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INT 10h, 1Bh (27)      Return Functionality Information          PS/2, VGA

     This service returns information about the video equipment and state.

        On entry:     BX          0
                      ES:DI       Address of Buffer to be filled
                                      (see below)

     Buffer contents:
        Offset          Means
        ------          -----
        0               Offset of functionality information
        2               Segment of functionality information
        4               Video mode
        5               Columns on screen
        7               Length of regenerator buffer in bytes
        9               Starting address of regenerator buffer
        0Bh             Cursor position for eight display pages
        1Bh             Cursor type setting
        1Dh             Active display page
        1Eh             CRT controller address
        20h             Current setting of 3x8 register
        21h             Current setting of 3x9 register
        22h             Rows on screen
        23h             Character height in scan lines
        25h             Display Code
        26h             Display Code (alternate)
        27h             Colors supported in current mode
        29h             Display pages supported
        2Ah             Scan lines in current mode
                                0 . 200 scan lines
                                1 . 350 scan lines
                                2 . 400 scan lines
                                3 . 480 scan lines
                                4 - 255 reserved
        2Bh             Primary character block
                                0 . block 0
                                1 . block 1
                                     :
                                255 . block 255
        2Ch             Secondary character block
                                0 . block 0
                                1 . block 1
                                     :
                                255 . block 255
        2Dh             State information
                                Bits 7, 6 reserved
                                Bit  5 = 0 . background intensity
                                         1 . blinking
                                Bit  4 = 1 . cursor emulation active
                                Bit  3 = 1 . default palette loading diabled
                                Bit  2 = 1 . monochrome display attached
                                Bit  1 = 1 . summing active
                                Bit  0 = 1 . all modes on all displays active
        2Eh             Reserved
        31h             Video memory available
                                0 . 64K
                                1 . 128K
                                2 . 192K
                                3 . 256K
        32h             Save pointer state information
                                Bits 7, 6 reserved
                                Bit  5 = 1 . DCC extension active
                                Bit  4 = 1 . palette override active
                                Bit  3 = 1 . graphics font override active
                                Bit  2 = 1 . alpha font override active
                                Bit  1 = 1 . dynamic save area active
                                Bit  0 = 1 . 512 character set active
        33h             Reserved
        3Fh             End

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     This Service returns information about the current video state,
     including most of the settings now active. The information returned by
     this service is lengthy.

     Service 1Bh is usually used only by operating system software. In most
     cases, you can get the information you need with INT 10h service 0Fh,
     return video state.