By default the calculator will switch into a low power mode if you leave it waiting for a key press for more than a couple of minutes. *SLEEP can be used to set the amount of time to wait before switching into this lower power mode, disable the automatic power down feature entirely, or go into the low power mode instantly.
When in the low power mode the calculator will only respond to the On key, which will switch it back on. The screen is switched off and the TIME pseudo-variable is not updated. On the TI-83+ series the software-implemented TIME$ variable is not updated either; the TI-84+ has a hardware real-time clock and so is not affected.
Setting the time-out
You can set the calculator to switch off after a particular number of idle seconds by passing a numerical argument to *SLEEP. For example,
would switch the calculator into a low power mode after 10 seconds of inactivity.
The shortest amount of time allowed is 5 seconds. The longest amount of time allowed is 65,535 seconds (over 18 hours). A value of 0 disables the automatic power down completely. The default setting is 120 seconds, or two minutes.
Switching the calculator off instantly
If you don't pass any arguments to *SLEEP the calculator switches into the low power mode instantly.
Disabling the automatic power down
If you pass OFF to *SLEEP the automatic power down is disabled.
This is directly equivalent to *SLEEP 0.
If you wish to reset to the default settings (two minute time-out) you can pass ON to *SLEEP:
This is directly equivalent to *SLEEP 120.