INT 21 U - Quarterdeck - HOOKROM.SYS - GET HOOKED VECTOR TABLE
        AX = 4402h
        BX = file handle for device "HOOKROM$"
        CX = 0004h
        DS:DX -> DWORD buffer for address of hooked vector table (see below)
Return: CF clear if successful
            DS:DX buffer filled
        CF set on error
            AX = error code (01h,05h,06h,0Dh) (see AH=59h)

Format of hooked vector table entry:
Offset  Size    Description
 00h  5 BYTEs   FAR jump to actual interrupt handler
                (end of table if first byte is not EAh)
 05h    BYTE    interrupt vector number