games can be ported to the NES with modifications to the console including extra memory banks and additional DIP switches. Version differences Some games differ from their Famicom or NES versions. For example, VS. Super Mario Bros. is considerably more difficult than Super Mario Bros.; some of the levels were reused in Super Mario Bros. 2 for the Family Computer Disk System. Some games' graphics differ; for example, VS. Duck Hunt has more details and animation sequences. History In 1980, Data East had introduced the concept of a convertible arcade system board, or arcade conversion system, with the DECO Cassette System, but it was not a major success. The first successful arcade conversion system is Sega's Convert-a-Game system in the early 1980s. Its success led to several other arcade manufacturers introducing their own arcade conversion systems by the mid-1980s, including the Nintendo VS. System in 1984. The Nintendo VS. System is important in the history of the Nintendo Entertainment System. The Vs. System is the first version of the Famicom hardware to debut in North America during 1984, the success of which proved the market for the official release of the NES console. Following the video game crash of 1983, the North American home video game market had collapsed. Nintendo's negotiations with Atari to introduce the Famicom in North America failed due to Atari's collapse, and Nintendo of America's market research garnered warnings from retailers and distributors to stay away from home consoles, with US retailers refusing to stock game consoles. Meanwhile, the arcade game industry also had a slump as the golden age of arcade video games ended, but the arcade industry recovered and stabilized with the help of software conversion kit systems, such as Sega's Convert-a-Game system, the Atari System 1, and the Nintendo-Pak system. Hiroshi Yamauchi realized there was still a market for video games in North America, where players were gradually returning to arcades in significant numbers. Yamauchi still had faith there was a market for the Famicom, so he introduced it to North America through the arcade industry. Nintendo based the VS. System hardware on the Famicom, and introduced it as the successor to its Nintendo-Pak arcade system, which had been used for games such as Mario Bros. and Donkey Kong 3. Though technologically weaker than Nintendo's Punch-Out arcade hardware, the VS. System was relatively inexpensive, fulfilling Gunpei Yokoi's philosophy of "lateral thinking with withered