Chapter 4Chapter 4 67TroubleshootingThis chapter provides troubleshooting information for the Aspire 7100.q Power-On Self-Test (POST)q Index of Error Messagesq Index of Error Symptomsq Undetermined ProblemsPower-On Self-Test (POST)Each time you turn on the system, the power-on self test (POST) is initiated.Several items are tested during POST, but is for the most part transparent to theuser.The Power-On Self Test (POST) is a BIOS procedure that boots the system,initializes and diagnoses the system components, and controls the operation ofthe power-on password option. If POST discovers errors in system operationsat power-on, it displays error messages on screen, generates a check pointcode at port 80h or even halts the system if the error is fatal.The main components on the system board that must be diagnosed and/orinitialized by POST to ensure system functionality are as follows:q Microprocessor with built-in numeric coprocessor and cache memorysubsystemq Direct memory access (DMA) controller (8237 module)q Interrupt system (8259 module)q Three programmable timers (system timer and 8254 module)q ROM subsystemq RAM subsystemq RTC RAM subsystem and real time clock/calendar with battery backupq Onboard serial interface controllerq Onboard parallel interface controllerq Embedded hard disk interface and one diskette drive interfaceq Keyboard and auxiliary device controllersq I/O portsq PS/2-compatible mouse portq PS/2-compatible keyboard port
