The Multicore Communications API (MCAPI®) specification defines an API and a semantic for communication and synchronization between processing cores in embedded systems. The purpose of MCAPI, which is a message-passing API, is to capture the basic elements of communication and synchronization that are required for closely distributed (multiple cores on a chip and/or chips on a board) embedded systems. The target systems for MCAPI span multiple dimensions of heterogeneity (e.g., core, interconnect, memory, operating system, software toolchain, and programming language). MCAPI provides a limited number of calls with sufficient communication functionality while keeping it simple enough to allow efficient implementations. Additional functionality can be layered on top of the API set. The calls are exemplifying functionality and are not mapped to any particular existing implementation.