We wanted to play Mario on the NES but couldn't, so we wrote an emulator for the NES on our own -- or tried to, anyway. This is an abridged version of OneLoneCoder's tutorial on a complete NES emulation, implemented and tested for the MOS 6502 chip aboard the original NES.
The snapshot below captures our emulator using the OLCPixelEngine to blit a live-feed of the emulation process.
Note that While we have a functioning Picture Processing Unit too, we were not able (yet) to connect the PPU to the cartridge, which is how sprites are blitted onto the screen.
In essence, each peripheral of the NES is to be thought of as an object connected to the Bus, which as most online resources rightly call, is the heart of the architecture of the NES.
We have emulated the processor (the ’6502), the PPU (the ’2C02), as well as the general functioning of the cartridges and the different kinds of RAM accessed by the bus during the working of the NES. Right now, our emulator can output to some degree of accuracy the functioning of the processor when given a .NES file, which is essentially a dump from a physical NES cartridge. We have tested it out with the NES testing suite, and our results corroborate well with the sources that we referred to. We believe our emulation is acccurate.
Paired with a disassembler function, our project is a good way to look at actual programs from the 1980s and see how they were written and structured.
The project would not have been possible without OneLoneCoder’s PixelGameEngine, which is an open-source tool that we used to display our emulated data on the screen.