The first CAD software I used was VU-3D. Written by Psion software for the Sinclair ZX Spectrum. The software was released in 1982 (shortly before AutoCAD 1.0 was released). Although limited in its application it was a good taster of things to come.
The program was supplied on a single cassette tape with a short list of functions. The inlay card states: "VU-3D is a sophisticated three-dimensional and display program. Using simple commands, the user may create a solid object or set of objects in three-dimensional space, observe, modify, print and store such displays."
3D solid modelling on a home computer in 1982 - quite impressive.