code base relevance 1.X vs 5.X

["Patrick Mc(avery" <spell_gooder_now@...>]

I am trying to study the Lua source code. It is very complex and deeply 
intertwined, it will take me sometime to understand it.

I downloaded 1.0 and it's manual. It seems much simpler. Are the basic 
concepts the same? Would it be wise to study the versions one by one to 
catch up or was there some sort of major rebirth along the way that made 
the old code irrelevant?

Thanks-Patrick