If you absolutely need to open old ArtCAM 2012 files, Carveco or Vectric Aspire can import many of them.
These are unofficial and may contain malware or "cracked" versions that are illegal and unsafe. Internet Archive (Wayback Machine): artcam 2012 download link
Autodesk officially stopped all development and sales of ArtCAM in February 2018. While users with existing perpetual licenses can still run the software, Autodesk no longer provides active download links or license server support for older versions like 2012. Official Path for Existing License Holders If you absolutely need to open old ArtCAM