Acer Veriton 3000 Veriton 3000 Service Guide - Page 98

Power-on Self-Test (POST) The power-on self-test (POST) is a BIOS procedure that boots the system, initializes and diagnoses the system components, and controls the operation of the power-on password option. If the POST discovers errors in system operations at power-on, it displays error messages on-screen, generates a check point code at port 80h, or even halts the system if the error is fatal. What does the POST check for you ? The main components on the main board that are diagnosed and/or initialized by the POST to ensure system functionality are as follows: T Microprocessor with built-in numeric co-processor and cache memory subsystem T Direct Memory Access (DMA) controller (8237 module) T Interrupt system (8259 module) T Three programmable timers (system timer and 8254 module) T ROM subsystem T RAM subsystem T RTC RAM subsystem and real time clock/calendar with battery backup T Onboard serial interface controller T Onboard parallel interface controller T Embedded hard disk interface and one diskette drive interface T Keyboard and auxiliary device controllers T I/O ports T PS/2-compatible mouse port T PS/2-compatible keyboard port T Serial ports T Parallel ports T USB port 66 Chapter 4