HP Workstation x2000 hp workstation x2000 - Technical Reference and Troublesho - Page 59

System Board The Input/Output Controller Hub 2 (82801BA) Interrupt Controller The interrupt controller is equivalent in function to the two 82C59 interrupt controllers. The two interrupt controllers are cascaded so that 14 external and 2 internal interrupts are possible. In addition, the ICH2 supports a serial interrupt scheme and also implements the I/O APIC controller. The table on page 74 shows how the master and slave controllers are connected. Timer/Counter Block The timer/counter block contains three counters that are equivalent in function to those found in one 82C54 programmable interval counter/timer. These three counters provide the system timer function and speaker tone. The 14.318MHz oscillator input provides the clock source for these three counters. Advanced Programmable Interrupt Controller You can use the APIC, which is incorporated in the ICH2, in either single-processor or multiprocessor systems, whereas the standard interrupt controller supports only single-processor systems. Real Time Clock The RTC is 146818A-compatible, with 256 bytes of CMOS. The RTC performs two key functions: • Keeps track of the time • Stores system data The RTC operates on a 32.768KHz crystal and a separate 3V lithium battery that provides up to seven years of protection for an unplugged system. The RTC also supports two lockable memory ranges. By setting bits in the configuration space, you can lock two 8-byte ranges to read and write accesses. This procedure prevents unauthorized reading of passwords or other security information. Another feature is a date alarm that allows for a schedule wake-up event as much as 30 days in advance. Chapter 2 59