There was a download of Ptolemy Ptplot 5.5 on the developer's website when we last checked. We cannot confirm if there is a free download of this software available.
We cannot guarantee that the program is safe to download as it will be downloaded from the developer's website. Before launching the program, check it with any free antivirus software. The most popular versions of the Ptolemy Ptplot are 5.8 and 5.5. This free software is an intellectual property of Ptolemy. The software lies within System Utilities, more precisely Device Assistants.
From the developer:
Ptplot 5.8 is a 2D data plotter and histogram tool implemented in Java. Ptplot can be used as a standalone applet or application, or it can be embedded in your own applet or application. Ptplot is a set of two dimensional signal plotters components written in Java
You may want to check out more software, such as FtG - History of Rome, which might be similar to Ptolemy Ptplot.