Atari 2600RGB (Tim Worthington)

This is a board for the Atari 2600 which adds audio/video outputs to this console which has only a modulated RF output available normally. It improves the picture quality and makes it easier to connect to modern TV sets that no longer have an analog tuner.

It works in a similar manner to Tim's NESRGB board. That is, it sits between the CPU and TIA (the name of the Atari graphics chip) and stores the data which meant to be written to the TIA palette registers. The TIA is fed with dummy colours instead. The various luma outputs from the TIA, in addition to the colour data stored is then used to create a RGB version of the original video signal. Essentially, the board creates the RGB video signal by bypassing the colour generation logic in the TIA. The video timing is unchanged.

With an extra button installed into the joystick, the user can control the Select and Reset switches, as well as change the palette and pause the console. These extra features are optional, but recommended as it removes the need to sit next to the console (within reach of the reset switch) when playing.

The board may be installed into all models of Atari 2600. The 2600jr model installation is much more difficult than the others because the reduced height of the console makes it impossible to install directly over the TIA spot on the motherboard.

Features:

• RGB, S-Video, and Composite Video outputs
• Audio output
• Six different colour palettes (three NTSC, three PAL) to choose from. The palette may be selected with and extra button installed on either the console or on the controller.
• Switches between PAL and NTSC palettes automatically by detecting 50/60 Hz output.
• Palettes may be modified by the user (requires a serial EEPROM programmer).
• Supplied with a switching power supply board, audio/video connectors, push-button switch, and other assorted bits that may be required for installation.
• If the extra button is installed on the controller, it can be used to activate Select and Reset remotely, as well as change the palette.
• Easy installation if the TIA is already in a socket.

How to use

The extra button mounted on the joystick can activate three functions.

• Extra + Up = Select
• Extra + Down = Reset
• Extra + Fire = Palette switch.

The palette switch may also be a second button mounted on the Atari. The palette switch performs different functions depending on how long you hold the button down.

• < 0.4s = Pause toggle. A quick tap of the button will pause/unpause the console. Because this is a hardware pause of the CPU, the video signal will cut out while the console is paused.
• < 2.5s = Select next palette.
• < 10s = Select palette #1.
• < 20s = Automatic PAL/NTSC game detect toggle. Enabled by default. This will allow only the selection of PAL palettes for PAL games and NTSC palettes for NTSC games. It uses the refresh rate to determine the game type. This should be disabled to play PAL60 homebrew games with correct colours.
• < 30s = Pause toggle. Disabled by default. The pause feature may be annoying for some people so it is disabled by default. Hold the palette switch while powering on the console to enable/disable the 2600RGB board. When disabled, the original RF output will work as usual but there will be no video output from the 2600RGB board.