Author Topic: Is it physically impossible to emulate the Super Gameboy on the SD2SNES?  (Read 13540 times)

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Offline bluefoxicy

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Quote from: ikari_01
OTOH Super Gameboy might not be too far out of reach
as it already works in "real life" through the cartridge bus.
There is hope  ::) ::)

Considering the DSP-1 is a 10MHz 65c816 (yes, it's more powerful than the SNES main core itself) and the Gameboy Color is an 8.38MHz Z80, it's logically doable.  Mind you, the SD2SNES Pro is a Cyclone IV now; it's actually powerful enough to implement a hardware SNES.

Best approach would be to load the sprites destined for the Gameboy Color PPU into the SNES PPU, essentially hardware virtualizing the PPU rather than reimplementing and shuffling video.  You can do the same with the NES and Genesis if you really have that kind of programmer time; Gameboy Advance displays too many colors.

Offline the_randomizer

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Why not the Super Game Boy 2? It's much better and actually has the proper timing, audio doesn't sound weird.

Offline nuu

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I think the Super Game Boy is discussed in a general sense. If the SGB can be done, there is not much left to do for it to become an SGB2. Mainly the link port.

Offline Galron

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Also the whole timing issue can be fixed on a gbav1.

Offline nuu

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Yes by adding a clock crystal that matches the Game Boy's. A link port can also be added.

Offline D2DEZEL

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Offline Gumball

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http://helmet.kafuka.org/bboard/thread.php?id=178
I checked the link. What exactly does this mean? I only saw stuff related to BSNES. Does super gameboy work on the sd2snes now? or what.
All I wanna do is shred.

Offline Relikk

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http://helmet.kafuka.org/bboard/thread.php?id=178
I checked the link. What exactly does this mean? I only saw stuff related to BSNES. Does super gameboy work on the sd2snes now? or what.

MSU1 type capability for Game Boy games.

Offline bluefoxicy

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Yes by adding a clock crystal that matches the Game Boy's. A link port can also be added.

Cyclone IV handbook says the EP4CE15E17C8N has 15,048 LEs, 594 Kbit embedded memory, 66 18x18 embedded multipliers, 4 general-purpose PLLs, 20 global clock networks, 8 user I/O banks, and 343 maximum user I/Os in the EP4CE15 series but 256 pins on this version.  As a 1.2V version (not low-power), it has a top clock speed of 166MHz; timing issues will apply, but the Gameboy is 4.194304MHz, and the GBC 8.388608MHz (twice GB).

The FPGA allows M, N, and C counters from 1 to 512.  The PLL multiplies the clock by M/(N*post-scale counter).  I see an A510N, which is a 32.768MHz oscillator.  For GBC, you'd need to multiply by 1/0.256, or 1000/256, so use 125/32.  For Gameboy, use 125/64.  Divide these by 2 for the PPU clock and 4 for the CPU clock (if you need PLLs, just produce the PPU clock in the first place, and divide it by 2 for the CPU clock).  Gameboy Advance clock is twice the GBC clock, but it uses a superscalar ARM processor and implementing that is difficult (and might cause timing issues, requiring slower clock speeds, although the FPGA can probably handle it), plus the FPGA may not have enough LEs.

SD2SNES also has a USB port, so you just need a USB-to-link-cable.

SD2SNES is open-source, so maybe start a kickstarter to pay someone to implement all this stuff.  Should work on SD2SNES Pro but it's going to be as much of a lift as creating an FPGA Gameboy Color.

Offline D2DEZEL

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Offline Erockbrox

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I would love to see the SD2SNES Pro be able to have "cores" like the Mister project where you can play Atari 2600, NES, Genesis and such all with just the SD2SNES Pro.

Offline nuu

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You mean something like the Super Game Boy but for other systems? It can't probably be more powerful than a Game Boy though, the SNES needs to be able to handle outputting the video.

Offline Galron

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Offline ikari_01

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That is very easy to do on NES (within its palette/resolution capabilities of course) but impossible on SNES.
On NES the graphics chip is connected directly to the cartridge slot, on SNES everything has to be copied from cartridge to the graphics chip using the CPU / DMA.
To make matters worse you can only transfer to the graphics chip when it's not drawing anything on screen, so it's just waiting 85% of the time (on NTSC).

Regarding cores, actually it's already loading individual cores for their respective special chip support ;) Note that the FXPAK Pro FPGA is only around 10% the size of MiSTer so it wouldn't get you very far anyway ;)

Offline Richardragon87

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That is very easy to do on NES (within its palette/resolution capabilities of course) but impossible on SNES.
On NES the graphics chip is connected directly to the cartridge slot, on SNES everything has to be copied from cartridge to the graphics chip using the CPU / DMA.
To make matters worse you can only transfer to the graphics chip when it's not drawing anything on screen, so it's just waiting 85% of the time (on NTSC).

Well if anything made by Anthrox (Which I must add were made Wayyyy back in 1996) was proof enough it goes without saying NES games could have worked on a SNES... just look up the game "BurgerTime (A&S NES Hack)" for example and try it. Am not sure if it exists on later packs but as I run an older one it clearly exists in the Hacks folder of the Super Famicom/Super Nintendo pack dated back in the 2010's but it should exist in later sets too.

There was also games like Star Soldier and a few others too if I recall
« Last Edit: January 30, 2020, 10:22 PM by Richardragon87 »
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