PRO-CT0

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 and then.

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=

=Internal logic=

Kyuusaku's Verilog definition:

furrtek's version:



=Normal use: graphics multiplexer=

See NEO-ZMC2.

=Derivate use: security device=





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:

Data bus mapping:

Output
Data bus mapping:

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