NEO-CMC

"CMC42" chip on a MVS cartridge. Picture courtesy of [MVS-Scans].

The most "basic" information published can be found at [MAME:neocrypt.c]

Bellow the detailed information:

The NEO-CMC Chip is a Asic (Application Specific Integrated Circuit). This device can be programmed only once after be created severals prototypes until reach the stable condiction, using FPGA (Field Programmable Gate Array). The Asci must be considerated a final step from this process.

To get a intuition about costs related, please read this: [FPGA vs ASICs production and design]

SNK had planned to put his next protection to try avoid NeoGeo piracy using the NEOCMC algorithm and the new PCB NEO-MVS CHAFIO.

Because Toshiba was partner and not only made solution to hold data on it's Mask Roms (TC5xxxx), they has used its technology in Asic solutions to help to create this Chip. Until 1995 Toshiba had a line of Asics called TC190G series, the evolution of this series can be found at [Toshiba Technology RoadMap].

The serie that SNK get advantage to build a valuable chip with it's algorithm to protect Cs and S1 initially was the serie TC190G:

The series TC190G cannot be found in datasheets anymore, but in past years had these models:

• TC190G06CF7008
• TC190G06CF7042
• TC190G06CF7050

and more...

Apparently the last two models was used because the number of internal number of gates acceptable to the logic SNK have developed:

• NEO-ZMC
• NEO-273
• And a new scrambling system that interlaces M1 + (CX + S1) ROM data

Inicially the released model of CMC was NEO-CMC42 on the following cartridges:

CART ID	TITLE NAME
070	Zupapa
251	King Of Fighters 99
252	Ganryu
253	Garou Mark Of the Wolves
254	Strikers 1945
255	Prehistoric Isle 2
256	Metal Slug 3
259	Bang Bead
260	Nightmare in the Dark
261	Sengoku 3

This version had only S1 and CRoms Encrypted and M1 remained in normal condition (unencrypted). This was just a "test", to see if SNK and Toshiba could be more further in protection. Almost one year later SNK decided release one more layer on the algorithm, to encrypt M1 on the mixer.

So they released the model NEO-CMC50 on the following cartridges:

CART ID	TITLE NAME
008	Jockey Grand Prix
257	King Of Figthers 2000
262	King Of Figthers 2001
263	Metal Slug 4
264	Rage of the Dragons
265	King Of Fighters 2002
266	Power Instinct - Matrimele
267	Pochi to Nyaa
268	Metal Slug 5
269	SNK vs Capcom Chaos
270	Samurai Showdown Zero / Samurai Showdown 5
271	King of Fighters 2003
272	Samurai Showdown Zero Special / Samurai Showdown 5 Special

Some peoples talk about Jockey Grand Prix not be a official game, but it´s not true. At least it's production was official of the card was official, because they had used the real encryption that cannot be mocked easily. Only the Toshiba and SNK knew the encryption. And until today "NO ONE" piracy goes so forensic to mock it. They prefer just Dump and use the dumped version on its own solution rater use the same chips. That explain why several M1 Rom release over the web wasn't correct until Andreas Naive create a mathematical algorithm and publish. This made capable to create a correct DUMPED version of the M1, but the actual released algorithm will not help anybody that desire to put other unencrypted game in the encrypted condition over NEO-MVS CHANFIO PCB. This will not work!!! Explanation Later.

File:Brd cmcnoref.jpg

"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.