Section 7: Simple Programming112
Loading a Program
When the HP-41C is in PRGM (program) mode, the functions and operations that are normally executed when you press the keys are not executed. Instead, they are stored in program memory for later execution. All but the following operations can be loaded into program memory for later execution.
CLP (clear program)   SIZE (number of storage registers)
   (correction)   PRGM (program mode key)
BST (back step)   GTO · (go to line number)
SST (single step)   CATALOG (catalog list)
DEL (delete program lines)   ON (continuous power)
ASN (assign)   ON (power on key)
USER (USER mode key)   COPY (copy or download program)
    GTO · · (go to end of program memory)
All other functions are loaded into the calculator as program instructions to be executed later. Functions on the keyboard are loaded by simply pressing the associated keys. Functions not on the keyboard are loaded by assigning the function to a key and pressing that key in USER mode, or using XEQ and the function name—just like you would if you were executing the function manually. (Refer to section 4 if you need to refresh your memory.)
To load the complete program into the calculator:
  1. Press PRGM to place the HP-41C into program mode.
  2. Press g GTO · · to set the HP-41C to an unused portion of program memory.
Using GTO · · . When your press GTO · · , the calculator is positioned to the end of program memory (after the last existing program in program memory), and is ready for you to begin keying in the instructions of our program. The display will show 00 REG nn. The nn indicates the number of registers that are unused in program memory (more about this later).
In addition to positioning the calculator to the end of program memory, GTO · · also checks to see if the last program you keyed in was terminated with an END instruction. If an END was not keyed in as the last instruction of that program, GTO · · automatically inserts one. In this way the HP-41C automatically maintains program memory for you!
You can see that GTO · · is extremely useful. Before you begin keying in a program, simply press GTO · · . When you are finished, press GTO · · and the calculator tells you how many registers are left in program memory before and after you key in your program.