PianoRoll 5.6 for Mac could be downloaded from the developer's website when we last checked. We cannot confirm if there is a free download of this app available. The unique ID for this program's bundle is org.musickit.PianoRoll.
The actual developer of this free software for Mac is Thomas Stone. We recommend checking the downloaded files with any free antivirus. The most popular versions among the program users are 5.6 and 5.0. The software lies within Education Tools, more precisely Teaching Tools.
From the developer:
This program generates quirky piano music. It was made using MAX / MSP. It's useful to generate piano music to set atmospheric moods, perfect for halloween. It is also provides access to musical composition without having to have learn how to read music.
You may want to check out more Mac applications, such as AscoGraph, which might be related to PianoRoll.