Acer Veriton 3200 Veriton 3200 Service Guide - Page 68

Power-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 the user. 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 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. The main components on the main board that must be diagnosed and/or initialized by POST to ensure system functionality are as follows: ! Microprocessor with built-in numeric co-processor and cache memory subsystem ! Direct Memory Access (DMA) controller ! Interrupt system ! Three programmable timers ! ROM subsystem ! RAM subsystem ! RTC RAM subsystem and real time clock/calendar with battery backup ! Onboard serial interface controller ! Onboard parallel interface controller ! Embedded hard disk interface and one diskette drive interface ! Keyboard and auxiliary device controllers ! I/O ports ! PS/2-compatible mouse port ! PS/2-compatible keyboard port ! Serial ports ! Parallel ports ! USB port 61 Chapter 4