Infrared sender makes a wireless connection between computers and RCX. With the help of the infrared transmitter programs can be transferred by the computer into the RCX and brought there to the execution.
Infrared sender conveys messages as infrared signals. RCX and
Infrared sender must be able "to see" themselves, so that communication functions. Although a optimal distance for communication is 10-12cm for communication, communication functions under very good light conditions (no stout sunshine etc..) will work over a distance of up to 30 meters away.

The IR tower is connected by the USB connection with the computer and needs no own current supply.

Firmware is programming that is inserted into programmable read-only memory (programmable ROM), thus becoming a permanent part of a computing device. ROBOLAB is based on the standard LEGO RCX-firmware. This very well woven basic RCX program offers many exciting features that allow easy RCX programming in nearly any environment. One of the major firmware qualities is the remarkable system-stability: it is nearly impossible to crash a running RCX.

The firmware is the “operating system” of the RCX. In order for the computer to work with the RCX, you must download the firmware. Downloading the firmware allows communication between the IR Transmitter and the RCX so that you can download new programs. Make sure that there are 6 AA batteries in the RCX unit.