An XCore processor runs multiple real-time threads simultaneously. Each thread has access to a set of general purpose registers, gets a guaranteed share of the processing power, and executes a program using common RISC-style instructions. Each thread can execute simple computational code, DSP code, control software (taking logic decisions, or executing a state machine) or handle I/O operations.

Threads share a memory and can use this shared memory to exchange data, or they can use channels to exchange data and synchronise. If shared memory is used, then threads can use single-cycle lock instructions in order to co-ordinate access. If channels are used for communication, then single cycle instructions can transfer a word of data.

I/O pins can be set and sampled in a single instruction. Simple input and output instructions transfer data to or from I/O ports. More complex use allows data to be serialised and deserialised, enabling the processor to keep up with high speed data streams. The ports can timestamp data and synchronise transfers with an external clock.

The XCore is event driven and threads waiting for events do not consume any processing resources. An event can be the completion of a communication or I/O operation, the release of a lock or a timer reaching a programmed time. Threads can wait for any one of a set of events. The first event will cause the thread to start in a single instruction.