Interrupt  05h Print Screen
(0:0014h) service dumps the screen to the printer. Invoked by Int\09 for
          shifted key 55 (PrtSc). Automatically called by keyboard scan when
          PrtSc key is pressed. Normally executes a routine to print the
          screen, but may call any routine that can safely be executed from
          inside the keyboard scanner. Status and result byte are at
          Address -0050:0000.
(internal) BOUND check failed (80186/80286)
	   Generated by BOUND instruction when the value to be tested is less 
	   than the indicated lower bound or greater than the indicated upper 
	   bound. 
 
entry   AH      05h 
return  absolute address 50:0    
	00h     print screen has not been called, or upon return from a call  
		there were no errors. 
	01h     print screen is already in progress. 
	0FFh    error encountered during printing. 
note 1) Uses BIOS services to read the screen 
     2) Output is directed to LPT1 
     3) Revectored into GRAPHICS.COM if GRAPHICS.COM is loaded