Atari 2600:Video Output Notes
All Atari 2600 consoles, regardless of region or variation, output audio and video through RF. Considering the console was designed in the mid-1970s when composite video on consumer TVs was practically unheard of, this is not too surprising. However, all 2600 consoles can be modified for almost any analog video output, from composite video to RGB. Simple mods exist which amplify the internal composite video signal going to the RF modulator, as do more advanced mods which output S-video and encoded composite video using the raw chroma and digital luma signals coming from the TIA chip. The 2600RGB board from Tim Worthington takes this a step further by grabbing the raw palette data sent to the TIA to help generate an RGB video signal, which is also encoded to S-video and composite.
French Consoles
French Atari 2600 units were made to support the SECAM video standard. Essentially, the colors took the eight shades of gray from the black and white output mode, then assigned a color to each shade. The resulting image is often very different from the original intended image, as shown below.