We have designed a hardware-assisted interprocessor communication (IPC) mechanism that can reduce the communication overhead of embedded microcontrollers by a factor of 30 or more. The real-time communication mechanism allows processes to exchange data in a predictable and timely manner, with minimum overhead, in both single and multiprocessor environments. The hardware assist is a modified DMA (direct memory access) architecture. We combined it with an existing software-based real-time communication mechanism that takes advantage of the fact that, in control systems, IPC requirements for most processes in the system are small and known a priori. The mechanism is designed especially for digital control systems that can be defined as a collection of software components that follow the port automaton model, for which it is more important to always obtain the most recent data, rather than always needing to process every data item.