Our friends at Applied Acoustics Systems have today announced Tassman 4 has been depreciated and is no longer available for sale.
To cut a long story short, AAS have endeavored to evolve Tassman over almost “20 years”, but the old code archive is proving too difficult and constraining to modify. Instead, they are investing efforts into something new… so, stay tuned! 
Tassman 4 should continue to work without problem on future versions of Windows. On Mac OS, it will start producing warnings in the next version of Mac OS (post High Sierra) and most likely will not work in the following one. This is why, plus the fact that bugs will no longer be addressed nor product updated, AAS have decided to depreciate.
In the long term AAS will be able to provide a better customer experience by focusing efforts on something modern.
For more information and final release version downloads, please see the Tassman 4 FAQ here.
As of today, Objec Delay replaces Tassman 4 in the Modeling collection.
