S-SMP

The S-SMP is a Sony SPC700 series 8-bit 65x-based MPU which serves as the SNES' sound chip. It talks to the Ricoh 5A22 over four ports via the SNES Bus. It is clocked by CPUK.

The following registers are 8-bit:

• Accumulator
• X Index Register
• Y Index Register
• Program Status Word
• Stack Pointer

The following registers are 16-bit:

• Program Counter
• YA

Instructions that try to access memory straddling past the end of ARAM (the last byte of which is at $FFFF) will wrap around and end up accessing the zeropage (which is at $0000). Accesses that use direct page addressing will wrap within the direct page.

The stack is always located in page one (at $0100). Memory accesses that straddle the end of the stack will wrap to the beginning of the stack.

Operands that use absolute addressing are prefixed with an exclamation point (!).

See Also

• SPC700 Opcode Matrix

Reference

1. anomie's SPC700 doc
2. page 3-1-1 of Book I of the official Super Nintendo development manual