MiSTer FPGA Forum

Can't seem to find any info on a saturn core.

That's because there isn't one

The Saturn was a pretty complex system with tons of different processors. Regardless of whether it'd be techinically feasible to implement it on the MiSTer, it would probably require an absurd amount of work. So I can see why people would find it daunting to begin working on a Saturn core even if they have the skills for it.

It would be awesome if it happened someday, but I wouldn't hold my breath.

All of what mic_ said, basically.

People sometimes exaggerate Saturn's complexity to the point that it sounds like an utterly unfathomable beast of a system, but it is genuinely pretty complex. You have:

• Two SH-2 CPUs
• 68K (as a sound controller)
• SCSP synthesis/sample engine (Yamaha, but odd, i.e. not just an OPL3/4 core)
• SCSP DSP
• SCU DSP (custom DSP embedded into the "chipset")
• Miscellaneous SCU functionality ("B bus" interface/arbitration, DMA, timers, interrupt control)
• VDP2 (background generator)
• VDP1 (sprite/polygon engine; rasterizes quads rather than triangles, which causes quirks because quads can be concave)
• CD block (SH-1 ROM microcontroller + CD drive interface; I think someone dumped the firmware for this, otherwise a compatible interface would need to be written either for an MCU core or on the Linux side)
• Main RAM split between asynchronous and synchronous banks (CPU vs. SCU access; a little bit like Amiga "chip RAM" vs. "fast RAM")
• General access width/alignment weirdness arising from bus width differences among the various components

Of the various components, the only ones that really lend themselves to reusing an existing core are the SH-1/2 and 68K. Everything else is custom.

The system the Saturn does share a fair bit with is the 32X, but it is also bit of a beast and has it's own weird esoteric aspects.

"The 32X contains two Hitachi SH2 32-bit RISC processors with a clock speed of 23 MHz,[3] which Sega claimed would allow the system to work 40 times faster than a stand-alone Genesis.[1] Its graphics processing unit is capable of producing 32,768 colors and rendering 50,000 polygons per second, which provides a noticeable improvement over the polygon rendering of the Genesis.[3][1][11] The 32X also includes 256 kilobytes of random-access memory (RAM), along with 256 kilobytes of video RAM."
https://en.wikipedia.org/wiki/32X#Techn ... ifications

If someone does crack the 32X then it's a good step towards the Saturn, but I am not holding my breath for either.

It's kind of funny that they talk about polygon rasterization rate, since the 32X's graphics processor doesn't have any hardware polygon rasterization support. It basically just gives you a linear framebuffer to write into, and then lets you combine that with the Megadrive's video output in various ways. The sound capabilities are pretty basic too.

A 32X core could be useful as a testbed for an SH-2 core though. And it would be pretty nice from a preservation perspective, since 32Xs can be a bit finicky, and buying a working unit today can get expensive. It doesn't have the greatest game library though, so the question is whether anyone will consider it worth their time.

If I got it right, one of the biggest obstacles to emulating the Saturn on a PC is the tight synchronization between all the different components in the Saturn. Emulating everything in parallel, on one CPU core (mutli-core generally doesn't help due to latency), results in a huge performance penalty. This is always the case with software emulation, but the Saturn makes the problem a lot worse than other consoles from that era.

Now, implementing the Saturn will not be easy by any means. But having multiple chips (implemented as softcores) run in parallel is one of the strengths of FPGA technology. I can imagine that the gulf in difficulty between the Saturn and the PS1 might get at least a little bit smaller.

With all of that said, I would be surprised if anyone made a Saturn core soon. Most likely we would hear of a simpler system that uses the SH-2 (CPS-3?) long before a Saturn core.

softtest9 wrote: ↑Thu Jun 04, 2020 5:49 pma simpler system that uses the SH-2 (CPS-3?)

The other "major" SH-2 platforms I know of are "Psikyo SH-2" (e.g. Strikers 1945 II/III, Gunbird 2, Tetris: The Absolute: The Grand Master 2, Sol Divide) and Kaneko Super Nova (e.g. Cyvern, Sengeki Striker, Gals Panic 4/S). Several of these games, predictably, have Saturn ports or spinoffs.

We should probably have a subforum for "wishlist cores" so we don't get our hopes up
That said, we will know one is real when the thread explodes...

We should probably have a subforum for "wishlist cores" so we don't get our hopes up
That said, we will know one is real when the thread explodes...

I like that idea : )

Me too, but I know what answer we'll get:
"Instead demanding cores, better create one yourself"

You can always get a Sega Game Gear Micro while waiting for a MISTer Saturn

Interesting tweet...

https://twitter.com/AshEvans81/status/1 ... 2878771207

Says later in the thread that he’s looking at the 32X

Zembar wrote: ↑Sun Jun 07, 2020 7:38 pm Says later in the thread that he’s looking at the 32X

But once 32x is done it will help towards a Saturn core (and other SHX hardware)

I'd like to know more about the board. Is it a consolidated 32x or a modern remake of one of the two boards? Do the chips get sacrificed from aging 32x's and saturns?

It's purly for development purposes and uses off the shelf parts. No consoles were harmed.

Any resulting core wouldn't use it.

meh, back on the old forums, people use to say that SEGA CD, NEO-GEO, GBA and SNES SA-1 probably wouldn't be possible until they actually got released. Where there's a will there's a way I guess. My theory is that we'll get PS1 and N64 first and after that, the top dogs in FGPA development will bang their heads together to produce this final important console core.

I don't think anyone's saying it's impossible, just that it's too big of a project to take for granted that it will happen anytime soon.

ExCyber wrote: ↑Fri Jun 19, 2020 2:36 pm I don't think anyone's saying it's impossible, just that it's too big of a project to take for granted that it will happen anytime soon.

Again, the same things were said about the systems I mentioned. I think the big achievements for the rest of the year will be: 32X, CPS-1, CPS-2, SEGA 16, Atari 7800 and maybe another handheld like NEO-GEO Pocket (OG & Color), Lynx or WonderSwan (OG & Color). In 2021, we will get PS1 or N64.

I think that PS1 will probably come before N64 and maybe before 32X. Highly doubt that 32X will come this year since no developer has said anything about it so far. Another handheld perhaps.

softtest9 wrote: ↑Sat Jun 20, 2020 12:35 pm I think that PS1 will probably come before N64 and maybe before 32X. Highly doubt that 32X will come this year since no developer has said anything about it so far. Another handheld perhaps.

A few cores were surprises last year.

we've seen more lift recently with Saturn considering a development board is being worked on. Sure enough we'll get there, and that day will be total bliss. Imagine if that SH2 tophat was used in combo with FPGA for the rest of the system. I wouldn't be opposed to that. It would be a few steps closer I suppose.

Is the SH-2 the concern? That's already open. https://www.j-core.org/

Is the concern that we'll need a tophat with 2 SH-2's because the FPGA on the DE-10 won't be able to handle the SH-2's and all other processors concurrently?

MadDog wrote: ↑Sun Jul 05, 2020 12:52 am Is the SH-2 the concern? That's already open. https://www.j-core.org/

Is the concern that we'll need a tophat with 2 SH-2's because the FPGA on the DE-10 won't be able to handle the SH-2's and all other processors concurrently?

Interesting read.

https://twitter.com/srg320_/status/1356 ... 71493?s=19

Legit?

I don't see why not srg320 did lots of work on several MiSTer cores.

Holy crap! This is major news. Check out his Twitter feed. He definitely is working on this. He even started a Patreon for those interested in supporting him: https://www.patreon.com/srg320

oh yes, he's doing it, can't believe that <3 ... just became a patreon

I also become patreon.