Ricoh · 1991 · 1990s · 8 voices
The RF5C164 gave the Sega CD eight channels of PCM sample playback from its 512KB audio RAM, enabling the kind of CD-quality instrument samples and digitised audio effects that were impossible on the base Mega Drive hardware.
The Ricoh RF5C164 was an 8-channel PCM sample playback chip that formed the core of the Sega CD's audio subsystem alongside the standard CD audio streaming and the inherited Mega Drive YM2612/SN76489 hardware. Each of the eight channels could play an independently addressed PCM sample at variable pitch and volume with stereo panning, drawing samples from 512KB of dedicated audio RAM. The chip was designed for high-quality sample playback rather than synthesis — it could not generate tones without sample data — making it entirely dependent on the samples loaded into its RAM from the CD. In practice, Sega CD games used it for orchestral instrument samples, vocal snippets, and sound effects that the Mega Drive's FM synthesis could not replicate. Games like Sonic CD exploited the hardware for dynamic CD audio plus PCM sound effects; Shining Force CD and the Working Designs RPG catalogue demonstrated its capacity for near-orchestral game music.