Stopping or Interrupting a Program

Programming a Stop or Pause (STOP, PSE)

Pressing (run/stop) during program entry inserts a STOP instruction. This will display the contents of the X-register and halt a running program until you resume it by pressing from the keyboard. You can use STOP rather than RTN in order to end a program without returning the program pointer to the top of memory.

Pressing during program entry inserts a PSE (pause) instruction. This will suspend a running program and display the contents of the X– register for about 1 second — with the following exception. If PSE immediately follows a VIEW instruction or an equation that's displayed (flag 10 set), the variable or equation is displayed instead — and the display remains after the 1–second pause.

Interrupting a Running Program

You can interrupt a running program at any time by pressing or . The program completes its current instruction before stopping. Press (run/stop) to resume the program.

If you interrupt a program and then press , , or , you cannot resume the program with . Re-execute the program instead (label line number).

Error Stops

If an error occurs in the course of a running program, program execution halts and an error message appears in the display. (There is a list of messages and conditions in appendix F.)

To see the line in the program containing the error–causing instruction, press  . The program will have stopped at that point. (For instance, it might be a instruction, which caused an illegal division by zero.)