A Scalable Data Acquisition System has been designed using Chorus, a modular distributed real-time operating system and serial point-to-point links. The SDAS is based on data-driven clients and servers which allow scalability of the software through their distribution and hierarchy. The communication between clients and servers is underpinned by the Inter Process Communication (IPC) facilities of the Chorus operating system. The IPC o ers communication indirection; the communication interface of clients and servers remains constant across a distributed system independentof the placement of processes on processors. The scalability of the hardware is achieved using point-to-point serial links.