The three large holes in the center are the light detectors. The two holes nearer the front are infrared emitters. The center front hole is the infrared detector.The center top hole is called the "Pen Port", enabling the robot to "scribble": Place a marker in that hole, and the marker will touch the ground on the other side, thus drawing a line as the robot moves. The grilled hole below that is the speaker. Below the "Scribbler Robot" logo we have 4 LED lights, used for communication and status.
Below the LEDs, we have a 9-pin female serial connector - this "Programming Port" is what the unit uses to communicate with a computer for programming. To the left of the Programming Port is the red reset button. To the right of the Programming Port is the Scribbler's On / Off switch.
The battery the lower half (the Scribbler requires 6 AA batteries, and rechargeables work fine). Above the center "Pen Port" we see the four infrared line sensors used for detecting lines on the ground as the unit moves.