This is one of a number of (theoretical) conversions using the Namco System 2 hardware platform. The hardware platform consists of a CPU board, video board and occasionally a daughter board attached to an expansion connector on the video board. There appears to be at least three variations of the video board hardware of which I personally have seen two.
The first variation can be identified by the presence of a block of ROZ (rotate & zoom) ROMS and has custom device No. 102 at location 2G. This board was used for most of the none-driving games (like "Assault" & "Cosmo Gang") and I have seen no name on this board.
The second variation does not have ROZ ROMS and has custom device No. 45 at location 2K. This board was used for driving games (like "FourTrax", "Final Lap" and "Final Lap 2") and I've seen at least two board names used for it ("V56 VIDEO" and "SYS2 VIDEO(FL)").
The third variation that I have not seen is used for Metal Hawk (according to MAME 036).
To run "Cosmo Gang" you will need a game that uses the first video board variation. The following games are likely "source" candidates (based on MAME 036) :-
I have tested this conversion on an "Assault" game.
You will need the following items:-
Namco used a key chip to prevent a simple ROM swap. The MAME driver applies patches to the code to defeat the key mechanism so the game can be run under emulation. We can apply these same patches to the ROM images themselves so that the game will run without a key chip on the "real" hardware.
Image CO1MPR0 change location 0x00001A69 from 0x67 to 0x4E
Image CO1MPR1 change location 0x00001A69 from 0x04 to 0x75
Blank all the EPROMS and blow in the images according to the list below:-
CO1CHR0 into 27C040 for location 11N (CHR0)
CO1CHR1 into 27C040 for location 11P (CHR1)
CO1CHR2 into 27C040 for location 11R (CHR2)
CO1CHR3 into 27C040 for location 11S (CHR3)
9N,9P,9R,9S (CHR4,CHR5,CHR6,CHR7) must be unpopulated.
CO1DAT0 into 27C010 for location 13S (DATA0)
CO1DAT1 into 27C010 for location 13P (DATA1)
13R,13N (DATA2,DATA3) must be unpopulated.
CO1MPR0 into 27C010 for location 11D (MPR0)
CO1MPR1 into 27C010 for location 13D (MPR1)
CO1SPR0 into 27C010 for location 11K (SPR0)
CO1SPR1 into 27C010 for location 13K (SPR1)
CO1VOI1 into 27C040 for location 3M (VOICE1)
CO1VOI2 into 27C040 for location 3L (VOICE2)
3N (VOICE0) must be unpopulated.
CO1SHA0 into 27C040 for location 7N (SHAPE)
CO1SND0 into 27C010 for location 7J (SND0)
SYS2C65C into 27C256 for location 3F (C68PRG on some boards)
CO1OBJ0 into 27C040 for location 5B (OBJ0)
CO1OBJ1 into 27C040 for location 4B (OBJ1)
CO1OBJ2 into 27C040 for location 5D (OBJ2)
CO1OBJ3 into 27C040 for location 4D (OBJ3)
5C,4C,5F,4F (OBJ4,OBJ5,OBJ6,OBJ7) must be unpopulated.
J203 must be unconnected (i.e. any daughter card should be removed).
CO1ROZ0 into 27C040 for location 1A (ROZ0)
1B,1C,1D,3A,3B,3C,3D (ROZ1,ROZ2,ROZ3,ROZ4,ROZ5,ROZ6,ROZ7) must be unpopulated.
There are few jumpers that need to be changed to reflect this memory configuration:-
JP60 (near 8P pin 64) 2-3 ( *[O--] )
JP66 (near 8P pin 64) 1-2 ( *[--O] )
JP68 (near 8P pin 64) 1-2 ( *[--O] )
JP67 (near 7N pin 32) 1-2 ( *[--O] )
JP88 (next to 9S pin 32) 1-2 ( *[--O] )
JP86 (next to 9S pin 28) 1-2 ( *[--O] )
JP80 (next to 9S pin 25) 2-3 ( *[O--] )
JP87 (next to 9S pin 19) 1-2 ( *[--O] )
JP15 (next to 13S pin 32) 1-2 ( *[--O] )
JP3 (next to 4L pin 4) 1-2 ( *[--O] )
JP4 (next to 4L pin 4) 2-3 ( *[O--] )
JP1 (near 5L pin 1) 2-3 ( *[O--] )
JP2 (opposite 5L pin 6) 1-2 ( *[--O] )
JP8 (next to 1D pin 19) 1-2 ( *[--O] )
JP7 (next to 1D pin 19) 2-3 ( *[O--] )
JP6 (near 3D pin 32) 2-3 ( *[O--] )
JP5 (near 3D pin 32) 2-3 ( *[O--] )
Remove the device at location 5G (CUSXX) if present. Attach the diode between pin 13 and pin 26 on the reverse side of the board such that the stripe-end of the diode is attached to pin 26.