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 v0.48:

[nervegas] Fixed minor memory leaks
[nervegas] Fixed remaining save/restore state issues (I think)
[nervegas] Moved all critical globals into a nes_state struct
[nervegas] Fixed a bug causing certain games’ save state to corrupt

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