What looks for ram video and a keyboard when the computer is turned on?

When a computer is turned on, the BiOS (Basic Input/Output System) or UEFI (Unified Extensible Firmware Interface) performs a Power-On Self-Test (POST). During this process, it checks for essential hardware components, including RAM, video card, and keyboard, to ensure they are functioning properly. If any of these components are missing or malfunctioning, the BiOS/UEFI may emit error codes or beep sequences to indicate the issue. Once all checks are passed, the system proceeds to boot the operating system.