Generally, this disclosure provides methods and systems for secure data protection with improved read-only memory locking during system pre-boot including protection of Advanced Configuration and Power Interface (ACPI) tables. The methods may include selecting a region of system memory to be protected, the selection occurring in response to a system reset state and performed by a trusted control block (TCB) comprising a trusted basic input/output system (BIOS); programming an address decoder circuit to configure the selected region as read-write; moving data to be secured to the selected region; programming the address decoder circuit to configure the selected region as read-only; and locking the read-only configuration in the address decoder circuit.