By now, you have written a number of stand-alone applications for the Keil evaluation board. In each case, there was only one main( void ) function that was executed, and consequently, there was only one thread or task executing.

The next step is to begin using an operating system that allows you to create multiple tasks. We have discussed in class how multiple threads can be created using the POSIX interface and in the CMSIS RTOS, and how to create tasks in the Keil RTX RTOS.

The distinction between a thread and a task is subtle: it is more related to the purpose. A separate thread is usually thought of performing some operation in parallel, usually with the intention of the thread joining the parent again; while a task is a seperate and parallel sequence of execution without an intention of joining with the parent.

There are a number of topics:

• First, we will have an introduction the to Keil Real-time library (RL).