I/O device drivers play an integral role in DSP and embedded system application development by separating the software components from hardware details. This promotes software reuse, modular design, and co-development of hardware and software, benefits that reduce time-to-market for first generation applications and greatly reduce the level of effort for second generation designs. Many applications must process streaming data, such as samples from an ADC/DAC, frame buffer/grabber, or interprocessor communication device. This paper describes a flexible application programming interface (API) for streaming I/O device drivers for use in real-time applications written with a variety of RTOS kernels.