Power-On Self-Test (POST) Memory Count During the boot process, from which location does the system start counting memory?

Introduction / Context:
On power-up, a PC performs a Power-On Self-Test (POST) to check essential hardware, including system memory. Knowing where the memory count begins clarifies troubleshooting for RAM-related boot issues.

Given Data / Assumptions:

• Standard PC architecture with DIMMs installed on the motherboard.
• Optional add-in memory expansion boards are rare in modern systems.
• Cache memory and video memory are separate from main system RAM.

Concept / Approach:

The POST initializes the chipset and begins testing main system memory located on the motherboard. Video adapter memory and caches are not counted as part of the base system RAM tally; they are tested separately (if at all) by device-specific routines. Therefore, the memory count starts with the system board RAM.

Step-by-Step Solution:

Verification / Alternative check:

BIOS documentation and diagnostic screens show system memory count reflecting motherboard RAM first, before peripheral initialization. Memory test programs run after POST confirm base RAM locations.

Why Other Options Are Wrong:

Expansion memory board: Not standard in contemporary PCs; even when present historically, base memory is still on the system board. Video adapter: Its VRAM is separate and not part of the system memory count. Cache: Cache is tested differently and is not tallied as system memory. None of the above: Incorrect because the system board is correct.

Common Pitfalls:

Confusing VRAM or cache size with main memory; misattributing POST errors to the wrong device.

Final Answer:

System board