TDM
Digidesign's Time Division Multiplexing (TDM) technology is the foundation of the Pro Tools professional mixing environment.
TDM Plug-Ins use the dedicated hardware found on the PCI cards of TDM systems.
 

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RTAS

Real-Time AudioSuite Plug-Ins are host-based, relying on the computer's internal processing power to do their job.
Functionally, RTAS Plug-Ins offer many of the real-time benefits of TDM Plug-ins.
Their parameters can change in real-time, they are fully automatable,
and their effects are not permanently written to the audio file.

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AudioSuite

AudioSuite Plug-Ins provide File-based or non-real-time processing, meaning they process or alter the sound file and create a new file with the processed sound. The resulting effect is applied to the entire file.