ADLINK Express-BE - Manual (Page 68)

Page 68 Express-BE
8. BIOS Checkpoints, Beep Codes
This section of this document lists checkpoints and beep codes generated by AMI Aptio BIOS. The checkpoints defined in this document are
inherent to the AMIBIOS generic core, and do not include any chipset or board specific checkpoint definitions.
Checkpoints and Beep Codes Definition
A checkpoint is either a byte or word value output to I/O port 80h. The BIOS outputs checkpoints throughout bootblock and Power-On Self
Test (POST) to indicate the task the system is currently executing. Checkpoints are very useful for debugging problems that occur during the
preboot process.
Beep codes are used by the BIOS to indicate a serious or fatal error. They are used when an error occurs before the system video has been
initialized, and generated by the system board speaker.
Aptio Boot Flow
While performing the functions of the traditional BIOS, Aptio 5.x core follows the firmware model described by the Intel Platform Innovation
Framework for EFI (“the Framework”). The Framework refers the following “boot phases”, which may apply to various status code &
checkpoint descriptions:
• Security (SEC) – initial low-level initialization
• Pre-EFI Initialization (PEI) – memory initialization
1
• Driver Execution Environment (DXE) – main hardware initialization 2
• Boot Device Selection (BDS) – system setup, pre-OS user interface & selecting a bootable device (CD/DVD, HDD, USB, Network,
Shell, …)
Viewing BIOS Checkpoints
Viewing all checkpoints generated by the BIOS requires a checkpoint card, also referred to as a OST Card or POST Diagnostic Card. These
are PCI add-in cards that show the value of I/O port 80h on a LED display.
Some computers display checkpoints in the bottom right corner of the screen during POST. This display method is limited, since it only
displays checkpoints that occur after the video card has been activated.
Keep in mind that not all computers using AMI Aptio BIOS enable this feature. In most cases, a checkpoint card is the best tool for viewing
AMI Aptio BIOS checkpoints.
1 Analogous to “bootblock” functionality of legacy BIOS
2 Analogous to “POST” functionality in legacy BIOS