Changes

These replicate the cables used to connect the system to the TV. They vary in quality, with the lowest being RF, then composite, then s-video and RGB (scart) being the highest quality. Many systems emulators have NTSC filters built into them. They can also be separately downloaded in .filter format. They were developed by [http://slack.net/~ant/libs/ntsc.html blargg]. Possibly others? More history.