Nintendo VS. System

The Nintendo VS. System (任天堂VS.システム, Nintendō Bāsasu Shisutemu^?), officially sold simply as the VS. System (VS.システム, Bāsasu Shisutemu^?), is a coin-operated video game platform designed for two-player competitive play using the VS. UniSystem or VS. DualSystem, arcade system boards based on the Nintendo Entertainment System. Many of these stand-up or sit-down arcade machines had two screens and controls joined at an angle. These games were ported to arcade hardware from existing home video games for the Family Computer and Nintendo Entertainment System; thus, they could be sold cheaply to arcades in the late 1980s.

The VS. System was designed primarily as a kit to retrofit Donkey Kong, Donkey Kong Jr., Popeye, and Mario Bros. machines; as such, they require the same special monitor that these coin-ops use. These monitors use inverse voltage levels for their video signals as compared to most arcade monitors. Commercially available converters allow one to use any standard open frame monitor with the game.

Almost all the games on the VS. System run on identical hardware. Notable exceptions are that four special PPUs, or video chips, were also made; each chip contains a different palette, each of which appears to arrange the colors completely randomly. Most boards can be switched to a new game simply by swapping the program ROMs, though the appropriate PPU must also be used; if not, the game will appear with incorrect colors. Several of the later VS. games employ further measures of protection by using special PPUs which swap pairs of I/O registers and/or return special data from normally unimplemented regions of memory. Attempts to run these games in other VS. Systems will result in the game failing to even start.

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