## 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?

- DSP-1 support not complete, enough to play Mario Kart, Pilotwings and many others. All DSP-1 games should boot, but may display graphical errors.
- 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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