
Package	SDIP64
Manufacturer
First use	1990 ?
Used on	MV4 Cartridges...

PRO-CT0 (also known as SNK-9201 and ALPHA-8921) is an early gate array chip which serializes sprite graphics in AES cartridges and MVS boards. It was later replaced by NEO-ZMC2 and then NEO-CMC.

It was also used as a challenge-response "security" device in Super Sidekicks and Fatal Fury 2 cartridges.

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

Pinouts

Sprite graphics mux

Security device

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: File:Ct0.zip

furrtek's version:

Normal use: graphics multiplexer

See NEO-ZMC2.

Derivate use: security device

PRO-CT0 9042KX023 on an AES cart PROG board.

File:Crt snk-9201.jpg

SNK-9201 chip found in a Super Sidekicks MVS cartridge. Picture courtesy of [MVS-Scans].

As a security device, the chip is only found on PROG-G2 boards for Fatal Fury 2 and Super Sidekicks. It was SNK's first attempt at copy-protecting NeoGeo games.

The chip is tied to the 68k address and data bus, it reacts 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. If the values don't match, then the game assumes it's a copy and silently sets a flag which triggers deliberate bugs during gameplay (see game pages for details).

Input

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

Output

Data bus mapping:

D7	D6	D5	D4	D3	D2	D1	D0
GBD1	GBD0	GBD3	GBD2	GAD1	GAD0	GAD3	GAD2

Emulation

MAME simply uses a list of hardcoded values since the games always use the same challenges. See /src/devices/bus/neogeo/prot_fatfury2.cpp

PRO-CT0

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