The sensor board

1. Connector to the main board
2. Connector (under the board) to the motor board
3. Connector to the sensors
4. 74HC244 - Reads the user pushbutton switches
5. 74HC138 - Decodes the addresses for I/O functions
6. 74HC574 - Sends data to the motor driver chips
7. 74HC245 - Reads data from the IR sensors
8. Buffer
9. LM339 Comparators
10. Adjusts the sensitivity of the sensors.