Oddly, I never saw a TV switch box in the UK back in
the day - everyone I
knew with any kind of machine that used a TV for a display simply unplugged
the regular antenna and plugged the computer in when they wanted to use it.
I never saw one with a computer, they were more commonly used with TV games
consoles. I have one somewhere. Actually I think I've seen them in pound shops
(equivalent of dollar stores) recently, next time I am going around such places I
will have another look
I got a US one (300 ohm aerial I/O, 75 ohm computer input on an RCA phono
socket with internal balun) with my CoCo 3, which is the US NTSC version (it was
never sold in the UK, and trying to find the PAL version sold in Australia was
impossible). I have never used it, I use the CoCo 3 with an RGB monitor.
-tony