INT 21 - Compaq AG1024.SYS - RGDI - GET DRIVER LOCATION
        AX = 4402h
        BX = file handle for device "$$$$RGDI"
        CX = 0006h (size of returned data)
        DS:DX -> location record (see below)
Return: CF clear if successful
            buffer filled
        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=4403h"RGDI"

Format of location record:
Offset  Size    Description
 00h    WORD    signature 55AAh
 02h    WORD    segment of ???
 04h    WORD    segment of device driver's code

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