Nintendo S-SMP

The Sony SPC700 is an 8 -bit sound chip, which was designed by Ken Kutaragi and together with a Digital Signal Processor (DSP ) in the Super Nintendo Entertainment System ( SNES) game console using found. The SPC700 together with the associated 16- bit DSP is designed and manufactured by Sony. Later, Sony entered the game console market with the PlayStation. For its time (1990 ) the SPC700 chip was very progressive and can be limited even compared to today's wavetable synthesizer sound cards.

Technology

In the SNES SPC700 above the DSP is attached. The sound chip internally contains 64 KB of RAM and runs at a clock frequency of 2.048 MHz. He has six internal registers and can execute 256 opcodes. SPC700 sound samples are stored in RAM in a compressed format that is similar to ADPCM. The command set is similar to the 6502 CPU series, but includes additional commands, such as XCN (Exchange nibble), which swaps the upper and lower 4 - bits of the output signal of the 8- bit register, and a command of an 8-bit x 8-bit multiplication and storage in a 16 -bit register enables.

The SPC700 belonging to the DSP works similar to modern wavetable sound cards such as the Sound Blaster Audigy. It can eight votes will be simultaneously produced in any suitable pitch and volume. It also supports voice panning, ADSR, Echo with filtering ( via a programmable 8 -tap FIR (Finite Impulse Response) ), and the use of noise as a sound source ( useful for certain sound effects such as wind). The output signal is a 16-bit stereo generated with a sampling rate of 32 kHz. The communication of the SPC700 with the DSP is done via memory mapped I / O.

The SPC700 has a rather unusual way of working for a sound chip. The main CPU of the SNES transmits commands and data blocks to the internal memory of the sound samples SPC700. These commands consist of machine code and developed for the SPC700 in almost the same way as for PCs or Macs. As such may be considered as the SPC700 coprocessor for the sound of the SNES. This is an advantage compared to the Game Boy Advance, in which the ARM7 CPU has to do all the sound engine.

The emulation -based sound format " SPC" is derived from the name of this sound chips.