Accuracy takes power: one man's 3GHz quest to build a perfect SNES emulator

http://arstechnica.com/gaming/news/2011/08/accuracy-takes-power-one-mans-3ghz-quest-to-build-a-perfect-snes-emulator.ars

by thehigherlife • 15 years ago

176 44 15 years ago

arstechnica.com

guan2• 15 years ago

This might be a lot easier on an FPGA.

AretNCarlsen• 15 years ago

Replicate each component of the original SNES hardware? That has been somewhat done: you can buy hardware clones of the SNES in many stores.

icefox3• 15 years ago

Citation needed, but pretty sure I heard of compatibility issus that the clones had.

guan2• 15 years ago

Yes, or replicate all of the original SNES hardware in one FPGA chip (and perhaps a few external passive components).

elliottcarlson• 15 years ago

The majority of the clones are using "NES On a Chip" or "SNES On a Chip" - they have the same issues as the original minimal requirements based emulators and are generally quite quirky.

Though it looks like at least one person is attempting to create a better one using FPGA: http://cegt201.bradley.edu/projgrad/proj2006/fpganes/

matthew-wegner• 15 years ago

As mentioned in other comments, some SNES cartridges themselves contain coprocessors and other hardware. A clone console doesn't need to do deal with this since you're still playing physical cartridges (versus pure software ROMs).

But clone systems do have issues with many games anyway...

wccrawford• 15 years ago

I agree. Plus, I think if the goal is really to 'preserve history', making chips that replicate the original hardware is a lot better (and more accurate) way than trying to software emulate it.

luu• 15 years ago

It is. I did a Sega system on an FPGA in 2003 as a one-semester senior design project. Using a modern HDL (bluespec, or something like the proprietary language my company uses internally) on current FPGAs, you could probably do a much higher level implementation in 1/10th that time.

An SNES would be much more annoying to do, but probably no more than an order of magnitude moreso, so I doubt it would take more than a semester, even for someone who'd never touched an FPGA before.

dmm• 15 years ago

> I did a Sega system on an FPGA in 2003 as a one-semester senior design project.

The article was about achieving extremely high compatibility by emulating hardware quirks. What advantage would an FPGA be? Easier synchronization?

exit2• 15 years ago

this makes me think of full brain emulation.

how far are we from an in silico silicon virtualization suite?

TheSOB88• 15 years ago

Very

gwern• 15 years ago

The best estimates I know of is Sandberg and Bostrom's 2008 Whole Brain Emulation Roadmap: http://www.philosophy.ox.ac.uk/__data/assets/pdf_file/0019/3...

And yes, this is pretty relevant - it demonstrates that perfect emulation is extremely expensive (in line with the critics of the idea of AI or brain emulation), but it also demonstrates how this doesn't matter in practice. (eg. I'd be happy to be a nigh-immortal upload if the price was a few glitches in an obscure memory I never think about.)

exit2• 15 years ago

thanks for that link - very interesting.

i think the question in my post has been misunderstood. i'm wondering, when will it be possible to simulate a SILICON device - such as the super nintendo.

instead of emulating the functional profile of the snes, we could run a physics simulator (at some level of abstraction) that contains all of the silicon circuitry and so forth which actually produces the functional profile.

that seems like a milestone towards simulating neural "devices" like the human brain.

blhack• 15 years ago

http://en.wikipedia.org/wiki/Blue_Brain_Project

ansy• 15 years ago

This is very interesting. As the article states, most SNES emulators are inaccurate by quite a bit. Despite that the incompatibilities are mostly imperceptible. Perfect emulation of the brain and human intelligence may be a long way away. But perhaps something very closely resembling it is not nearly as far off as we think.

lscharen• 15 years ago

I've been follow Byuu's progress on BSNES for a couple of years, and I would like to state for the record that the amount of effort he had put into this project far exceeds the majority of "hobby" projects.

Just in the past few months, several SNES co-process chips that remained un-emulated for years, have been deciphered and fully emulated in BSNES. Without Byuu leading the charge into the last bastions of SNES emulation, I absolutely believe that some of these devices would be lost to history.

joelhaus• 15 years ago

You would think that the OEM's are leaving a fair amount of money on the table by not offering a true software emulator.

Have you heard of anyone from Nintendo getting involved (in a positive or negative way) with Byuu's project (or maybe they already offer one via the Wii--not sure)?

T-R3• 15 years ago

Nintendo offers the "Virtual Console" on the Wii and 3DS.

Unless my knowledge is out of date, Nintendo's business model revolves around licensing for publishing software for their hardware, so it's in Nintendo's best interest to sell hardware, and not to support emulation on other hardware.

On a related note, when Sony sued 'Bleem!', it argued that running the software on other hardware destroyed Sony's control over the player's experience, and as a result hurt their brand.

icefox3• 15 years ago

For anyone who is looking for some code to read with I would recommended BSNES. It isn't a huge code base and worth the trip. Read through most of it last year after finding it and found it most enjoyable.

tedunangst• 15 years ago

I wonder if such accuracy is necessary for emulating newer systems. I don't think my PS3 games are updating the graphics hardware mid-scanline. If modern systems have more relaxed timing requirements, then a much simpler binary translation may be enough. You no longer have to model the hardware, just the abstraction layer that the game itself is written against.

T-R3• 15 years ago

This was indeed the case as early as the N64 - the technique was referred to as High Level Emulation (HLE).

http://en.wikipedia.org/wiki/UltraHLE

daeken4• 15 years ago

This is the premise of HLE, or high-level emulation. You emulate the CPU (if it doesn't match the current one), and then implement all the APIs it hits. It's more like WINE than BSNES.

The one place where you may end up emulating something with precise timing is the audio processor; the Gamecube and Wii for instance used a custom DSP that had to be emulated fairly precisely, after the instruction set was revere-engineered.

YooLi• 15 years ago

"One of the fun aspects of a cartridge-based system is that you are literally plugging a PCB directly into your system. Thus, you can put extra coprocessors, often digital signal processors, right inside of the cartridge. This gives you an extra edge against your competitors' titles. The most popular SNES coprocessors were the SuperFX for polygon rendering and sprite rotation (used in Starfox and Super Mario World 2) and the DSP-1 for 3D math (used in Pilotwings and Mario Kart.)"

Very interesting. I never thought about this even though I've recognized the differences between games. I just attributed it to better game software, but it could literally have been better hardware available to certain games. You can't do that with CD/DVD/downloadable games.

daeken4• 15 years ago

This is why the NES had the insanely long life it did. Every game was able to provide custom hardware (called 'mappers') to offload computation. I've said for a while now that the next generation of consoles will go one of two routes: completely downloadable titles, or PCI-e-based cartridges. I'm inclined to think the latter, despite the evidence to the contrary. It's just such a huge benefit, and they love shipping physical items. This would also largely eliminate piracy.

RainFlutter• 15 years ago

A general system expansion slot would make a lot more sense. Think the RAM expansion on the N64. It'd be silly for each new game to have to provide its own extra processors or RAM in its own (expensive) cartridge, and console piracy is close enough to dead already.

ericd3• 15 years ago

The cost savings of downloads are just too ridiculously huge to really think about going back to manufacturing circuit boards. Beyond the marginal circuit board cost, there's a huge physical goods infrastructure that just doesn't have to exist when you go with downloads. Servers are a good bit easier to manage than manufacturing plants and shipping infrastructure.

kindlyviking• 15 years ago

I'm really impressed by the dedication of this guy. Kudos.

Someone• 15 years ago

A similar (and IMO, better written) story on emulating the TRS-80: http://queue.acm.org/detail.cfm?id=1755886

Accuracy takes power: one man's 3GHz quest to build a perfect SNES emulator

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