Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The XC Programming Language is a computer programming language developed by XMOS. XC is an imperative programming language with a computational framework based on C. XC programs consist of functions that execute statements that act upon values stored in variables. Control-flow statements express decisions, and looping statements express iteration. The language was designed to exploit the XMOS processor architecture, but is a general-purpose language and implementations for other architectures are in construction. Running XC on other platforms is currently supported by highly-optimised interpretation of the XMOS instruction set. One of the most unusual features of XC is the inclusion of timers and ports in a high-level programming language. One of the great historical weaknesses of high-level programming languages - particularly those based on formal theoretical frameworks such as process calculi or those based on functional programming - is the inability to combine clean high-level constructs with efficient and safe input-output.