Lenovo ThinkPad 770 Technical Reference Manual for the ThinkPad 770 - Page 80
Header Image, Signature, Version Major or Minor, Length, Checksum, SMAPI BIOS
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Header Image Systems that support SMAPI BIOS must provide the following header image in the F000 segment system ROM area at the 16-byte boundary. The client needs to search and find this SMAPI BIOS header image to get the entry point for the service. Field Signature Version (Major) Version (Minor) Length Checksum Information Word Reserved 1 Real mode 16-bit offset to entry point Real mode 16-bit code segment address Reserved 2 16-bit protected mode offset to entry point 16-bit protected mode code segment base address 32-bit protected mode offset to entry point 32-bit protected mode code segment base address Offset (in Hex) 00 04 05 06 07 08 0A 0C 0E 10 12 14 18 1C Length Value 4 bytes Byte Byte Byte Byte Word Word Word Word Word Word Double words Double words Double words '$SMB' (ASCII) 01h 00h 20h - - - - - - - - - - Signature ASCII Code '$SMB' is stored at the top of the header image. Version (Major or Minor) Indicates the SMAPI BIOS version. Length The length of the header image. Checksum Checksum byte area. The client verifies that this header image is valid by using this checksum; the client should check all header image bytes, and the result will be zero bytes. B-4 SMAPI BIOS