The is an arcade system developed and produced by Nintendo from 1984 to 1990. It is based on most of the same hardware as the Family Computer (Famicom), later released as the Nintendo Entertainment System (NES). Most of its games are conversions from the Famicom and NES, some heavily altered for the arcade format, and some debuted on the VS. System before being released on the Famicom or NES. The system focuses on two-player cooperative play. It was released in three different configurations: upright VS. UniSystem cabinets, upright VS. DualSystem cabinets, and sit-down VS. DualSystem cabinets. Games are on pluggable circuit boards, allowing for each side to have a different game. The VS. System was a commercial success in the United States, with about 100,000 arcade cabinets sold, as the highest-grossing arcade machine of 1985. It was the first version of the Famicom hardware to debut in North America, in 1984. The system's success in the arcades proved the market for the official release of the NES console in North America in 1985. Hardware The VS. System was designed primarily as a kit to retrofit Donkey Kong, Donkey Kong Jr., Donkey Kong 3, Popeye, and Mario Bros. cabinets, so they require the same special monitor. These monitors use inverse voltage levels for their video signals as compared to most arcade monitors. Almost all VS. System cabinets have identical hardware powered by a Ricoh 2A03 central processing unit (CPU), the same in the Nintendo Entertainment System, except for special PPUs or video chips. Each chip contains a different palette that arrange the colors in different configurations chosen apparently at random. Most boards can be switched to a new game simply by swapping the program ROMs and the appropriate PPU or the game will have incorrect colors. Several of the later units employ further copy protection by using special PPUs which swap pairs of I/O registers or return special data from normally unimplemented regions of memory. Attempts to run these games in other VS. System models will result in the game failing to even start. Some dedicated double cabinets look like two games butted together at an angle, with a single motherboard. The Red Tent, a steel sit-down cabinet for the VS. DualSystem, allows play for up to four players simultaneously. It has the same motherboard as the double cabinet. Because the VS. System has the same CPU as the NES, its