If you want to live the real life of 8-bit madness you need to track down an old tube TV. Connecting them to the Atari or C64 is amazingly easy.
RCA2RF
basically you only need a phono cable with a RCA (female) to RF (male) adapter, then screw that into the back of the TV
a phono cable can be one of those red+white cables, you'll only use one side, red or white it does not matter
that little box that that used to go between the computer and the TV is no longer necessary, new signals are digital> so the old TV can't pick up the signal> so there is no need for the computer vs antenna mode> it's all computer all of the time
the
harder to find is the RCA (male) to RF (female) adapter, if you do have one of these then any coax cable can be used from the computer>adapter>coax wire>TV
composite signal
something like the Commodore Amiga A520 outputs a composite signal, that cable will go to the TV's yellow input, in the old days this may be listed as VCR input, the TV's white input is for mono (combined) audio, if the TV has a white+red RCA (female) input then you've got a stereo TV - you're rocking now