Are you sure it wasn't a Tandy 1000 EX:
Or 1000 HX?:
The CoCo didn't run "DOS". (Well, at least not MS-DOS.) It was a Motorola 6809-based 8-bit system that normally ran its built-in Microsoft BASIC-based environment. (There were several alternative OSes available for it, including the more-than-vaguely UNIX-ish OS-9 from Microware Systems.) The 1000EX/HX were sorta-mostly-PC compatible systems packaged in the odd home computer-shaped console case and had a few unique features, like a stripped down version of DOS in ROM they could boot from instead of a floppy.
I would love to find a broken EX/HX and cram a Mini-ITX-style motherboard into one.