Some possible ratings reach from "Rookie" to "Star Commander". Wanting to make an action-oriented "Star Trek"-type game, Doug Neubauer designed "Star Raiders" in about eight to ten months while working for Atari. He left the company while the game was still a prototype to return home to Oregon and join Hewlett-Packard, and reported that it took him six months to reach the highest player-level during development. "Star Raiders" was unusual at the time for Atari, as it made relatively few game cartridges for its computers, with most being adaptations of Atari 2600 titles. The main simulation continues running even when the user is interacting with other displays. For instance, one might be attacked while examining the Galactic Map. This was unusual for the time, if not unique. The primary playfield/star field is drawn in the graphics mode that provides 160×96 bitmapped pixels utilizing four color registers at a time out of a palette of 128 colors provided by the CTIA chip in the early Atari computers. This is called ANTIC mode D, but accessed in Atari BASIC by use of the "GRAPHICS 7" command. The Atari's use of an indirect palette means that color changes associated with the presence or absence of energy shields, emergency alarms, and the screen flash representing destruction of the ship can be accomplished by simply changing the palette values in memory registers. Enemy ships, shots, and most other moving objects use Atari's variant of hardware sprites, known as "player-missile graphics", which have their own color registers independent of the current screen graphics mode. The radar display in the lower right of screen is drawn using the background graphics, and updated less frequently than the sprites. The debris particles emitted when an enemy ship is destroyed are calculated as 3D points. Since the 6502 processor in the Atari 8-bit family does not have a native multiply or divide command, the game slows down considerably when several of these particles are active. The Atari 8-bit family allows different graphics modes and color palettes to be used in different horizontal bands on the screen, by using a simple display list and a type of horizontal blank interrupt. While other games make more extensive use of these techniques, "Star Raiders" uses them in a relatively simple fashion to combine text displays and graphics; the cockpit display uses a custom character set to display futuristic-looking characters and symbols reminiscent of MICR. "Star Raiders"' sounds of engines, shots, explosions, alarms, etc. are algorithmically synthesized directly using the POKEY sound chip's capabilities.