Checkpoints

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. Checkpoint sare very useful in aiding software developers or technicians in debugging problems that occur during the pre- boot process.

Viewing BIOS checkpoints

Viewing all checkpoints generated by the BIOS requires acheckpoint card, also referred to as a POST card or POST diagnostic card. These are ISA or PCI add-in cards that show the value of I/O port 80h on a LED display. Checkpoints may appear on the bottom right corner of the screen during POST. This display method islimited, since it only displays checkpoints thatoccur after the video card has been activated.

Bootblock Initialization Code Checkpoints

The Bootblock initialization code sets up the chipset,memory, and other components before system memory is available. The following table describes the type of checkpoints that may occur during the bootblock initialization portion of the BIOS.

NOTE: Please note that checkpoints may differ between different platforms based on system configuration.Checkpoints may change due to vendor requirements,system chipset or option ROMs

from add-in PCI devices.

Checkpoint

Description

 

 

Before D0

If boot block debugger is enabled, CPU cache-as-RAM functionality is enabled at this point.

 

Stack will be enabled from this point.

 

 

D0

Early Boot Strap Processor (BSP) initialization like microcode update, frequency and other

 

CPU critical initialization. Early chipset initialization is done.

 

 

D1

Early super I/O initialization is done including RTC and keyboard controller. Serial port is

 

enabled at this point if needed for debugging. NMI is disabled. Perform keyboard controller

 

BAT test. Save power-on CPUID value in scratch CMOS. Go to flat mode with 4GB limit and

 

GA20 enabled.

 

 

D2

Verify the boot block checksum. System will hang here if checksum is bad.

 

 

D3

Disable CACHE before memory detection. Execute full memory sizing module. If memory

 

sizing module not executed, start memory refresh and do memory sizing in Boot block code.

 

Do additional chipset initialization. Re-enable CACHE. Verify that flat mode is enabled.

 

 

D4

Test base 512KB memory. Adjust policies and cache first 8MB. Set stack.

 

 

D5

Bootblock code is copied from ROM to lower system memory and control is given to it. BIOS

 

now executes out of RAM. Copies compressed boot block code to memory in right

 

segments. Copies BIOS from ROM to RAM for faster access. Performs main BIOS

 

checksum and updates recovery status accordingly.

 

 

D6

Both key sequence and OEM specific method is checked to determine if BIOSrecovery is

 

forced. Main BIOS checksum is tested. If BIOS recovery is necessary,control flows to

 

checkpoint E0. See Bootblock Recovery Code Checkpoints sectionfor more information.

 

 

D7

Restore CPUID value back into register. The Bootblock-Runtime interface module is moved

 

to system memory and control is given to it. Determine whether to execute serial flash.

 

 

D8

The Runtime module is uncompressed into memory. CPUID information is stored in memory.

 

 

D9

Store the Uncompressed pointer for future use in PMM. Copying Main BIOS into memory.

 

Leaves all RAM below 1MB Read-Write including E000 and F000 shadow areas but closing

 

SMRAM.

 

 

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Acer G5900 manual Viewing Bios checkpoints, Bootblock Initialization Code Checkpoints
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G5900 specifications

The Acer G5900 is a powerful and versatile desktop computer that has garnered attention for its performance and capability to cater to both casual users and gaming enthusiasts. Utilizing advanced technologies, the G5900 strikes a balance between efficiency and high-end specifications, making it a suitable choice for a variety of tasks.

At the heart of the Acer G5900 is its robust processor. The device typically comes equipped with Intel or AMD processors, such as the Intel Core i5 or the AMD Ryzen series, ensuring quick processing speeds and reliable performance for multitasking and demanding applications. This processing power is essential for handling everything from everyday productivity tasks to more intensive gaming and content creation.

The G5900 is designed with ample memory options, often featuring configurations with up to 16GB of RAM. This is particularly beneficial for users who run multiple applications simultaneously, as it allows for smooth transitions and swift response times. The option to expand memory further adds to its longevity and adaptability, catering to evolving user needs over time.

Storage options on the Acer G5900 include both traditional HDDs and faster SSDs, with capacities ranging from 512GB to 2TB. This flexibility allows users to choose a setup that best fits their requirements, whether they prioritize speed or storage capacity. The inclusion of an SSD can significantly enhance boot times and application loading, elevating the overall user experience.

One of the standout features of the G5900 is its graphics capabilities. Depending on the configuration, it can be equipped with dedicated graphics cards from NVIDIA or AMD, making it apt for gaming enthusiasts and creative professionals alike. These graphics options enable the G5900 to handle modern titles and complex software with ease.

Connectivity is also a key aspect of the Acer G5900. The desktop generally comes with multiple USB ports, HDMI outputs, and sometimes even USB-C connectivity, providing ample options for connecting peripherals and external displays. Wireless options, including Wi-Fi and Bluetooth, enhance its versatility, allowing for seamless integration into modern home networks.

In terms of design, the Acer G5900 showcases a sleek and modern aesthetic, with a compact form factor that fits well in various environments. Its efficient cooling system is designed to maintain optimal performance even during heavy usage while ensuring quiet operation.

Overall, the Acer G5900 combines power, versatility, and modern design. With its cutting-edge specifications, ample storage, and graphics options, it stands out as an excellent choice for users looking to enhance their computing experience, whether for work, play, or everything in between.
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