For simple applications, RTOS is usually a kernel but as complexity increases, various modules like networking protocol, debugging facilities, device I/Os are included in addition to the kernel.

The general architecture of RTOS is shown in the figure:

An operating system generally consists of two ports: kernel space and user space.

RTOS kernel acts as an observation layer between the hardware and the applications.

Kernel is the smallest and central component of an operating system. Its services include managing memory and devices and to provide an interface for software applications to use the resources.

Six types of common services provided by the kernel are shown below in the figure: