Section 7: Simple Programming113
Keystrokes Display    
PRGM 
  00 REG 46    
  Places the HP-41C into program
mode.
g GTO · · 
  00 REG 46    
  The HP-41C is now ready for you to
begin programming.
The keys that you must press to key in the program for the area of a circle are:
  g LBL ALPHA CIRCLE ALPHA   
  g X2   
  g     
   ×    
Press the first keys, g LBL , of the program.
Keystrokes Display    
g LBL 
  01 LBL _ _    
   
The digits that appear at the left of the display indicate the program memory line number being shown at any time. We will learn more about ‘‘lines’’ later in this section. Now press the ALPHA keys necessary to complete the instruction.
Keystrokes Display    
ALPHA CIRCLE ALPHA 
  01 LBL TCIRCLE    
   
Any time a program line contains an ALPHA label or ALPHA string, the HP-41C places T (raised t, for ‘‘text’’) in the display following the program line number. Notice that as you press functions keys for the program, the HP-41C prompts you for the input, just like in normal mode operation.
Now load the rest of the program:
Keystrokes Display    
g X2 
  02 X 2    
   
g   
  03 PI    
   
 ×  
  04 *    
   
Now press GTO · · . This places an END at the end of the program (in line 5) and tells you how many registers are left in program memory. Notice PACKING display appears momentarily—packing is covered in detail later.
Keystrokes Display    
g GTO · · 
  PACKING    
  This places an END in line 5 and tells you
 
  00 REG 44    
  how many registers are left in program
memory.
The program for solving the area of a circle (named CIRCLE) is now loaded into program memory.