In Classic mode (operating systems 7, 8 and 9) if the machine remains completely frozen you can perform a software reboot by holding down the control, command and Power-Up key. The Power-Up key is at the top or right of the keyboard and is marked by an arrowhead.

# Most Macintosh programs allow you to cancel an action such as printing by pressing the full stop key whilst holding down the command key.
# There is another useful keyboard shortcut you might want to try if the current application is completely frozen. Simultaneously pressing the three keys option, command and esc usually gives you the opportunity to Force Quit the program that you were working in. You can then relaunch the program and continue working, without having to restart the Macintosh completely. Note that any unsaved changes will be lost.