Power-On Self-Test (Post) - Acer Aspire SA60 Service Manual

Power-On Self-Test (POST)

Before the computer can be used, all the components must be tested and initialized, and the operating system
must be bootstrapped into memory. This process is know as the power-on Self test(POST), generally under
the control of the BIOS.
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. During POST, system
reports test or initialization failure through Beep codes, display error messages on screen(if available), or LED.
The system halts when fatal error occurs.
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
62 Chapter 4