NEO-CMC



Late SNK custom chip used for protection, bankswitching and latching on CHAFIO CHA boards.

Descrambling/decryption infos can be found in [MAME:prot_cmc.c]

Versions
This chip is a TC190G series Toshiba ASIC developed between 1990 and 1994.

The datasheet apparently can't be found anymore for any of the known types: (probably others...)
 * TC190G06CF7008
 * TC190G06CF7042
 * TC190G06CF7050

SNK merged the following designs into this chip:
 * New scrambling system that interlaces M1 + (C* + S1) to decrypt all the graphics ROMs data in real time.
 * New scrambling system that interlaces M1 + (C* + S1) to decrypt all the graphics ROMs data in real time.
 * New scrambling system that interlaces M1 + (C* + S1) to decrypt all the graphics ROMs data in real time.

The first released NEO-MVS CHAFIO PCBs came out with the 042 version of NEO-CMC, on the following cartridges:
 * Zupapa!
 * The King of Fighters '99 - Millennium Battle
 * Ganryu
 * Garou - Mark of the Wolves
 * Strikers 1945 Plus
 * Prehistoric Isle 2
 * Metal Slug 3
 * Bang Bead
 * Nightmare in the Dark
 * Sengoku 3

On this version only the S1 and C ROMs are encrypted and M1 remains unencrypted. Almost one year later, SNK decided to add one more layer, this time also encrypting M1. This new NEO-CMC chip had the 050 reference and was found in the following cartridges:
 * Jockey Grand Prix
 * The King of Fighters 2000
 * The King of Fighters 2001
 * Metal Slug 4
 * Rage of the Dragons
 * The King of Fighters 2002
 * Matrimelee
 * Pochi and Nyaa
 * Metal Slug 5
 * SNK vs. Capcom - SVC Chaos
 * Samurai Shodown V
 * The King of Fighters 2003
 * Samurai Shodown V Special

Until today, nobody has released a cloned chip on the underground market.

Fix handling
See fix bankswitching.

Encryption
Todo.

=Pinout=

OpenOffice Draw file:

Signals:
 * C_e_D[0..15]: C odd data bus
 * C_o_D[0..15]: C even data bus
 * CX A[0..21]: C1~8 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 shorted.