CXD1800 is a CD interface chip - it was also used in some of Sony's old proprietary interface CD-ROM drives. The NEC chip on the sub board on top is one of their 75 series MCUs, presumably mostly for running the LCD. I guess the QFP with the wire patches next to the CD logic is the mechacon CPU for the CD drive, but the number isn't readable. For comparison, one of the chipsets used in the original PlayStation was CXD2510 (DSP) and CXD1815 (Interface). And the other two chips are simply the SNES sound subsystem - although this is the first time I've ever seen their Sony part numbers.