Clock
In cartridge systems
The main system clock (sometimes called mclk) is 24MHz. It is generated and divided by 2, 4 and 24 by NEO-D0 to provide the 12MHz clock for NEO-ZMC2, the inverted 6MHz one for video output and also the 1MHz one for NEO-B1.
As LSPC2-A2 is clocked on both edges of the 24MHz clock, it is able to divide it by 3 and 6 to provide the 8MHz clock for the YM2610 and the 4MHz one for the Z80.
The cartridge connector provides the 24M, 12MHz, 8MHz and 4MHz inverted clock signals.
A second quartz is used for generating the color burst needed by composite video, for the video encoders.
"B" signals are phase-inverted.
In CD systems
NEO-GRC ?