PA0465 Console Scientific Calculator Program

  Interrupting under the field labelled 'TV keypad' will      
  open a window containing a keypad on the lower half of      
  the screen. This keypad can be used to make calculations    
  much as you would on a handheld calculator. The 'N'         
  (enter operand) and 'O' (enter operator) allow sequential   
  entry of values into the calculation line (line 7). The     
  'E' key puts everything in scientific notation mode while   
  the 'e' key permits entry of a value in scientific          
  notation. The 'I' key calculates the inverse of the operand.
  The 'R' key calculates the square root of the operand.      
  The 's', 'c', and 't' keys return sine, cosine, and         
  tangent values respectively. The 'D' key latches and        
  allows one to switch between degree and radian modes        
  (When the switch is lit you are in degree mode.). The       
  'a' key is another latching key, and when it's on the       
  inverse trigonometric functions are invoked.                
  Note: When in TV keypad mode the touch panel is deactivated.