# - official description1 - Service Manual

VCS means Video Computer System

Later Models were called Atari 2600

This console has no video frame buffer to feed the graphics to the display at the right time. So programmers had to use machine code to do it. This code for the display had to match the timing of the TV with no option to wait. Game logic need to happen in-between the display code. Running necessary game code in-between the display code was know as "racing the beam" since they were littering trying to make things happen before the electron beam in a TV advanced to the next pixel. An advantage to these difficulties it that programmers are free to use as many colors as they want, although this requires CPU cycles and leaves even less time to run game code. The Atari is technically limited to 56 colors per scan line, but 2 is a more practical limit. The pallet is limited to 128 colors. However, color limited are not insurmountable and 256 colors have been successfully displayed from a VCS.

One might notice the early Atari VCS consoles had a grill on top. Look really closely, one will notice the gaps in the grill where speakers should be. What's more, if one examines the circuit board, one would find places to soldier in the speaker wires.Pins #12 and #13 on the TIA chip are shorted together so that both channels are combined into a mono signal. Instructions are online how to simply get stereo audio out of these two pins. Since stereo was a planed feature, some games were designed for it, such as Combat. Later in the life of the VCS, and usually through 3rd party efforts, developers who knew about the internal stereo feature decided to design their games, such as Solaris, for stereo even though the likelihood of a home user ever hearing it was slim. Before released, the stereo speakers features were determined to make the console too expensive. Atari never reconsidered this decision for any of the later version of the consoles that continued manufacture into the 1990s.

Two portable clones of this console exist :
- Akor TV Boy released in 1991 in Hong-Kong (TV required)
- Dynacom MegaBoy released in 1991 in Brazil (built-in screen)
These two clones include 126 games but don't have any cartridge port.

Authorized clone from Sears (Sears Video Arcade):

Atari made an adapter to play 2600 games in the 5200. The adapter is actually a 2600 system (virtually all 2600 adapters are).

Other Clones:
Columbia Home Arcade
Coleco Gemini
Dynacom Dynavision
Goliath Game System
Intellivision System Changer (Intellivision adaptor)
CCE Supergame VG-2800
CCE Supergame VG-3000
Rambo
Bharat
RetroN 77
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