1.) Wave 1
The HuC6280 (the Hu short for Hudson, also known simply as the C6280) is the main CPU of the TurboGrafx-16. It also handles the graphics and audio of the system. The chip is basically an expanded WDC 65C02 chip. As a result, many third-party developers of the Nintendo Entertainment System (which used the predecessor, the 6502) also developed for the TurboGrafx-16, as the processor chip was similar. However, they still had to account for the hardware differences.
When Hudson and NEC released the SuperGrafx and PC Engine CoreGrafx, they used an updated version called the HuC6280A. However, this updated chip does not change anything about the audio capabilities.
Music and Sound
The HuC6280 was one of the best PSGs of its time; rather than adhere to a set number of waveforms like the Nintendo Entertainment System's 2A03, the HuC6280 features six wavetable synthesis channels, resulting in a similar sound to the Namco WSG. The chip also supports stereo panning, pretty revolutionary for a home console at the time.
The chip is emulated properly by many emulators and players. in_vgm in particular emulates the chip very well.
The HES and VGM formats are compatible with the chip. HES is similar to NSF, in that it contains the audio code of a game. Most, but not all games, have been ripped to HES. VGM is an easier alternative where the music must be manually trimmed and properly looped by hand.