XG-1

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The Atari XG-1 Light Gun

The XG-1 is the light gun that came bundled with the Atari XEGS. Released in 1987, the XEGS, which stands for "XE Game System", was an Atari 65XE computer reworked cosmetically to give the appearance of a game console. The light gun was bundled to compete with the Nintendo Entertainment System. The XEGS came with one light gun game, called Bug Hunt. The XG-1 is compatible with the Atari 7800 video game console. And since the Atari 7800 is backwards compatible, the XG-1 also works on the Atari 2600. Atari eventually released four games on the 7800 that used the gun: Alien Brigade, Barnyard Blaster, Crossbow, and Meltdown.

The XG-1 is simply a specialized light pen. Light pen support was built into the earliest Atari computers, but it never really caught on. In fact, all lightgun games for the XEGS could be played with the light pen and vice versa. Many users complained of horrible accuracy of the device, especially when compared to the NES Zapper. Some XEGS users preferred to rewire the Sega Master System Light Phaser for use.

[edit] Accuracy

The Atari 400/800 Hardware Technical Reference recommends a "calibration procedure" each time the light pen is used, so that the software can compensate for this offset. A calibration procedure would improve the accuracy of the light gun. But both Bug Hunt and Barnyard Blaster for the XEGS both have "hard-coded" values, different ones in fact. While Bug Hunt appears to shoot slightly to the left, Barnyard Blaster seems to shoot slightly to the right. The Y readings for the gun are more predictable, equal to half the number of the currently displayed scan line.

The gun won't return reliable readings at all if the intensity of the display is too low. That's why the screens for Atari light gun games may be brighter than usual. The game screen will momentarily flash white whenever the trigger is pressed in either Bug Hunt or Barnyard Blaster. While the screen is all white, the software reads the gun position and provides the most accurate values.