HP vc4725 Troubleshooting Guide: HP Compaq Thin Client vc4725 - Page 5

Power-On Diagnostic Tests The Power-On diagnostics performs basic integrity tests of the hardware to determine its functionality and configuration.If a diagnostic test fails during hardware initialization, the unit simply stops.There are no messages sent to video. The following table lists the tests that are performed on the vc4725 units. Power-On Diagnostic Test Test Boot Block Checksum DRAM Parallel port Serial port Timer RTC CMOS battery NAND Flash device Description Tests boot block code for proper checksum value. Simple write/read pattern test of the first 640k of memory. Initiates the port's driver and determines if the device is present. Tests the serial port using simple port verification test to determine if ports are present. Tests timer interrupt by using polling method. Tests integrity of RTC CMOS battery. Tests for proper NAND flash device ID present.