US Patent 7206971 Selectable and updatable computer boot memory

A plurality of selectable memory devices is available for booting a computer processor. The devices may be selected prior to booting, or may be changed upon recognition that the booting process is not proceeding properly. In another use, one device may be reprogrammed with an updated version while keeping the older version present. Once the updated version is functioning properly, the older version may be overwritten so that two known working copies are available.