[tombert]

I remember that post; Byuu conceded that FPGAs will always have an edge latency-wise, but was really annoyed that people acted like FPGA magically made things "more accurate" than something like bsnes, saying FPGAs can still be subject to the same bugs or mistakes as emulators, and are harder to develop. I got the impression that Byuu did not like the Analogue people very much.

[matheusmoreira]

Hardware emulation is also just as impenetrable as the original systems themselves. Software emulation serves as documentation for the hardware and is therefore much better at preserving that knowledge.

[emodendroket]

You could look at the Verilog/VHDL/whatever they use, right? Either way the source code has to be available for it to be useful in that way.

[monocasa]

Sticking another emulator under a decompiler is probably at least a couple orders of magnitude easier than looking at an FPGA bitstream. Particularly for the kinds of people who hack on emulators.

[emodendroket]

With all the stuff like runahead and frame delay showing up in Retroarch I'm not convinced that the latency thing is even true except if we're confining ourselves to low-powered devices.

[tombert]

Yep, actually in my only interaction with Byuu (RIP) they were explaining emulator runahead to me, and they seemed really excited about it, saying that it had the potential to have even lower latency than official hardware.

That said, I will concede that there is definitely an audience for low-power devices obviously, and maybe FPGAs will fill that niche.

[kllrnohj]

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.

[emodendroket]

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.

[kllrnohj]

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"

[tombert]

> 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?

[emodendroket]

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.

[tombert]

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.