A DSP chip from Capcom; it is actually a Hitachi HG51B169 as confirmed by decapping. There are 1024K words of 24-bit instructions, running as 20.000MHz. and it is used in 2 games:
Cx4 Command Matrix
Cx4 Opcode Matrix
SNES Expansion Chips
Megaman X3 / Rockman X3
SFROM File Format
Once you've programmed a game or other bit of data for SNES, you'll probably want to try to, well, test it.
Although for most software these choices are, mostly, about preference. Most games which require Expansion Chips other than the DSP-1 may require less than favorable methods of testing (either emulation or reproduction cartridge).
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