These programs introduced the "virtual building" concept for the first time, were you construct a 3D replica of the project and generate automatic sections, plans and documentation from the model. However these software platforms were ahead of their time. Many had rather small market penetration and were not necessary a commercial success, mainly due to their local market focus (and expensive hardware required to run them).
Why are they important?
It's hard to explain in few words but has to do with the building data base in the software and the way the rectangular prism is used as a building block. (This was re-discovered later, when Sketch-up came about). These programs work different from Autodesk Revit and is this author opinion that their particular implementation of "virtual building" was more intuitive, smarter and more "architectural" then the REVIT will ever be. In these early programs, the virtual building was all geometry, there were no "smart" properties attached to the actual geometry. This earlier approach was and is sufficient for an architect to get the design done versus creating a full database of information attached to geometry (that is the case with REVIT). Feeding so much information into the model makes everything cumbersome and limit the designers to a status of "data entry" operators. Design does not work this way.
Architrion.
The grand daddy of virtual building model - was developed in the '80. It's unclear what company developed first, but was owned at different times by GIMEOR INC, BAGH Technologies and PAGE Technologie later. Some screen shots (collected from internet) are shown below:
BOA.
Some of the members of original team that worked for Architrion development went on to develop BOA, who is the next-generation of Architrion. You can still purchase BOA from here:
http://www.boa-research.fr/
Below are some images for BOA Software, (some courtesy of Architosh.com web site -who is the best site for architects on Mac).
BOA got some attention between 2001 and 2005 from former Architrion users but not much has been heard about and is not clear if is still actively developed. A demo version can be downloaded from the above site.
ArchiTech-PC.
Another wonderful program was (and still is) ArchiteTech-PC. It is developed by EDICAD in France at present time but can be described as a lightweight copy of Archicad. It works just fine for small to medium size projects like houses and light duty commercial projects. Researching for this article it seems that they released a new version "8.xx" who -you can tell - uses newer Windows apis. (Images below collected from Google Images)
Triforma.