The Vectrex is a true standout among classic video game consoles. It has its own built-in vector display. For those of you who don't know what that means, a vector display is capable only of drawing lines rather than pixels, which results in beautifully sharp, bright images. It's one of the more expensive vintage systems to collect for, but well worth it.
The Vectrex uses the Motorola 6809 CPU. I used to have a link posted to the Motorola Literature Order Form here, but the form is no longer at the old URL. The publication number for the MC6809 - MC6809E Microprocessor Programming Manual is M6809PM/AD.