An apparatus for loading BIOS stored on a direct access storage device in a personal computer system, the system comprising direct access storage device, and a processor card removably mounted to a planar board. The processor card comprises a system processor and ROM memory, while the planar board includes a main memory. A master boot record is stored on the direct access storage device. The master boot record contains a data segment and an executable code segment, the data segment representing the hardware configuration of the personal computer system. A first portion of BIOS included in the ROM memory initializes the system and causes loading of the master boot record into main memory. This first portion of BIOS further compares the hardware configuration data of the master boot record with the hardware configuration data in the ROM memory to verify compatibility with the system processor. Once compatibility of the master boot record with the system processor is verified, the first portion of BIOS transfers control to an executable code segment of the master boot record to effect loading of the remaining portion of BIOS into main memory, and the first portion of BIOS is discarded.