INT 1A - Intel PCI BIOS v2.0c - PCI BUS-SPECIFIC OPERATIONS
        AX = B106h
        BL = bus number
        EDX = Special Cycle data
Return: CF clear if successful
        CF set on error
        AH = status
            00h successful
            81h unsupported function
        EAX, EBX, ECX, and EDX may be modified
        all other flags (except IF) may be modified
Note:   this function may require up to 1024 byte of stack; it will not enable
          interrupts if they were disabled before making the call
SeeAlso: AX=B186h

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