runahead is brilliant but it relies on save states being trivially fast to create, which isn't broadly true especially as you get to newer & newer consoles. And strictly speaking needs to be adjusted on a per-game basis as it really depends on the game's internal latency in responding to button presses.
But that also doesn't necessarily offset the latency of getting inputs into the emulator in the first place or in getting video frames from the emulator to the display.
FPGA doesn't really solve your other two issues, nor is it practical for anything post-PlayStation/Saturn/N64, so those objections are not very strong. Past that point the games are designed more with a certain amount of lag in mind anyways.
Are you arguing from a theoretical or practical standpoint? In practical cases the FPGA products do solve my first two issues, as the video output path of the emulation goes directly to the display output in the FPGA. Meanwhile in all software-based emulation products, the video output path goes through a normal Linux graphics stack, which tends to be crap (and not getting better with the silly X11 vs. Wayland fight that keeps Linux's graphics stuck in a bad spot).
That's not an inherent limitation of software emulation, no, but for all practical purposes it is as nobody is doing specialized software emulation for a specific set of hardware to bypass the normal OS/graphics stack. It's instead "throw linux on it, and fullscreen an off the shelf emulator"
> FPGA doesn't really solve your other two issues, nor is it practical for anything post-PlayStation/Saturn/N64
I agree with most of your point here, bus is that particular one true? Doesn't the Gamecube (for example) use a PowerPC chip? I would be very surprised if isn't an effort to make FPGA implementations of the PowerPC.
I realize that there's a lot more to making a clone system than "just recreating the CPU", but why would making an FPGA for something after the N64 be impractical?
As I understand it, the hardware they’re using isn’t up to the task and it would be prohibitively expensive. The complexity is also greater but perhaps that isn’t insurmountable.
I don't know a lot about FPGAs, but I guess I just assumed that they're like basically everything else in tech where they get cheaper and better as time goes on. If that's correct then I don't see why we couldn't have a GameCube or Xbox clone system eventually.
I think this might be more important as time goes on as well. Getting cycle-accurate emulation of anything more complex than the Dreamcast I think will become pretty prohibitive to do in-software. I suspect something like CEN64 might end up being the last cycle-accurate emulator out there (though I would absolutely love to be wrong on that). The advantages of FPGAs would make themselves substantially more apparent at that point than the Gameboy or NES.
But that also doesn't necessarily offset the latency of getting inputs into the emulator in the first place or in getting video frames from the emulator to the display.