Int 21 Fn 4402  U - IBM System 36/38 Workstation Emulation - Vdi.sys - Ge  [I]

   AX = 4402h
   BX = handle for character device "GDMS"
   CX = number of bytes to read (>= 4)
   DS:DX -> buffer (see below)

Return: CF set on error
       AX = error code (see AH=59h)
   CF clear if successful
       AX = number of bytes read

Format of returned data:
Offset Size    Description
 00h  4 BYTEs  ???
 04h   DWORD   pointer to ???
 08h  4 BYTEs  ???