Module

Model: 123 (for Women's watch) Diameter: 20 mm Thickness: 2 mm
Battery:  LR721 Face: LCD 4 digit Light: NO Year: 1981 Module: Two buttons are used: top right, and bottom right.
Function: Displays hours, minutes, seconds and date. It does not have a built-in light
Info: This module is used in the following model TI-255-20

Here you can see the specific contact the button uses when pressed. Two buttons are used: the top right and the bottom right. The top right button is used to select the time, seconds, and date (day and month), while the bottom right button is used to set the time, day and month. This is the thinnest module used in Texas Instruments watches, only 2mm thick!