INT 15 - Compaq ROM BIOS 03/08/93 and newer - ???
        AH = E4h
        AL = subfunction
            00h get ???
                Return: CF clear
                        AH = 00h
                        CX = 0000h
                        BX = ??? (read from [XBDA:0094h])
            01h,02h unsupported by this ROM version
                Return: CF set, AH = 86h
            80h,90h,A0h,B0h,C0h,D0h,E0h,F0h set ???
                Return: CF clear
                        AH = 00h
                        CX = 0000h
                        BX = ???
            81h,91h,A1h,B1h,C1h,D1h,E1h,F1h unsupported by 3/8/93&4/8/93 ROMs
                Return: CF set, AH = 86h
Notes:  functions 80h/90h/etc. are not supported by the 4/8/93 EISA System ROM
        these functions are not supported by the 7/26/93 LTE Lite 386 ROM

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