kuk (./25) :
it's hard to explain, it's on the sprite rendering/aspect
like if all the pixel are not "present" like a probleme with the scan line

Consider that in this case we don't have all MAME complex routine but only a "simple" emulation.

This is a very complex project in the end because I need a new Z80 emu core in 68K Assembler core and I can't be able to do this (maybe someone can help me).
12Mhz for the NeoGeo 68K CPU is a very little speed for arcade emulation, but if someone did code a Z80 core that could run at a few MHz on the Neo Geo, it would open the door for a *lot* of new arcade games for NeoGeo system!

This is only a first step...