two-dimensional approach of Computer Space with Space Invaders addictive gameplay of "completion" and "eliminate all threats". The unfinished game featured a giant, indestructible asteroid, so Rains asked Logg: "Well, why don’t we have a game where you shoot the rocks and blow them up?" In response, Logg described a similar concept where the player selectively shoots at rocks that break into smaller pieces. Both agreed on the concept. Hardware Asteroids was implemented on hardware developed by Delman and is a vector game, in which the graphics are composed of lines drawn on a vector monitor. Rains initially wanted the game done in raster graphics, but Logg, experienced in vector graphics, suggested an XY monitor because the high image quality would permit precise aiming. The hardware is chiefly a MOS 6502 executing the game program, and QuadraScan, a high-resolution vector graphics processor developed by Atari and referred to as an "XY display system" and the "Digital Vector Generator (DVG)". The original design concepts for QuadraScan came out of Cyan Engineering, Atari's off-campus research lab in Grass Valley, California, in 1978. Cyan gave it to Delman, who finished the design and first used it for Lunar Lander. Logg received Delman's modified board with five buttons, 13 sound effects, and additional RAM, and he used it to develop Asteroids. The size of the board was 4 by 4 inches, and it was "linked up" to a monitor. Implementation Logg modeled the player's ship, the five-button control scheme, and the game physics after Spacewar!, which he had played as a student at the University of California, Berkeley, but made several changes to improve playability. The ship was programmed into the hardware and rendered by the monitor, and it was configured to move with thrust and inertia. The hyperspace button was not placed near Logg's right thumb, which he was dissatisfied with, as he had a problem "tak[ing] his hand off the thrust button". Drawings of asteroids in various shapes were incorporated into the game. Logg copied the idea of a high score table with initials from Exidy's Star Fire. The two saucers were formulated to be different from each other. A steadily decreasing timer shortens intervals between saucer attacks to keep the player from not shooting asteroids and saucers. A "heartbeat" soundtrack quickens as the game progresses. The game does not have a sound chip. Delman created a hardware circuit for 13 sound effects