Abbreviation for Time Division (or Domain) Multiplexing. TDM dates at least as far back as early telephone and telegraph systems, where multiple signals were able to exist on one cable by way of a complex mechanical relay system that caused different signals to actually “appear” on the line at different instances in time. The TDM concept was applied to audio by Digidesign years ago in the development of their Pro Tools product. The product was developed from the ground up to have an internal timing resolution of 256 times the sample rate. Among other things this provided an innate ability for Pro Tools to carry out up to 256 different operations per sample (see also Super Clock). Shortly after the release of Pro Tools 2.0, TDM became positioned as an architecture that would provide an internal 256 channel, 24-bit routing matrix implemented in the Pro Tools software. By adding other hardware resources, such as DSP chips, it became possible to route audio to and from various places in a system where other processes could be applied to the audio. This provided a foundation to begin to have plug-ins and lots of other real time audio routing capabilities in Pro Tools.