CALL xxxxh:xxxxh - Intel BIOS(Basic Input/Output System) A set of standardized calls giving low-level access to the hardware. The BIOS is the lowest software layer above the actual hardware and serves to insulate programs (and operating systems) which use it from the details of accessing the hardware directly. Upgrade InstallCheck: scan paragraph boundaries from 0F0000h to 0FFFFFh for signature string "$IBU" (see #F0023) SeeAlso: INT 15/AX=D042h/BL=00h !!! IAL\PROCESSR\PPROBIOS.PDF page 60 Format of Intel BIOS(Basic Input/Output System) A set of standardized calls giving low-level access to the hardware. The BIOS is the lowest software layer above the actual hardware and serves to insulate programs (and operating systems) which use it from the details of accessing the hardware directly. Upgrade header: Offset Size Description (Table F0023) 00h 4 BYTEs signature "$IBU" 04h BYTE IBU specification version (currently 01h = 1.0) 05h BYTE length of entire header structure in bytes (currently 17h) 06h BYTE checksum (forces 8-bit sum of all header bytes to 00h) 07h DWORDDoubleword; four bytes. Commonly used to hold a 32-bit segment:offset or selector:offset address. real-mode entry point address 0Bh WORD offset of 16-bit protected mode entry point 0Dh DWORDDoubleword; four bytes. Commonly used to hold a 32-bit segment:offset or selector:offset address. segment base address of 16-bit protected-mode entry point 11h WORD real-mode data segment address 13h DWORDDoubleword; four bytes. Commonly used to hold a 32-bit segment:offset or selector:offset address. segment base address of 16-bit protected-mode data segment Notes: calls from 32-bit protected mode may be made to the 16-bit entry point, but must ensure that any stack arguments are pushed as 16-bit values instead of 32-bit values the entry point uses standard C calling conventions to implement functions prototyped as int far (*entrypoint)(int function, ...)