Download Pd from http://puredata.info/.

There are two main versions of Pd.

• Pd vanilla: the core written by Miller Puckette (focused on audio signal and MIDI processing).
• Pd extended:  this version of Pd also contains libraries written by the community.

For this introductory course, Pd vanilla will suffice. But feel free to download Pd extended. I will be working with Pd vanilla, Pure Data 0.45.4