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MiSTer, an open-source FPGA gaming project

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Re: MiSTer, an open-source FPGA gaming project

#71

Post by bstar77 »

vardump wrote: post #41
fooblat wrote: post #10

I love my MiSTer build! The usb controllers made for the recent mini systems (NES, SNES, Genesis, etc) make great accessories for the mister. Add a couple of usb arcade sticks and you can really play almost any classic retro games as it was meant to be played. And then there are all the classic computer cores even including the PDP-1!

Yup, same! Can wholeheartedly recommend it for those who want something between emulation and real hardware. The Amiga core is fun, AGA, 2 MB chip, 384 MB fast. It supports hard disk images, so you can do a hard disk based Workbench installation and load games and demos practically instantly (and safely exit to Workbench) using WHDLoad. Arcade cores are fun as well. Just like in childhood, but less hungry for quarter…

This whole setup is a game changer for me, I got a complete WHDLoad setup done in under 5 minutes after a bit of sleuthing on Internet Archive. Now I just need to get the proper cables to connect my Commodore 1084s.

Re: MiSTer, an open-source FPGA gaming project

#72

Post by vardump »

bstar77 wrote: post #71
vardump wrote: post #41

Earlier quoted context omitted.

Yup, same! Can wholeheartedly recommend it for those who want something between emulation and real hardware. The Amiga core is fun, AGA, 2 MB chip, 384 MB fast. It supports hard disk images, so you can do a hard disk based Workbench installation and load games and demos practically instantly (and safely exit to Workbench) using WHDLoad. Arcade cores are fun as well. Just like in childhood, but less hungry for quarter…

This whole setup is a game changer for me, I got a complete WHDLoad setup done in under 5 minutes after a bit of sleuthing on Internet Archive. Now I just need to get the proper cables to connect my Commodore 1084s.

Well, indeed, it literally is a game changer.

Re: MiSTer, an open-source FPGA gaming project

#73

Post by klodolph »

mikepurvis wrote: post #56
klodolph wrote: post #40

Earlier quoted context omitted.

Most game consoles don’t do any of this, though. The gamepad is polled by software. On the NES and SNES, the buttons are connected to a shift register (e.g. 4021). The CPU triggers a latch and then reads out the shift register one bit at a time.

This would be less about a user peripheral like the gamepad (which is obviously going to be read out exactly once per frame anyway) and more about getting subtle interactions between the CPU, memory/DMA, and specialized systems for graphics/audio correct. And not just correct after thousands of hours of work to smoke out the exact sources of specific title bugs, but correct essentially for free. See for example the t…

I don’t think that the FPGA based emulation will be “correct essentially for free”. The FPGA emulation itself is a lot more labor-intensive to create in the first place. In order to make it work equivalently to original hardware, you will need to accurately understand how the original hardware works, which is something you would need for software implementations too.

In general, software has a much lower cost of development than the cost of developing something for FPGA, and if you had something like a Verilog implementation of your emulator, it is not necessarily true that you need to run it on an FPGA—you can run it in software, or use it to verify a software implementation.

I think the real argument here for FPGAs is that some things are tricky to emulate with reasonable speed and accuracy in software. I don’t think the other arguments hold up—for example, arguments about latency—since the time scales involved are fairly generous (16ms to generate a frame of video).

Re: MiSTer, an open-source FPGA gaming project

#74

Post by klodolph »

blihp wrote: post #60
klodolph wrote: post #40

Earlier quoted context omitted.

Most game consoles don’t do any of this, though. The gamepad is polled by software. On the NES and SNES, the buttons are connected to a shift register (e.g. 4021). The CPU triggers a latch and then reads out the shift register one bit at a time.

Sure, and for hardware this old the FPGA could re-implement the CPU (which ran at <4MHz) and the shift register at almost the exact frequency (or whatever frequency is necessary to reproduce the original behavior) of the original as necessary. Then you can run the original software without modification and get much closer to identical behavior and performance characteristics with much lower resource utilization. Gran…

I don’t think reproducing the exact behavior here is necessary, useful, or even interesting. You could use a USB gamepad and get behavior that is close enough that humans can’t tell the difference.

Re: MiSTer, an open-source FPGA gaming project

#75

Post by [deleted] »

astrange wrote: post #65
bcrl wrote: post #23

Earlier quoted context omitted.

That's exactly what's happening. There are loads of projects going on right now decapping old chips and reverse engineering them. From old CPUs like the 6502 to the Amiga Alice chip. It's just a matter of time before most of the retro systems are fully reverse engineered and documented.

FPGA cores are based on CPU emulators, so they aren't more accurate than the emulator, and decapping a chip doesn't help. FPGAs are written in languages like Verilog that are still high-level and do some probably misguided tricks to make it look like you're programming them with a vaguely C syntax.

[deleted]

Re: MiSTer, an open-source FPGA gaming project

#76

Post by kbenson »

klodolph wrote: post #70
djmips wrote: post #43

Earlier quoted context omitted.

This was given as an example, not for you to straw man about the gamepad.

Don’t know what you’re getting at. You seem to have taken offense, and I think it’s because you misinterpreted what I wrote.

Your comment seemed to be positioned as a refutation of the prior comment (it could have been meant as an aside, but without something to indicate that it can be hard not to assume it's a counter). Unfortunately, if it was meant as a counter to the prior argument, countering just the example put forth does not actually address the argument put forth, so it it looks like a straw man argument itself (that is, addressing an example, even if it was presented by others, without making any attempt to address the position itself).

Re: MiSTer, an open-source FPGA gaming project

#77

Post by klodolph »

kbenson wrote: post #76
klodolph wrote: post #70

Earlier quoted context omitted.

Don’t know what you’re getting at. You seem to have taken offense, and I think it’s because you misinterpreted what I wrote.

Your comment seemed to be positioned as a refutation of the prior comment (it could have been meant as an aside, but without something to indicate that it can be hard not to assume it's a counter). Unfortunately, if it was meant as a counter to the prior argument, countering just the example put forth does not actually address the argument put forth, so it it looks like a straw man argument itself (that is, addressin…

> ... countering just the example put forth does not actually address the argument put forth ...

The particular example put forth was a good example, and it's worth responding to. If you can come up with a better example, I'd love to hear it.

My argument is that the timing of inputs and outputs to consoles is heavily quantized, which gives you a lot more freedom if you want to create an accurate software implementation--depending on whether your goals are to emulate existing games or serve as a platform for experimentation. For example, the NES has lots of "timing tricks" but they are internal to the console, and at the scales it takes to render a frame of video, you can do a lot of work in software.

From https://news.ycombinator.com/newsguidelines.html

> In Comments

> Please respond to the strongest plausible interpretation of what someone says, not a weaker one that's easier to criticize. Assume good faith.

Re: MiSTer, an open-source FPGA gaming project

#79

Post by inDigiNeous »

TillE wrote: post #16
Jorge1o1 wrote: post #5

I don’t really know much about game emulation so I was curious about what differentiates this FPGA game project vs traditional CPU emulation. From their github page [1]: >Traditional emulators on CPUs execute code sequentially. This is a tricky method of emulation because real hardware has many chips and all of them work in parallel...This requires a lot of CPU power to emulate even an old and slow retro computer. So…

byuu wrote a good article about this, unfortunately it's no longer available, but basically it should be self-evident that there's nothing inherently more accurate about hardware emulation. If you've actually decapped the original chips and duplicated them exactly in an FPGA, that's pretty cool. But otherwise it's just another approximation. The lower power requirements are nice, of course.

Unless you have seen MISTer running (especially on an fixed HZ old school CRT monitor) vs running that same thing emulated on on a modern cycle-exact emulator. The difference is really noticeable.

This might come down to the emulator also running on a modern OS, which cannot guarantee at all times smooth framerates, whereas a dedicated FPGA can promise you that it's not running much more than the actual core needed to emulate that system.

Especially on a 50/60Hz CRT monitor the difference and latency from the controller to pixels to screen is noticeably faster and stuff like scrolling the screen and sprites are buttery smooth, just like in the original hardware.

Re: MiSTer, an open-source FPGA gaming project

#80

Post by numpad0 »

drewblaisdell wrote: post #11
tediousdemise wrote: post #8

Earlier quoted context omitted.

The Analogue Pocket[1] is exactly this (albeit proprietary). Out of the box it recreates GB, GBC, and GBA using the Altera Cyclone-V platform. [1] https://www.analogue.co/pocket

I wonder, why is there no DIY Analogue Pocket-style MiSTer project? Is the DE10-Nano too large or inefficient for this?

I think it is because the motivations for retro console FPGA simulations are to play competitive action games sit down with highly accurate timings. “There is a 5 frames window after this triple input sequence” thing. Pocket gaming happens at much relaxed timings so less demands exist for low latency cycle accurate simulations.
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