Timing

The (NTSC) PC Engine is clocked with a master clock equal to six times the NTSC color burst ( MHz), or approximately 21.47727 MHz.

This is divided into the following clocks:


 * CPU "high" clock speed = master clock / 3 (approx. 7.15909 MHz),
 * CPU "low" clock speed = master clock / 12 (approx. 1.78978 MHz),
 * Timer speed = master clock / 3072 (approx. 6.991 KHz),
 * VCE pixel clocks:
 * "10MHz" = master clock / 2,
 * "7MHz" = master clock / 3,
 * "5MHz" = master clock / 4.