Some calculations may take a long time to be performed, making it necessary to interrupt these tasks to regain control of the calculator. newRPL provides two different ways to interrupt the system:

• RPL Break - This is the most common way to interrupt programs, it is performed by pressing simultaneously ON-A-C. The screen will show a message and the soft menu will display several options. Cont will continue the task as if it had never been interrupted (press A to select this choice). Exit will end the current RPL program and return to the stack (press B to select this choice). Notice that this option might leave the stack with objects the program was using internally, and the user will need to clean up the stack manually. *Warmstart* will completely restart the RPL engine (press either C or D while at the same time holding any one of the Shift keys to select this choice). A warmstart is only needed if the running program leaves the system unusable. Finally, **Reset** not only restarts the RPL engine, but also causes a reset of the calculator hardware (press either E or F while at the same time holding any one of the Shift keys to select this choice). This is only necessary if the hardware malfunctions or does not respond.

• User Break - This interrupts the entire system, not only the RPL engine, and it is performed by pressing simultaneously ON-A-F. Cont will continue the task as if it had never been interrupted (press A to select this choice). *Clear Mem* will completely wipe out the entire memory. This is a dangerous and unrecoverable procedure, the only way to recover is through backups. For safety, press either C or D while at the same time holding all three shift keys (Left, Right and Alpha) in order to clear the memory. Pressing only one of the shift keys will perform a warmstart but not clear the memory. Finally, **Reset** causes a reset of the calculator hardware (press either E or F while at the same time holding any one of the Shift keys to select this choice). This is only necessary if the hardware malfunctions or does not respond.