International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Today’s large-scale signal processing systems impose massive bandwidth requirements on both internal and external communication systems. Most often, these bandwidth requirements are met by scalable input/output architectures built around high-performance, standards-based technology. Several such technologies are available and are in common use as internal and/or external communication mechanisms. This paper provides an overview of some of the more common scalable technologies used for internal and external communications in real-time data acquisition systems. With respect to internal communications mechanisms this paper focuses on three ANSI-standard switched fabric technologies: RACEway (ANSI/VITA 5-1994), SKYchannel (ANSI/VITA 10-1995) and Myrinet (ANSI/VITA 26-1998). The discussion then turns to how Fibre Channel, HiPPI, and ATM are used to provide scalable external communications in real-time systems. Finally, glimpse of how these technologies are evolving to meet tomorrow’s requirements is provided.