RT-Thread RTOS is a real-time operating system for 16-bit to 32-bit microcontrollers, with components which include a hard real-time kernel, a command line shell, a device virtual file system, and a graphic user interface. RT-Thread/GUI is a graphic user interface integrated with RT-Thread. It provides a multi-window, multi-thread graphic user interface. Rich widgets are implemented in RT-Thread/GUI, such as label, button, checkbox, textbox, etc. The typical RAM usage of RT-Thread/GUI is less than 20kB RAM.