Texas Instruments TI-80 Manual Book page 217

Changing the
Batteries
(Continued)
Replace the plastic battery compartment cover. Turn the
calculator on and adjust the contrast display.
To adjust the display contrast, press and release the 2 key.
To increase the contrast (darken the screen), press and hold
7. To decrease the contrast (lighten the screen), press and
hold 8.
Service and Warranty Information B-7