NEO-CMC
The most "basic" information published can be found at [MAME:neocrypt.c]
The detailed information bellow:
The NEO-CMC Chip is a Asic (Application Specific Integrated Circuit). This device can be programmed only once after the manufaturer had created severals stable prototypes using FPGA (Field Programmable Gate Array) or another technology. And decide to create a Custom Chip
To get a intuition about costs related read this: [FPGA vs ASICs production and design]
So SNK had planned to put his next protection and try to avoid NeoGeo piracy using the NEOCMC algorithm.
The Toshiba as partner of SNK, not only made solution to hold data on it's Mask Roms (TC5xxxx) as used its technology solutions to help SNK try to avoid the Piracy. Toshiba until 1995 had a line of Asics called TC190G series, the evolution can be found here [Toshiba Technology RoadMap].
One of the series of its technology that was best switable to SNK was TC190G series of ASIC.
The series TC190G cannot be found in datasheets anymore, but in past years had these models of chips:
- TC190G06CF7008
- TC190G06CF7042
- TC190G06CF7050
may be more...
Apparently the last two models was used because the number of internal gates was compatible what SNK wanted, to build inside this custom the following logic algorithms:
- NEO-ZMC
- NEO-273
- And a new scrambling system for that interlaces M1 + CX + S1 ROM data
Than, released model of CMC was NEO-CMC42 in 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 was in normal condition (unencrypted)
This was just a just a test to see if SNK and Toshiba could be more further in protection
Next SNK just incremented a new scramble and some tests point into M1 to validate the sync decryption and this caused to SNK release 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 |
About Jockey Gran Prix, some peoples say this game is not official release but it´s not true. At least its production of the card is official, because they had used the REAL Encryption that cannot be mocked easly. Only the Toshiba and SNK knew the encryption and until today "NO ONE" piracy goes so forensic to mock it. Explanation Later.
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.