The system bus operates at a clock frequency that is 3 to 15 times lower than the internal clock frequency , or 20 to 100 MHz with an internal clock frequency 300 MHz .
The external interface is a 128 - bit system bus .
The system bus   operates at a clock frequency that is 3 to 15 times lower than the internal clock frequency , or 20 to 100 MHz with an internal clock frequency 300 MHz .
The external interface is a 128 - bit system bus .