Squeak is a free object-orientated software environment. One of its features is to have great effects on children's learning of information technologies. There are extramural classes using Squeak as educational materials, where it helps children learn the basic principles of robotics. This study aims at creating and developing a system for controlling robots from Squeak. First, a communication protocol between Squeak and the microcomputer was decided. After that, the microcomputer was programmed based on the protocol. The program was verified by using an existing morph which provides serial communication features. In an earlier study, two problems were pointed out: The serial cable connecting the computer and the robot interfere with free movement of the robot, and the existing protocol is not able to process conditional branching. Therefore the protocol was reexamined and the morph was extended. Major improvements are as follows: The length of an instruction word was changed from 1 byte to 2 bytes. The system that executes programs preliminarily written on the flash data memory was introduced as the batch processing system. With the new system, the serial cable can be removed while the microcomputer is running in batch processing mode. Moreover, it became possible for the system to process basic conditional branching. The morph was extended based on a class of SerialPortMorph so that it can easily process added instructions. In conclusion, the robot's movement became freer and more flexible. The control system was improved without losing its original usability.