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Int 15h, C0h            Return System Configuration                      many

    Reports the machine model number, sub-model number, BIOS revision
    level, and other hardware-specific attributes.

        Entry   AH = C0h

        Return  CF      Set if error, else cleared
                AH    = 0
                ES:BX = Pointer to a System Descriptor Table

    ------------------------------------------------------------------

    This service is not available for the PC, PCjr, XT dated 11/08/82,
    and the AT dated 1/10/84. Use the return state of AH to determine
    if the service is returning valid information.


        System Descriptor Table

        Description          Length (byte)   Value
        Table length            1              8
        System model number     1              ?
        Sub-model number        1              ?
        Bios Revision level     1              ?
        Feature Information     1              ?
        Reserved                4              0


        Feature Information

        7 6 5 4 3 2 1 0
        x . . . . . . .     Fixed Disk BIOS uses DMA channel 3
        . x . . . . . .     2nd interrupt chip present
        . . x . . . . .     Real-time clock present
        . . . x . . . .     Keyboard intercept called in Int 09h
        . . . . x . . .     Wait for external event supported
        . . . . . x . .     Reserved
        . . . . . . x .     Reserved
        . . . . . . . x     Reserved


    ------------------------------------------------------------------

    The XT dated 1/10/86 has a bug in its Feature Information. It
    incorrectly states that the second interrupt chip is present (bit
    6 is set) and that the fixed disk BIOS doesn't use DMA channel 3
    (bit 7 is clear). Both of these are incorrect. To test for this
    condition, if the model number is FBh and the BIOS level is 1,
    then ASSUME that the Fixed disk BIOS does use DMA channel 3 and
    the second interrupt chip is not present.

    Programs using the DMA channel 3 presence must also be aware that
    other adapters may be using this channel, such as the IBM Network
    Adapter, which will not be reflected in the Feature Information
    byte.

    See Int 15h, Service 4Fh, for more information on Keyboard
    intercept (bit 4 of the Feature Information byte) and see Int 09h
    for more information of the hardware keyboard interrupt.

    See Int 15h, Service 41h, for more information on the Wait for
    External Event (bit 3 of the Feature Information byte).