Here are some pictures about a disassembled Marty. Unfortunately the pictures are not big enough to take a closer look, especially for the chips .
Indeed, so what we can scavenge from the pictures and the posts there:
http://nfggames.com/forum2/index.php?topic=2130.0and there:
http://assemblergames.com/forums/archive/index.php/t-12771.htmlp/t-14904.htmland another place I cannot link to...
Is:
FM Towns Marty
CPU: AMD DS39473A
OSC2: 32 MHz (1/2 divider makes the CPU 16 MHz)
OSC1: 28.63636
Video: CE31755, custom, 160-pin
Video DAC: MB40968V
Sound: Yamaha YM3xxx (likely YM3438 OPN2C - and Barry already has Ricoh RF5c68 in the driver)
VRAM: 512kB in four 128kB TMS48C121DZ chips
Sprite RAM: 128kB Sprite RAM in one TC511664BJ-80 chip
ROM: 2x Hitachi HN624116 (256KB each) and 6x or 7x 512KB unknown
and FM Towns Marty 2 has those same specs.