The History of the Vectrex
Matt Barton writes "Gamasutra is featuring an illustrated history of the Vectrex. The article goes in-depth on the development, specs, and impact of the unusual but innovative vector-based platform. We also discuss the modern Vectrex homebrew scene and collectors' market."
It's been a little while since I've programmed one, but you program it in assembly. The machine has quite a few built-in functions in ROM to handle the most common vector operations (a lot more than most vintage consoles). You can essentially say moveto(x,y). It also has routines to draw text, center/re-orient the beam, play sound, etc. More info here.