INT 21 - Compaq AG1024.SYS - RGDI - IOCTL OUTPUT
        AX = 4403h
        BX = file handle referencing device "$$$$RGDI"
        DS:DX -> request packet (see below)
        CX ignored
Return: CF clear if successful
            AX destroyed
            data buffer filled (if applicable)
            first word of request packet set to number of bytes of data
              available (amount returned is smaller of this and requested
              amount)
        CF set on error
            AX = error code (01h,05h,06h,0Dh) (see AH=59h)
Program: AG1024.SYS is a device driver for the Advanced Graphics 1024 adapter
SeeAlso: AX=4402h"RGDI",AX=4403h"CPQ_MGES"

Format of request packet:
Offset  Size    Description
 00h    WORD    function
                0000h get entry points
                0001h get ???
 02h    DWORD   address of buffer for returned data

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