Precision Timed Architectures (PRET) are a recent proposal for designing processors for real-time embedded systems. These processors must guarantee precise worst case reaction time (WCRT) of applications without sacrificing throughput, and must allow the WCRT of programs to be computed simply as well as efficiently. The ob jective of this paper is to propose a new synchronous language based on C, called PRET-C, for programming PRET machines. PRET-C supports synchronous concurrency, preemption, and a high-level construct for logical time. In contrast to existing synchronous languages, PRET-C offers C-based shared memory communications between concurrent threads, that are guaranteed to be thread safe via the proposed semantics. Preemption is also semantically simpler. Programmer can freely mix both logical time (though the notion of logical ticks) and physical time by controlling hardware timers thanks to C libraries. Mapping of logical time to physical time is achieved thanks to the WCRT analyzer and the associated compiler. We also propose the Auckland Reactive PRET processor (ARPRET) that customizes the Xilinx MicroBlaze processor, a general purpose processor (GPP). Together, PRET-C and ARPRET offer an easy, scalable, and efficient solution to the design of precision timed embedded systems.