Technical Information

What's Emulated?

• The 65c816 main CPU.
• The Sony SPC700 sound CPU.
• SNES variable length machine cycles.
• 8 channel DMA and H-DMA (raster effects).
• All background modes, 0 to 7.
• Sound DSP, with eight 16-bit, stereo channels, compressed samples, hardware attack-decay-sustain-release volume processing, echo, pitch modulation and digital FIR sound filter.
• 8x8, 16x8 and 16x16 tile sizes, flipped in either direction.
• 32x32, 32x64, 64x32 and 64x64 screen tile sizes.
• H-IRQ, V-IRQ and NMI.
• Mode 7 screen rotation, scaling and screen flipping.
• Vertical offset-per-tile in modes 2, and 4.
• Horizontal offset-per-tile in modes 2, 4 and 6.
• 256x224, 256x239, 512x224, 512x239, 512x448 and 512x478 SNES screen resolutions.
• Sub-screen and fixed color blending effects.
• Mosaic effect.
• Single and dual graphic clip windows, with all four logic combination modes.
• Color blending effects only inside or outside a window.
• 128 8x8, 16x16, 32x32 or 64x64 sprites, flipped in either direction.
• SNES palette changes during frame (15/16-bit internal rendering only).
• Direct color mode - uses tile and palette-group data directly as RGB value.
• Super FX, a 21/10MHz RISC CPU found in the cartridge of several games.
• S-DD1, a data decompression chip used only in Star Ocean and Street Fighter 2 Alpha. The compression algorithm is integrated into Snes9x, but you may still use the old graphics pack cheat as a speed boost.
• SPC7110, similar in use to S-DD1, but the algorithm is still unknown.
• S-RTC, a real-time clock chip. Dai Kaijyu Monogatari II is the only game that uses it.
• SA-1, a faster version of CPU found in the main SNES unit together with some custom game-accelerator hardware.
• C4, a custom Capcom chip used only in Megaman X2 and X3. It's a sprite scaler/ rotator/line drawer/simple maths co-processor chip used to enhance some in-game effects.
• OBC1 is a sprite management chip. Metal combat is the only game to use this.
• Greater DSP-1 support, enough that all games should load, but some may have graphical glitches.
• DSP-2 support. Only used in Dungeon Master.
• DSP-4 support. Used in Top Gear 3000.
• SNES Mouse.
• Super Scope (light gun) emulated using computer mouse.
• Multi Player 5 - allowing up to five people to play games simultaneously on games that support that many players.
• Game Genie and Action Replay cheat codes.
• Multiple ROM image formats, with or without a 512 byte copier header.
• Single or split images, compressed using zip and gzip, and interleaved in one of two ways.
• Auto SRAM (battery backed RAM) loading and saving.
• Freeze-game support, now portable between different Snes9x ports.
• 4-point gaussian interpolated sound.
• Justifier support. Konami's Justifier is similar to the Super Scope and used in Lethal Enforcers.
• Seta-10 CPU (ST010). This is used F1 Race of Champions 2.
• Fixed color and mosaic effects in SNES hi-res. (512x448) modes.
• Offset-per-tile in mode 6.
• Pseudo hi-res.
• Mosaic effect on mode 7.
• Satellaview and BS-X, partially.

What's Not?

• Any other odd chips that manufactures sometimes placed inside the cartridge to enhance games and as a nice side-effect, also act as an anti-piracy measure. (DSP-3, SETA 11 and SETA 18, as examples)
• A couple of SPC700 instructions that I can't work exactly out what they should do.
• The expansion slot found in many carts.

Custom Chips

Super FX

The Super FX is a 10.5/21MHz RISC CPU developed by Argonaut Software used as a game enhancer by several game tiles. Support is still a little buggy but most games work very well, if a little slowly. Released SNES Super FX games included Yoshi's Island (best single-player game on SNES, if you like platform games), Doom, Winter Gold, Dirt Trax FX, StarFox, Stunt Race FX and Vortex.

S-DD1

The S-DD1 is a custom data decompression chip that can decompress data in real-time as the SNES DMA's data from the ROM to RAM. Only two games are known to use the chip: Star Ocean and Street Fighter Alpha 2.

SPC7110

The SPC7110 is a compression and memory mapping chip. It provides a few extra features, as well. It functions as an RTC interface, and has a multiply/divide unit that has more precision than the SNES. The SPC7110 is found only in 4 games: Super Power League 4, Far East of Eden Zero, Far East of Eden Zero - Shounen Jump no Shou, and Momotaro Densetsu Happy.
This chip uses some unknown compression algorithms, so to actually support the games using this, pre-decompressed graphics packs is necessary.

SA-1

The SA-1 is a fast, custom 65c816 8/16-bit processor, the same as inside the SNES itself, but clocked at 10MHz compared to a maximum of 3.58MHz for the CPU inside the SNES.
The SA-1 isn't just a CPU; it also contains some extra circuits developed by Nintendo which includes some very fast RAM, a memory mapper, DMA and, several real-time timers.
Snes9x includes emulation of most features of the SA-1, enough to play all SA-1 games I've located so far, these include Mario RPG, Kirby Superstar and Parodius 3.

C4

The C4 is custom Capcom chip used only in the Megaman X2 and Megaman X3 games. It can scale and rotate images, draw line-vector objects and do some simple maths to rotate them.

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