Robotics has been growing rapidly, especially in industry, to do many human works. It’s crucial to make system programming that can control the movement of each of the robot’s part, so it can work properly. In this research, the EDARM ED-7100 arm robot controller has been redesigned using AT89S52 microcontroller consisting 3 operation modes, i.e. manual, automatic, and computer-based. In manual mode, a user can move a part of the robot by pressing one of the buttons on the controller box, much like the previous controller. There are 8 buttons available for 4 movement pairs, i.e. body, arm, wrist, and gripper. In automatic mode, arm robot moves by following a sequence that has been preprogrammed in microcontroller, to do the “get and move to another place” motion sequence. In the computer-based mode, user can control the arm robot through the interface program which was created in Visual Basic. The developed arm robot controller has been functioning as well as the previous one and is enhanced with several additional functions.