Is it possible just to upgrade the engine and nothing else? And how much would that cost?
You can, and its free.
Here are the links: http://wiki.logos.com/Getting_Started_with_Logos#Installation_.2b_Indexing
eureka! thx!
I didn't see in this link how to upgrade the basic engine to Logos 5. What did I miss?
http://www.logos.com/installation If you have Vista or later upgrade to Logos 5. If you have Mac Os 10.6 or greater move to Logos 5.
I didn't see in this link how to upgrade the basic engine to Logos 5.
The direct link to the Logos 5 download page is: http://www.logos.com/installation
So how is upgrading for free different from buying the minimal crossgrade?
With the free upgrade you only get the engine, no databases or books.
See http://wiki.logos.com/Upgrade_or_Crossgrade