The ICS9150-01 generates all clocks required for high speed RISC or CISC microprocessor systems such as Intel PentiumPro. Two different reference frequency multiplying factors are externally selectable with smooth frequency transitions. An output enable is provided for testability. High drive PCICLK and SDRAM outputs typically provide greater than 1 V/ns slew rate into 30 pF loads. CPUCLK outputs typically provide better than 1V/ns slew rate into 20 pF loads while maintaining 50 5% duty cycle. The REF clock outputs typically provide better than 0.5V/ns slew rates.