Checking video resolution.

Ok, relatively new to analogue video resolution (from a videophile perspective). What's the best method for checking the video output from games consoles. Ie 240p, 480i, 480p, 720p.

I'm trying to force 240p on the Panasonic 3DO which natively outputs 480i but not sure on how to check if it's worked.

 

If you are using a CRT, then trust me. You would notice if it worked. Suddenly there would be no interlace flickering, image would be stable. And the scanlines, even on a consumer set. Are noticeable.

 

I thought that might be the case. i have a HDTV which tells me the resolution of digital feeds through the hdmi but doesn't tell me anything through composhit. I have a CRT which has s-video so maybe I will have to check on that for improvement in picture.