HP 33s - Manual (Page 179)

Simple Programming 12–21
To clear all programs from memory:
1. Press { e to display program lines (PRGM annunciator on).
2. Press { c { } to clear program memory.
3. The message   @ &  prompts you for confirmation. Press {&}.
4. Press { e to cancel program entry.
Clearing all of memory ( { c {}) also clears all programs.
The Checksum
The checksum is a unique hexadecimal value given to each program label and its
associated lines (until the next label). This number is useful for comparison with a
known checksum for an existing program that you have keyed into program
memory. If the known checksum and the one shown by your calculator are the
same, then you have correctly entered all the lines of the program. To see your
checksum:
1. Press { Y { } for the catalog of program labels.
2. Display the appropriate label by using the cursor keys, if necessary.
3. Press and hold |  to display /checksum and /length.
For example, to see the checksum for the current program (the "cylinder"
program):
Keys:
(In RPN mode)
Display: Description:
{ Y { }  
/
 Displays label C, which
takes 67 bytes.
|  (hold) /  
/
 Checksum and length.
If your checksum does not match this number, then you have not entered this
program correctly.
You will see that all of the application programs provided in chapters 15 through
17 include checksum values with each labeled routine so that you can verify the
accuracy of your program entry.
In addition, each equation in a program has a checksum. See "To enter an
equation in a program line" earlier in this chapter.