Section 3: Automatic Memory Stack and ALPHA Register46
Try it now:
Keystrokes Display    
X Y   2.0000    
Notice that whenever you move numbers in the stack using one of the data manipulation functions the actual stack registers maintain their positions. Only the contents of the registers are shifted. Later, in section 6, you will learn how to exchange the X-register with any other storage register in the HP-41C.
The ENTER  Key
When you key numbers into the calculator, you must tell the calculator when you have finished keying in one number and are ready to key in the next number. You do this using the ENTER  key.
In addition to letting the calculator know you are finished keying in a number, pressing ENTER  also moves the number into the stack. Here is what happens when you key in a number and press ENTER :
Keystrokes Display    
987.3  987.3 _   The number.
ENTER    987.3000   The number.
First, when you key in the number, the stack is changed...
  ...from this... this.  
  T  4.0000   T  3.0000  
  Z  3.0000 Z  1.0000  
  Y  1.0000 Y  2.0000  
  X  2.0000 X  987.3000  
Then, when you press ENTER , the number is pushed into the Y-register. The contents of the stack are then changed...
  ...from this... this.  
  T  3.0000   T  1.0000  
  Z  1.0000 Z  2.0000  
  Y  2.0000 Y  987.3000  
  X  987.3000 X  987.3000  
The value in the X-register is duplicated and pushed into the Y-register. the numbers in Y and Z are pushed up to Z end T, respectively, and the number in T is lost off the top of the stack.