INT 1A - Intel PCI BIOS v2.0c - WRITE CONFIGURATION DWORD (32-bit)
        AX = B18Dh
        BL = bus number
        BH = device/function number (bits 7-3 device, bits 2-0 function)
        DI = register number (multiple of 4 less than 0100h)
        ECX = dword to write
Return: as for AX=B10Dh
SeeAlso: AX=B10Dh

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