The CDC9843 is a high-performance clock synthesizer/driver that generates the system clocks necessary to support Pentium®/82430HX/82430VX and PentiumPro 82440FX chipsets. Four host-clock outputs (HCLKn) are programmable to one of three frequencies (50 MHz, 60 MHz, or 66 MHz) via the SEL0 and SEL1 control inputs. Six PCI-clock outputs (PCLKn) are half the frequency of CPU clock outputs and are delayed 1 ns to 4 ns from the rising edge of the CPU clock. In addition, a universal serial bus (USB) clock output at 48 MHz (SBCLK), a floppy controller clock at 24 MHz (FCCLK), and two 14.318-MHz reference clock outputs (REF0, REF1) are provided. All output frequencies are generated from a 14.318-MHz crystal input.
