Chapter 5 
Operation 
5.1POST
After power up or reset, the BIOS performs a self-test, POST, that attempts to determine if further operation is possible and that the detected configuration is expected. This process either completes normally or results in a warning or an error. The boot process does not stop after a warning but displays a message on the primary display device.
To view all checkpoints generated by Aptio firmware, you require a checkpoint card, also referred to as a POST Card or POST Diagnostic Card. These are LPC add-in cards that show the value of I/O port 80h on a LED display.
5.2Boot Process
While performing the functions of the traditional BIOS, Aptio 4.x core follows the firmware model described by the Intel Platform Innovation Framework for EFI. The framework refers to the following boot phases, which applies to various status code descriptions:
zSecurity (SEC) - initial low-level initialization
zPre-EFI Initialization (PEI) - memory initialization1
zDriver Execution Environment (DXE) - main hardware initialization2
zBoot Device Selection (BDS) - system setup, pre-OS user interface and selecting a bootable device (CD/DVD, HDD, USB, Network, Shell, and so on)
5.3Initiating Setup
During the boot, press the F2 key on the keyboard to launch the setup utility once the self-test is complete and before searching for a boot device. If you exit setup without saving any changes, the boot process continues with the search for a boot device. If changes are made, the motherboard loads the new settings and resets, restarting the entire boot process.
