Int 21 Fn 4403  U - Pendos Pendev.sys - ???                                [n]

   AX = 4403h
   BX = file handle for device "$$PENDOS" or "$$PD_REG"
   CX = size of buffer
   DS:DX -> buffer containing ???

Return: CF clear if successful
       buffer filled
   CF set on error
       AX = error code (01h,05h,06h,0Dh) (see #1366 at AH=59h/BX=0000h)
Program: A limited version of PenDOS by Communication Intelligence Corporation,
     which provides pen capability to keyboard-based programs, is bundled
     with IBM DOS 6.1

Note:  this call sets the WORD at offset 1Ah into the device driver request
     header used to call the driver to 0000h.

See Also: AX=4402h"PENDEV.SYS"