Before revision: It used a 1.193182 MHz clock signal (one third of the color burst frequency used by NTSC, one twelfth of the system clock crystal oscillator ) and contains three timers.
After revision: , therefore one quarter of the 4.77 MHz CPU clockIt used a 1.193182 MHz clock signal (one third of the color burst frequency used by NTSC, one twelfth of the system clock crystal oscillator ) and contains three timers.