Acer Veriton FP2, Service Manual

Page: 74 / 124

68 Chapter 4
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
!
Serial port
!
Parallel port
!
USB ports