Reset

The NeoGeo reset "signal path" can be confusing. The involved signals are (MVS only) or  (AES reset button and PST518B),  (main, clean reset signal), and  (phase sync pulse for ).

Path
The reset trigger starts with signals VCCON or RST, which come from either the reset button or the PST518B reset generator. It goes to, which sets its internal watchdog timer to generate a long enough negative pulse on RESET. synchronizes the rising edge to the main clock's falling edge to output a 1mclk negative pulse on RESETP.

VCCON, RST and RESET seem to be open-collector lines. RESET is pulled high by a 4.7k resistor.