Video DAC



The NeoGeo uses a discrete video Digital-to-Analog Converter made of resistors fed by two 74LS273 latches which store the color value from the palette RAM and 74LS06 inverters. This is controlled by either, or.





Each color component has its own set of 7 resistors. 6 of them are used for the actual color value (5 + 1 common bit). The last (SHADOW signal) is related to the and  registers (system latch).

Arcade
The output goes straight to the JAMMA connector as a 0~3.5V signal for high-impedance inputs (arcade monitors).

Home
The output is divided by 2200 / (6800 + 2200) = 4.1 to obtain a ~0.9Vp-p max signal, which feeds the video encoder for amplification and conversion to composite.