XQ333A0 is the sample ROM (2Mbytes) and the NEC chip is sample RAM (128KBytes) used for custom samples that you can toy around with bundled software. YMF290 is a chip that captures MIDI data and generates an interrupt that the TSR will then use to read back that data from the chip and emulate things through YMF278, it is a clever solution and will work with pmode and through Windows also. YSS205 is a poorman's effects processor + DAC for the YMF278 and the LHxxxx is PSRAM that holds the effect data. AD1848 is the DAC+ADC+mixer, WSS type stuff. OPTi translates SB data to WSS data in SB mode and provides CD interface and means to access the effects chip. AD1848 output is routed through the effects chip and get the currently loaded effect applied on top.
The software that sets up the effects chip doesn't do any sort of delays between the writes and it causes the process to fail on hardware much faster than P1 @ 133MHz unless you add a lot of wait states on ISA accesses or disable caches. One day I will hack the software to allow things to work with faster hardware. You will get strage noises or no sound at all on faster hardware as the effect coeffs are all mangled up as they get written to the chip.