Section 9: Program Interruptions146
Keystrokes Display    
PRGM 
       
  Sets the HP-41C to PRGM mode.
g GTO · · 
  00 REG 40    
  Sets the HP-41C to the end of program memory.
g LBL 
  01 LBL _ _    
   
ALPHA SPHERE ALPHA 
  01 LBLTSPHERE    
  The program name, SPHERE.
g CLX 
  02 CLX     
  Clears the X-register.
R/S 
  03 STOP     
  Stop to key in the radius of the sphere.
3 
  04 3 _    
  Places 3 into X. This value pushes the radius into the Y-register.
g Yx 
  05 Y X     
  Computes r3.
g   
  06 PI    
  The value of pi.
 ×   
  07 *     
  Multiplies r3 by π.
4 
  08 4 _    
   
 ×   
  09 *     
  Multiplies πr3 by 4.
3 
  10 3 _    
   
 ÷   
  11 /     
  Divides 4πr3 by 3.
g GTO · · 
  00 REG 37    
  Ends the program.
PRGM 
  0.0000    
   
Now assign SPHERE to the    key location.
Keystrokes Display    
g ASN 
  ASN _    
   
ALPHA SPHERE ALPHA 
  ASN SPHERE _    
   
  
  0.0000    
   
Run SPHERE to find the volume of a spherical weather balloon with a radius of 21.22 feet. Run SPHERE again to find the volume of an official size ping pong ball with a radius of 1.905 centimeters.