Section 7: Simple Programming115
Keystrokes Display    
g ASN 
  ASN _    
  The HP-41C prompts: Assign what?
ALPHA CIRCLE ALPHA 
  ASN CIRCLE _    
  Assign CIRCLE to which key location?
LN 
  SN CIRCLE 15    
  The CIRCLE function is assigned to row 1, column 5 ( LN ) . You can see the keycode assignment if you hold the key down momentarily.
USER 
  0.9503    
  Places the HP-41C in USER mode. Any functions you have assigned to the keyboard become active. The displayed number remains from the previous example.
10.7 CIRCLE ( LN ) 
  359.6809    
  Since CIRCLE is assigned to LN , when you press LN in USER mode, CIRCLE is executed. The answer is shown in square inches.
Now compute the area or the second circle. But this time, hold the function key down momentarily. Notice that the HP-41C prompts you with the USER mode function name. (When the calculator is set to normal mode and you press and hold the key, the HP-41C prompts you with the normal mode function name.)
Keystrokes Display    
.439
  TCIRCLE    
  Hold the key momentarily.
CIRCLE LN 
  0.6055    
  Square meters.
g CLX 
  0.0000    
   
USER 
  0.0000    
  Takes the HP-41C out of USER
mode.
USER mode execution is that simple! It lets you execute functions you have written just like any other function on the HP-41C, and you control the keyboard location. To completely customize your HP-41C, you simply assign programs and functions to the locations you specify.
Unlike standard HP-41C functions (which can each be assigned to several key locations), you can only assign a program that you have written to a single key location. The last key assignment that you specify is the only one that applies.
Included with your new HP-41C are some aids to help you label the keyboard for USER mode operation. There are plastic overlays on which you can write function names, and there are pre-printed sticky-back labels printed with the name of each standard HP-41C function. When you reassign a function to the keyboard, simply write the function name on