Nestopia is a portable open source NES/Famicom emulator written in C++. It's designed to be as accurate as possible and supports a large number of peripherals. The hardware is emulated at cycle-by-cycle granularity, ensuring full support for software that do mid-scanline and other timing trickery. The emulation core has been carefully made to conform to the C++98 standard and any decent compiler should be able to compile it without any hassle. To ease the process of porting the emulator to a platform of choice, the core provides a set of API classes.