Abstract: A circuit and method are provided for initializing configuration registers in a bus bridge controller so that peripheral devices can acquire functionality prior to initialization by a normal system Basic Input/Output System (BIOS) routine. The initialization information is stored in a supplemental configuration Electronically Erasable Programmable Read Only Memory (EEPROM), separate from a conventional system BIOS ROM. In addition, the register configuration information is stored in a flexible format so that only certain devices are pre-configured, or that certain devices are initialized before others. The invention has particular usefulness in personal computing systems which include a Peripheral Component Interconnect (PCI) bus, an ISA bus, and a system management bus (SMB) for providing access to the EEPROM.