N-SPC Engine/Kemco
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Kemco is the first company outside of Nintendo themselves to release a game using their own variant of N-SPC (that being Bombuzal). The main customization that they did was to have the CPUIO registers play sounds on specific channels, and only the channels on the phase list specified to be used by the corresponding CPUIO register would be used. One other CPUIO register was allocated mainly to perform volume fades.
| Game Name | Version | VCMD Table Location ($E0 and up) | ROM Offset |
|---|---|---|---|
| Bombuzal | 1.0 | 0x10EB, relative to 0x102B | 0x04807A |
| Lagoon | 2.0 | 0x1156, relative to 0x1096 | 0x0D80A4 (all versions) |
| Drakkhen | 3.0 | 0x129E, relative to 0x11DE | 0x1C805C (all versions) |
| Ka-blooey | 3.0 | 0x129E, relative to 0x11DE | 0x048080 |
| First Samurai | 3.1 | 0x129E, relative to 0x11DE | 0x0DB15E (all versions) |
| Phalanx - The Enforce Fighter A-144 | 3.1 | 0x129E, relative to 0x11DE | 0x1EB23E (all versions) |
| Super Drakkhen/Dragon View | 3.1 | 0x129E, relative to 0x11DE | 0x09B6F6 (all versions) |
| Super Full Metal | 3.1 | 0x129E, relative to 0x11DE | 0x0C80B6 |
| X Zone | 3.1 | 0x129E, relative to 0x11DE | 0x0FAEE6 (all versions) |
| Kid Klown in Crazy Chase | 4.0 | 0x12A1, relative to 0x11E1 | 0x1EC1E0 (all versions) |
The raw build sorting notes can be found here.
Communication with the SNES
Each CPUIO register has an individual use.
TODO output for all CPUIO registers on a per-version basis
CPUIO0 ($2140/$F4)
This register always controls which sound ID will play out of channels 1-6, regardless of which sound driver version is used. It also supports the source build's N-SPC/Kankichi commands. TODO
CPUIO1 ($2141/$F5)
This register controls which sound ID will play of of the following channel IDs, depending on the version...
- V1.0, V3.0: Channels 7-8
- V2.0, V4.0: Channel 7
CPUIO2 ($2142/$F6)
Only used in V2.0 and V4.0. This register always controls which sound ID will play out of channel 8.
CPUIO3 ($2143/$F7)
Never used in V2.0.
This CPUIO register is used to perform volume fades. The values supported depend on the sound driver version.
TODO record values here and their purpose on a per-version basis