PDP-8-E Simulator 2.0 for Mac was available to download from the developer's website when we last checked. We cannot confirm if there is a free download of this app available.
Please check the Mac app with an antivirus before launch as it is downloaded from the developer's website, and we cannot ensure that it is safe. The application lies within System Tools, more precisely General. The actual developer of this free software for Mac is Bernhard Baehr.
From the developer:
PDP-8/E Simulator is an emulator for the DEC PDP-8/E minicomputer running on the Apple Mac. The simulated machine is a PDP-8/E with 4K words of memory and optionally a KM8-E Memory Extension (with up to 32K words of memory) and a KE8-E Extended Arithmetic Element.
You may want to check out more Mac applications, such as Snow Plow Train Simulator 3D - Russia, Loan Simulator or Farming Simulator 2013, which might be related to PDP-8-E Simulator.