Memory mapped registers

Note: Most of the register names here come from neogeo_spex.pdf

System registers, handled by a 74HC259 adressable latch.

Video related registers, probably handled by the LSPC chips.

NeoGeo CD only (from NeoCD's source)
NEO-MGA / LC8953 ?
 * $FF011C (word): read: return 0xff | (region_code << 8);
 * $FF0002 (word)
 * $FF007E,$FF008F (word) dma_mode
 * $FF0105 (byte) upload_type_w
 * $FF0111 (byte) spr_disable
 * $FF0115 (byte) fix_disable
 * $FF0119 (byte) video_enable
 * $FF016F (byte) disable_irq_w
 * $FF0183 (byte) z80_enable