Most infos from [MAME:neocrypt.c]

C and (merged) S ROM banking and decryption chips found on CHA cartridge boards, in two (?) versions:

"CMC50"

Also found on ROM-only arcade boards, without the "NEO-CMC" marking.

Pinout

Notes:

C_e_D[0-15]: C1/C3/C5/C7 data bus
C_o_D[0-15]: C2/C4/C6/C8 data bus
CX A[0-21]: C1/C2/C3/C4/C5/C6/C7/C8 address bus
Pins 87,88 contains a RC circuit clock driver like in a 8085 with X1 and X2 pinouts
Pins 89 and 92 are short circuited in Cartridge board.

NEO-CMC