HP Workstation x4000 hp workstation x4000 - Technical Reference manual - Windo - Page 34

System Board System Chipset Clocks Table 2-1 describes the clocks used in the x4000 Workstation. Table 2-1 Clocks Name Description System A CK00-compliant clock synthesizer in a single CKx_SKS clock chip creates the main system clocks using a 14.318 MHz parallel mode crystal reference. Memory Two Direct Rambus Clock Generator (DRCG) chips provide the clocks for the expansion channels to the Memory Expansion Card (MEC). Using the 50 MHz reference clock provided by the system clock generator, each DRCG produces the 400 MHz differential clock needed by the memory expansion channel. The Memory Controller Hub (MCH) provides two pairs of feedback signals to the DRCGs to keep the Host and RDRAM clocks aligned. Real Time Clock (RTC) A 32.768 KHz parallel mode crystal is the reference for the ICH2 real-time clock circuitry. Audio A 24.576 MHz parallel mode crystal is the reference for the Audio Codec. Local Area A 25 MHz parallel mode crystal provides a Network (LAN) frequency reference for the 82550's internal oscillator. SCSI A 40 MHz oscillator provides the SCSI controller SCLK. Zircon A 10 MHz oscillator clocks the Zircon chip. 34 Chapter 2