INT 15 - EISA SYSTEM ROM - READ FUNCTION CONFIGURATION INFORMATION
        AX = D801h
        CH = function number to read
        CL = slot number (including embedded and virtual)
        DS:SI -> 320-byte buffer for standard configuration data block
Return: CF clear if successful
            AH = 00h
            DS:SI buffer filled
        CF set on error
            AH = error code
                80h invalid slot number
                81h invalid function number
                82h EISA CMOS corrupt
                83h empty slot
                86h invalid BIOS-FW function call
                87h invalid system configuration
        BX destroyed
Note:   call with AL=81h if using 32-bit CS addressing mode instead of 16-bit

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