NES.app uses the popular InfoNES emulation core to mimic the 6502 processor in a Nintendo Entertainment System, allowing you to play ROM dumps of games designed for the NES console. ROM dumps are files containing the dumped instruction code from a physical cartridge.

Changes since v0.50:

[nervegas] added “Enlarge Screen” option for portrait mode
[nervegas] aesthetic changes to preferences

http://iphone.natetrue.com/nesapp/