A Teradata node requires three distinct pieces of software:

1)Trusted Parallel Application (TPA)
2)Parallel Database Extensions (PDE)
3)Operating System

The Parallel Database Extensions (PDE) software layer was added to the operating system by NCR to support the parallel software environment.

A Trusted Parallel Application (TPA) uses PDE to implement virtual processors (vprocs). The Teradata RDBMS is classified as a TPA. The four components of the Teradata TPA are:

AMP
PE
Channel Driver (Channel Driver software is the means of communication between an application and the PEs assigned to channel-attached clients)
Teradata Gateway ( Teradata Gateway software is the means of communication between an application and the PEs assigned to network-attached clients. There is one Teradata Gateway per node)