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Mvs pro-ct0.jpg
Package SDIP64
Manufacturer Logo nec.jpg
First use 1990 ?
Approx. gates ?
Used on Pcb.pngMV4 Cartridges...

PRO-CT0 is an early gate array chip used as:

  • A sprite graphics multiplexer on AES carts and MVS boards, sometimes named ALPHA-8921, later replaced by Chipicon.png NEO-ZMC2 and then Chipicon.png NEO-CMC.
  • Security device in Super Sidekicks and Fatal Fury 2 AES and MVS cartridges, also named SNK-9201.

The device probably wasn't intended to be used as as security measure at first.

ALPHA-8921 was the original chip name, from when Alpha Denshi used it on their Alpha68k system.


Sprite graphics mux Security device
Pro-ct0 pinout.png Snk-9201 pinout.png
Info by User:Kyuusaku
  • D0~D15: 68k data bus
  • A1~A19: 68k address bus
  • D0out~D7out: output to a LS245 which puts the data on

the 68k bus when /PORTOEL goes low ($200000-$2FFFFF odd byte read).

Internal logic

Kyuusaku's Verilog definition:

furrtek's version:

Proct0 ftk.png

Use as graphics multiplexer


Use as security device

PRO-CT0 9042KX023 on an AES cart PROG board as a security chip
SNK-9201 chip found in a Super Sidekicks MVS cartridge. Picture courtesy of [MVS-Scans].

Used on PROG-G2 boards. It is found in Fatal Fury 2 and Super Sidekicks only. It was SNK's first attempt at protecting NeoGeo games.

The chip is tied to the 68k address and data bus, listens to word writes and replies on odd addresses in the $200000-$2FFFFF address range.

The game program expects the chip to reply with specific data depending on the values written to it and will freeze if they are wrong.

Address bus mapping:

A19 A18 A17 A16 A15 A14 A13 A12 A11 A10 A9 A8 A7 A6 A5 A4 A3 A2 /PORTWEL A1
C31 C29 C27 C25 C30 C28 C26 C24 C23 C21 C19 C17 C22 C20 C18 C16 H EVEN 12M LOAD

Data bus mapping:

D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
C15 C13 C11 C9 C14 C12 C10 C8 C7 C5 C3 C1 C6 C4 C2 C0

For specific details see Fatal Fury 2 and Super Sidekicks.


MAME: prot_fatfury2.cpp