapes my mind as to name. I think I paid $100 for it.