AS Trains were produced in Paris, France by Messrs Pierre Adenot and René Sennedot, from 1980 until 1990, AS being the initials of Messrs Adenot and Sennedot. Post 1990, a change of ownership resulted in the relaunch of AS as La Rotonde and a new company, ETR (Europe Train Retro). René Sennedot went on to found RVZero, again manufacturing French 0 gauge trains.
The full story of AS and subsequent issues is fully illustrated in the French language book AS une légende en images, published by La vie du Rail.
An excellent article by Bryant Booth appears in Tinplate Times online magazine.