I've always found Nintendo's audio architectures to be fascinating.
The original NES had a sample generator that could do arbitrary waveforms and could be driven in two modes: one mode is you gave it a memory address and it'd start reading the bits in and treat them as an incredibly simple waveform (1 means 'go up one value', 0 means 'go down one value'... So to do a flat wave you'd do a run of 10101010etc.).
But you could also direct-drive the chip by continuously feeding it an "initial value" directly from the CPU, which was actually faster than the audio driver would read the bits from RAM itself... Problem is that doing so ate up all your CPU cycles, so you could only do it if you weren't doing anything else.
There were some games that took advantage of that: Battletoads had higher-fidelity drum-hits that they could play when action was paused, and they used it for the title screen, the extra-"crunchy" final hits on enemies (where all the action paused for a moment for dramatic effect), and the memorable pause music.
Here's a demo of the game switching between direct-drive and let-chip-read-samples mode to demonstrate (credit to Retro Game Audio for uploading the emulator-doctored video to show when the game is in the direct-drive subroutine). https://www.youtube.com/watch?v=JGT0FM3yh-w
The original NES had a sample generator that could do arbitrary waveforms and could be driven in two modes: one mode is you gave it a memory address and it'd start reading the bits in and treat them as an incredibly simple waveform (1 means 'go up one value', 0 means 'go down one value'... So to do a flat wave you'd do a run of 10101010etc.).
But you could also direct-drive the chip by continuously feeding it an "initial value" directly from the CPU, which was actually faster than the audio driver would read the bits from RAM itself... Problem is that doing so ate up all your CPU cycles, so you could only do it if you weren't doing anything else.
There were some games that took advantage of that: Battletoads had higher-fidelity drum-hits that they could play when action was paused, and they used it for the title screen, the extra-"crunchy" final hits on enemies (where all the action paused for a moment for dramatic effect), and the memorable pause music.
Here's a demo of the game switching between direct-drive and let-chip-read-samples mode to demonstrate (credit to Retro Game Audio for uploading the emulator-doctored video to show when the game is in the direct-drive subroutine). https://www.youtube.com/watch?v=JGT0FM3yh-w