Secure Boot via Write-Once Register and ROM Flash Segmentation

The patent segments the memory system into two distinct parts: flash memory for storing upgradable BIOS code and a read-only memory (such as EEPROM or ROM) for storing immutable security verification codes. This segmentation allows the system to maintain both adaptability (through flash memory updates) and reliability (through read-only security verification), resolving the contradiction between flexibility and security.

The patent implements preliminary action by executing security verification codes from read-only memory before executing the BIOS code from flash memory during the boot process. This preliminary security check is integrated into the existing boot sequence, adding protection without fundamentally redesigning the boot process. The CPU automatically executes the verification code first, then proceeds to execute the BIOS code if verification succeeds, thus maintaining relative simplicity while enhancing security.

The patent applies partial action by executing only the essential security verification code from read-only memory before BIOS execution, rather than implementing comprehensive security checks. The verification code is designed to perform only the critical function of checking BIOS integrity, avoiding unnecessary verification steps. This partial verification approach provides sufficient security protection while minimizing the time overhead during the boot process.