If you want to eg add original ports and hardware interfaces that tends to be easier with an fpga: cartridges, midi etc. Of course you can do that in software/

If you want to eg add original ports and hardware interfaces that tends to be easier with an fpga: cartridges, midi etc. Of course you can do that in software/ bit bang. Though it’s complicated by emulator timing, they tend to run frame by frame and sync at the end of a frame.