MiSTer FPGA Forum

aberu wrote: ↑Wed Apr 28, 2021 3:40 pm Exactly right. I think for those systems and later a "baremetal emulator" as they can be called would probably be the optimal way to achieve low input latency emulation of these systems.

My second Spectrum emulator was as low-latency as software can possibly be. The only thing it didn't do was produce 50 Hz video; my plans on this had to be cancelled as Windows started to dominate and DOS started to fade. But for the rest, DOS acted as a thin layer over what was basically a baremetal machine.

The low latency was achieved due to the fact that it directly accessed hardware, both audio and keyboard, and did so at the exact time that the emulated software required it, thanks to precise timing via the RDTSC Pentium instruction. With more modern OSes that would not be possible at all. Of course, emulating DOS does not really cut it; the low latency is spoiled by the hardware abstraction layers.

But a purposefully designed baremetal machine is a really appealing idea with the potential of bringing back that power that I once had with DOS, to the current world. Have direct access to audio, video, keyboard and high resolution clock with one CPU or core, while another takes care of OS stuff like USB, storage and the like.

Yeah, old emulators written in Assembly (Bleem! as well) were excellent but then you would get a new generation of Windows and processors and it wouldn't work anymore, so I get why people stopped coding them that way.

I know this is veering off-topic, but emulation accuracy is generally a function of how close to the hardware you are, and whether there are any critical sections which require more instantaneous power than your CPU can provide.

It's becoming possible again to have decent no-lag emulation again, on trivial 'computers', which can directly access I/Os at high speed.

Check this out:
https://www.hackster.io/news/graham-san ... 4c078a6a9a

I wonder why people keep saying that consoles beyond the PS1 are easy to emulate in software, and that FPGAs aren't necessary for this task? PS2, Dreamcast, Gamecube and Wii are all emulated pretty poorly today, with lots of glitches, performance all over the place, game-specific hacks, dynamic recompilers, shader caches, and so on.

If anything, the state of software emulation of newer consoles seems to indicate an even greater need for FPGA hardware. Emulators like Snes9x were already in a pretty good state around 20 years ago. But this is just my observation as a user and tester.

The explanation is as follows - in older devices, every cycles counted, and interlock issues between discrete pieces of software were a common occurrence; if you "miss the window" for update, there would be a long delay before the window would reopen, and timing issues could happen, in nearly every case being visible.

For more modern consoles, the number of cycles taken by a high-level operation is very high, and being "off" by a couple of cycles is more like 1-in-a-million than 1-in-10. Software also isn't written to rely on timing quite as much.

The issues you are seeing in emulation of more modern consoles don't stem from these timing-related issues; rather, they stem from incomplete understandings of the hardware (or incomplete implementations). Reimplementing on a FPGA won't fix this - more reverse-engineering data will though.

dshadoff wrote: ↑Fri Apr 30, 2021 11:56 pm The issues you are seeing in emulation of more modern consoles don't stem from these timing-related issues; rather, they stem from incomplete understandings of the hardware (or incomplete implementations).

It also stems from differences in hardware and APIs between the target platform and the original hardware. There isn't always an easy 1:1 way to implement.

These are all issues that can be worked through but they take manpower, someone has to be motivated to do the work.

softtest9 wrote: ↑Fri Apr 30, 2021 10:34 pm I wonder why people keep saying that consoles beyond the PS1 are easy to emulate in software, and that FPGAs aren't necessary for this task? PS2, Dreamcast, Gamecube and Wii are all emulated pretty poorly today, with lots of glitches, performance all over the place, game-specific hacks, dynamic recompilers, shader caches, and so on.

If anything, the state of software emulation of newer consoles seems to indicate an even greater need for FPGA hardware. Emulators like Snes9x were already in a pretty good state around 20 years ago. But this is just my observation as a user and tester.

PCSX2, Dolphin, Flycast, will all disagree with you. And when you consider the price of a De10, how much would an FPGA cost that could manage anything more complex like a PS2 ?
We are in no shortage of newer consoles, most of them originally sold millions, so it's not like they need preserving, or there is a lack of them around.
And at what stage does it go from preservation and accuracy, to piracy ?

PCSX2 and Flycast are the exact examples I would cite for being hacky, glitchy, and incomplete. These consoles are incredibly complex and the PS2 "GPU" hardly resembles modern GPUs so what they've achieved is incredible, but there are still severe deficiences in accuracy. Not that FPGA would be any kind of a magic fix for this situation.

Dolphin has been pretty accurate but the main struggle there is brute-forcing realtime shader compilation. Not to mention getting a good non-laggy interface for wiimotes.

I would hardly call PCSX2 hacky and glitchy. Ok, some games have been problematic - I remember how long the Jak series had rendering problems when using a hardware renderer, such as Jak's eyes. But the PS2 did things that just wasn't/isn't possible with PC hardware, so some sort of middle-ground had to be made by the devs. I mean, I can fire-up most of the best PS2 games, such as Gran Turismo 4, at 4k + all the usual shader bells and whistles to make the game look amazing when you consider how old the game is. That is not a hacky, glitchy emulator, that is an emulator that, while there are still some issues, is one of the best emulators out there. And no longer do you need a few hundred specifically made ini files to run games, most games now run on stock settings. Infact, I believe they have removed almost all hacks now.
Flycast, ok it's far from perfect, but it runs games so well I doubt there are many out there that would see the emulator as a laggy, glitchy mess.
As for Dolphin, surely this now runs even on a potato PC ? It's such a mature, well-developed emulator with little problems remaining. And again, at 4k res this still looks amazing.

MiSTer_Kirk wrote: ↑Sat May 01, 2021 7:54 pm But the PS2 did things that just wasn't/isn't possible with PC hardware, so some sort of middle-ground had to be made by the devs.

That's what we're saying though. It's not the devs' fault. There just isn't enough CPU power to emulate a console like the PS2 accurately and get more than 1 or 2 fps even on current enthusiast hardware. Software emulators that are fullspeed _and_ accurate, aren't really a thing beyond the 32/64-bit era. Future FPGAs may or may not be a solution to this problem.

MiSTer_Kirk wrote: ↑Sat May 01, 2021 7:54 pm I mean, I can fire-up most of the best PS2 games, such as Gran Turismo 4, at 4k + all the usual shader bells and whistles to make the game look amazing when you consider how old the game is.

MiSTer_Kirk wrote: ↑Sat May 01, 2021 7:54 pm And again, at 4k res this still looks amazing.

Artificially increasing the rendering resolution is a hack. Hardware renderers are a hack. Changing how the system is emulated on a per-game basis, to get around problems like how the PS2 has a different floating point format, compared to x86 PCs, is a hack. Being able to play the most popular games is not a good measure of accuracy either.

It's totally fine if you prefer inaccurate emulation, but at least be honest about it please.

Artificially increasing the rendering resolution is a hack. Hardware renderers are a hack. Changing how the system is emulated on a per-game basis, to get around problems like how the PS2 has a different floating point format, compared to x86 PCs, is a hack. Being able to play the most popular games is not a good measure of accuracy either.

I don't think you know what a hack is.

It's totally fine if you prefer inaccurate emulation, but at least be honest about it please.

Total, and complete and utter elitist snobbery at it's best.

softtest9 wrote: ↑Sat May 01, 2021 9:30 pm

MiSTer_Kirk wrote: ↑Sat May 01, 2021 7:54 pm But the PS2 did things that just wasn't/isn't possible with PC hardware, so some sort of middle-ground had to be made by the devs.

That's what we're saying though. It's not the devs' fault. There just isn't enough CPU power to emulate a console like the PS2 accurately and get more than 1 or 2 fps even on current enthusiast hardware. Software emulators that are fullspeed _and_ accurate, aren't really a thing beyond the 32/64-bit era. Future FPGAs may or may not be a solution to this problem.

I don't think that it's because "there isn't enough cpu power". It's because true cycle accurate ps2 emulation is exceedingly difficult to ever accomplish because it is a very complex system. The Dreamcast and Gamecube are probably easier despite being faster systems. If the current PS2 emulators were developed from the ground up to be cycle accurate and they did similar painstaking performance optimizations like byuu did with bsnes in the last 2 years of him developing that emulator, I doubt you would see performance issues on enthusiast hardware.

Part of the other problem with it being complex is... it's a pain in the ass to develop an emulator for it relative to others. So PCSX2 took over a decade and it's code is old and probably needs to be cleaned up and refactored for performance.

MiSTer_Kirk wrote: ↑Sat May 01, 2021 10:13 pm

Artificially increasing the rendering resolution is a hack. Hardware renderers are a hack. Changing how the system is emulated on a per-game basis, to get around problems like how the PS2 has a different floating point format, compared to x86 PCs, is a hack. Being able to play the most popular games is not a good measure of accuracy either.

I don't think you know what a hack is.

It's weird for them to call it a hack, but I think I know what they mean. Hardware renderers, as far as I know having kept up with this for awhile, can't really be cycle accurately (or at least aren't currently) used for ps2 emulation. In terms of the PS1 emulation at least, the hardware renderer in mednafen is a mess. Look at the water in the opening scene of Metal Gear Solid and compare between software renderer and hardware renderer. I think what they mean as far as a hack is probably that it's a "workaround" to get better performance.

They are definitely correct about how the current state of PS2 emulation requires actual exceptions using high-level emulation just to make plenty of games work. There is no real cycle-accurate PS2 emulator after all these years of development. They are a mesh of low-level and high-level with varying degrees of accuracy to the end user, but most games still have minor bugs and some have major bugs. Fire up Valkyrie Profile 2 as an example, plenty of the graphics effects have major bugs. Audio in a good number of games still have problems either in sync, or in loops, etc...

And they are 100% correct about the floating point imprecision issue.

https://github.com/PSI-Rockin/DobieStation/issues/51

DobieStation is (aside from games supported) the most accurate PS2 emulator in terms of behavior, and the softfloat approach mentioned here supposedly would make things too slow. I'm still not convinced, but it is what it is.

I think people are overestimating how much is properly understood about those chips in later-generation machines.
We're still learning things about the chips in machines from the 80s. Even if you know 99% and can run most games, there will be some weird glitch that isn't understood until that final 1% is understood.

dshadoff wrote: ↑Mon May 03, 2021 2:30 pm I think people are overestimating how much is properly understood about those chips in later-generation machines.
We're still learning things about the chips in machines from the 80s. Even if you know 99% and can run most games, there will be some weird glitch that isn't understood until that final 1% is understood.

Oh absolutely agreed on this. Let alone the problems of having a 128-bit system running in FPGA

It's weird for them to call it a hack, but I think I know what they mean. Hardware renderers, as far as I know having kept up with this for awhile, can't really be cycle accurately (or at least aren't currently) used for ps2 emulation. In terms of the PS1 emulation at least, the hardware renderer in mednafen is a mess. Look at the water in the opening scene of Metal Gear Solid and compare between software renderer and hardware renderer. I think what they mean as far as a hack is probably that it's a "workaround" to get better performance.

But you can't call a resolution change, a hack. Otherwise, ALL emulators are now hacks, which is just silly. I mean, it simply isn't possible to run these old systems at their original resolution, and refresh rate, on a modern PC and display, modern monitors don't go down to such a low resolution. So, you either run them in a really tiny window, or you run them at multiples of their original resolution, or as close to them as your display will get.
But also, because of all the power we now have, we can improve those systems way beyond their original design. Really high resolutions, modern shaders to improve the graphics, modern techniques to actually add to the hardware to improve it - such as the Playstation's infamous wobbly textures due to a lack of a Z-buffer, so we now have PGXP. To me, this isn't a hack, it's a feature. We can now overclock the host CPU, fast-load tape loading so it's now instant loading. Play with almost any controller, no more of those old cheap crappy 80s joysticks, we now have modern USB arcade sticks/controllers.

There is way too much FPGA snobbery in these forums, and I think it's a little unfair when emulation, which we've ALL benefitted from over the years, continually gets a kicking from the FPGA snobs. I personally prefer many systems on my PC, such as MAME, simply because it's not only so damn easy to just sit here and select a game, but I also have thousands of arcade games to play, not a handful on the Mister. Then we have Misters cores that still are not as good, or accurate as emulation. Disk controllers missing, so we have the god-awful MMC, or VHD ways of playing games. Some cores still not behaving right, such as poor/weird sound issues, or speed problems on some arcade cores.
Don't write the Pi off just because it's a Pi. Connected to a CRT, running the systems at their original resolutions, not many here would tell the difference between a Pi and the Mister for 8-bit systems. 16-bit systems, maybe, especially the SNES where the Pi can't run the more accurate BSNES core. Also, the Pi can run a fully kitted-out Amiga system far better than the Mister - even with the new hybrid mode. Especially PiMiga, a Raspberry Pi 400, with it's own keyboard, and mouse, and a pre-made image all setup to go - this blows away anything the Mister has so far. And the Pi community if far bigger than the Mister community.

I don't think that it's because "there isn't enough cpu power". It's because true cycle accurate ps2 emulation is exceedingly difficult to ever accomplish because it is a very complex system. The Dreamcast and Gamecube are probably easier despite being faster systems.

I don't entirely disagree with this. But I think that complexity also impacts performance requirements. That's why for example mednafen needs a significantly beefier PC to emulate the Saturn, than it does to emulate the PS1, even though the two consoles are fairly similar in what they can do. Accuracy also tends to correlate with higher system requirements like in the example with the PS2's floating point format.

Another example is the dual core hack in Dolphin. It's a very important feature, performance-wise, but it also breaks some games (e.g. Sonic Adventure 2 Battle will randomly crash with it enabled).

Pretty often I read from PCSX2 and Dolphin developers saying something along the lines of "We know how to fix this problem, but doing so would murder performance, so we're going to settle for a hack for now."

So yeah, I don't disagree that there is a lot of missing information, but I think that CPU power is an almost bigger, if not bigger, issue.

But you can't call a resolution change, a hack. Otherwise, ALL emulators are now hacks, which is just silly. I mean, it simply isn't possible to run these old systems at their original resolution, and refresh rate, on a modern PC and display, modern monitors don't go down to such a low resolution. So, you either run them in a really tiny window, or you run them at multiples of their original resolution, or as close to them as your display will get.

This is apples and oranges. You can take a real SNES, connect it to a Framemeister or an OSSC, and have a 1080p or higher output going out to your TV or monitor. That is of course _not_ a hack. It doesn't change how the console functions internally.

In the same way, most 2D console emulators will have the same resolution internally as the real console, and they will only apply upscaling as a post-processing step. This method is accurate. On the other hand, there is now a feature introduced by bsnes-hd, where the actual internal rendering resolution is changed to make the Mode 7 effect look better. That is a hack. Whether that is good or bad is subjective. I find the feature quite enjoyable, but I also appreciate that I can turn it off if it makes a game glitch too much.

But also, because of all the power we now have, we can improve those systems way beyond their original design.

Yes and that's great. I love playing around with those features. But usually I will turn them off at some point because they introduce various glitches that annoy me more than the original hardware's flaws.

To me, this isn't a hack, it's a feature.

Hacks _are_ features, otherwise they wouldn't be added in there. But every feature has a side-effect. It's all a trade-off.

There is way too much FPGA snobbery in these forums,

I don't see any "FPGA snobbery" in this thread or forum. I for one use software emulators pretty frequently, even inaccurate ones. Inaccurate emulation is better than none at all, and just about every emulator or FPGA core author has learned from other projects that already existed. It's just that when given a choice, some of us prefer the most accurate solution with the most predictable performance.

But this stance isn't enough for some people. Instead you have to pretend that inaccurate emulators are perfect, because the "best" games "look beautiful in 4K", and pretend that FPGAs don't have _any_ benefits over a typical PC whatsoever. That to me is ridiculous.

and I think it's a little unfair when emulation, which we've ALL benefitted from over the years, continually gets a kicking from the FPGA snobs.

Just what are you talking about? Every MiSTer user that I've come across is also a fan of software emulation.

I don't see any "FPGA snobbery" in this thread or forum. I for one use software emulators pretty frequently, even inaccurate ones. Inaccurate emulation is better than none at all, and just about every emulator or FPGA core author has learned from other projects that already existed. It's just that when given a choice, some of us prefer the most accurate solution with the most predictable performance.

But this stance isn't enough for some people. Instead you have to pretend that inaccurate emulators are perfect, because the "best" games "look beautiful in 4K", and pretend that FPGAs don't have _any_ benefits over a typical PC whatsoever. That to me is ridiculous.

So, you don't see any FPGA snobbery, but then go on to post "Inaccurate emulation" as if ALL emulation is inaccurate, it isn't.
And where did I post that FPGAs don't have ANY benefits ? Now you are just making crap up.
Also, I do find it rather funny that some here find emulation inaccurate, only to go on and connect their misters to a modern LCD display. Ok, so the Mister is producing an accurate simulation of the real thing, but to then go on an run the Mister at 1080p/1440p etc.. on a display the original hardware wasn't intended for. That, is rather hilarious. If emulators running at 4k is a hack, then what is the Mister running at 4k ?

but then go on to post "Inaccurate emulation" as if ALL emulation is inaccurate,

Nope. There are quite a few accurate emulators, just not so much when you get to Dreamcast and beyond. And there is no FPGA core implementing such consoles either.

If emulators running at 4k is a hack, then what is the Mister running at 4k ?

Taking a 240p image and scaling it to 4k is not a hack. Changing how the graphics chip is emulated internally, so that this upscaling doesn't even need to happen, is a hack. Doesn't matter if it's FPGA or software emulation.

justaguy wrote: ↑Wed Apr 28, 2021 3:38 pm If Dreamcast and up wouldn't really benefit from FPGA emulation, would a hypothetical "MiSTer but for more advanced consoles" really need to be FPGA-based?

it’s called a PC. you can build them in small form factor these days and they have the advantage of the emulators running on them having often had decades of performance tuning and debugging.

see: the new atari VCS. it’s a small form factor pc.

throAU wrote: ↑Mon May 03, 2021 10:26 pm

justaguy wrote: ↑Wed Apr 28, 2021 3:38 pm If Dreamcast and up wouldn't really benefit from FPGA emulation, would a hypothetical "MiSTer but for more advanced consoles" really need to be FPGA-based?

it’s called a PC. you can build them in small form factor these days and they have the advantage of the emulators running on them having often had decades of performance tuning and debugging.

see: the new atari VCS. it’s a small form factor pc.

This is best for today's emulators for sure. But there definitely could be real advantages to baremetal emulators running in real mode on a platform with very well documented hardware. There's too much abstraction between the emulator and the hardware on modern operating systems and closed sourced drivers obfuscate how the hardware actually works.

The VCS runs linux with 100% open drivers.

The problem with a bare metal emulator is effort. You’re going to need to learn the intricacies of modern PC hardware and its simply far too complex for most individuals to understand. Even AMD/NVIDIA have problems getting decent GPU drivers out for their own hardware for a long time - and they have dedicated, paid teams working on it

And you’re going to need to do much of the stuff the OS does anyway to host your emulator. Sure, you can write your own scheduler to very specifically cover your use case, but you may well still be better off with an extremely stripped down linux distribution and just writing your own scheduler / virtual devices for that.

Even the late 90s and on consoles didn’t require programmers for the native platform to program the hardware directly. The dreamcast for example offered DirectX via Windows CE built into it, if the programmer wanted to use that. Sega Rally 2 for example was written using the included Windows CE support.

So for more modern consoles you just neeed to emulate the console’s APIs that the software was written for, not the hardware. If you emulate the APIs fast enough, the hardware implementing them is irrelevant. Just like no PC game cares for example whether you’re on an NV20 GPU, it just cares that the driver does OpenGL or Direct3d fast enough.

Taking a 240p image and scaling it to 4k is not a hack. Changing how the graphics chip is emulated internally, so that this upscaling doesn't even need to happen, is a hack. Doesn't matter if it's FPGA or software emulation.

Original hardware don't have 4k scalers, if you connect original hardware to a fancy 4k OLED TV then the resolution will be native, and the TV will do the scaling. On a Mister, the display isn't doing the scaling, the Mister is. So, if emulation running at 4k is a hack then so is the Mister.

If THIS, isn't a hack...

dvi_mode=8

For 1080p scaling on the Mister, then neither is this...

resolution = 1920x1080

in any emulator's ini file. If the Mister is scaling up the image, then so are the emulators. You can't say one is scaling, while the other is a hack.

So, if emulation running at 4k is a hack then so is the Mister.

No core is "running at 4k" or "running at 1080p". The core runs at 240p or whatever the console is designed for. Then the MiSTer's scaler upscales the image as a post-processing step. Emulators of 2D consoles generally work the same way. The emulated console is rendered at the original resolution, and then the final output gets upscaled by the emulator's user interface.

This has _nothing_ to do with increasing the rendering resolution, which is what a lot of hardware renderers do for emulators of 3D consoles.

You can't say one is scaling, while the other is a hack.

Correct. Nobody is saying that.

You are either a troll or you have serious problems with reading comprehension.

If raspberry pi's and other SBC's keep getting more powerful, we'll probably see the day where a future rPi compute module can be paired with an compatible FPGA development board to work in a similar way to how the DE10-Nano interfaces with its ARM side, but with the increased power on the ARM side probably be capable of hybrid emulation maybe even up to the N64, maybe even the Gamecube and Wii. Perhaps in several years from now.

You are either a troll or you have serious problems with reading comprehension.

You're an idiot.

A universal software emulator would look like a lopsided PC: CPU with extremely fast single-threaded performance and at least a second core for housekeeping chores, and a GPU that can do both 2D in wonky resolutions as well as good 3D and output it all through every type of port from ancient analogue monochrome to the latest DisplayPort. RAM would be far less important. Low latency IO pins for controller interfacing and a generous amount of GPIO for misc add-ons and some fast interconnect like PCI(e) for integration of the device into even bigger constructs would round it off for me. Adding an FPGA into that mix could prove to be very interesting.. But as it stands now, such a system is mostly just a pipe dream.

MiSTer_Kirk wrote: ↑Tue May 04, 2021 1:00 amIf the Mister is scaling up the image, then so are the emulators. You can't say one is scaling, while the other is a hack.

You're missing something here--emulators for N64, Playstation, Wii, etc. can alter the internal rendering resolution and actually run the game at native 1080p or 4k or whatever, plus they can load in HD texture packs. Completely separate from scaling native render resolution.

throAU wrote: ↑Mon May 03, 2021 10:26 pm

justaguy wrote: ↑Wed Apr 28, 2021 3:38 pm If Dreamcast and up wouldn't really benefit from FPGA emulation, would a hypothetical "MiSTer but for more advanced consoles" really need to be FPGA-based?

it’s called a PC. you can build them in small form factor these days and they have the advantage of the emulators running on them having often had decades of performance tuning and debugging.

see: the new atari VCS. it’s a small form factor pc.

Don't get me wrong, I'm not the kind of guy who turns up his nose at PC emulators just because they're "software emulation". It's just that I find the experience of setting them up, keeping them updated, and just about everything besides actually playing a game (which to be fair is the most important part) to be so much worse than MiSTer. If there were a Linux-based emulation frontend with a MiSTer-like UX, but which supported emulators for systems that MiSTer could never run, I'd be all over that.

justaguy wrote: ↑Tue May 04, 2021 6:16 pm

throAU wrote: ↑Mon May 03, 2021 10:26 pm

justaguy wrote: ↑Wed Apr 28, 2021 3:38 pm If Dreamcast and up wouldn't really benefit from FPGA emulation, would a hypothetical "MiSTer but for more advanced consoles" really need to be FPGA-based?

it’s called a PC. you can build them in small form factor these days and they have the advantage of the emulators running on them having often had decades of performance tuning and debugging.

see: the new atari VCS. it’s a small form factor pc.

Don't get me wrong, I'm not the kind of guy who turns up his nose at PC emulators just because they're "software emulation". It's just that I find the experience of setting them up, keeping them updated, and just about everything besides actually playing a game (which to be fair is the most important part) to be so much worse than MiSTer. If there were a Linux-based emulation frontend with a MiSTer-like UX, but which supported emulators for systems that MiSTer could never run, I'd be all over that.

There is. It's called attract-mode. I created a layout that has inspiration from the neogeo unibios picknmix. Works perfect at 240p on crt as well as a high resolution lcd. It wouldn't be hard to create one that looks like the mister.

Devs will just continue to make the cores available better. There are still plenty of things that can be implemented on MiSTer. I never expected MiSTer to go beyond say PS1 anyways. I'm actually really excited and happy with all the recent improvements on the C64 core.