I am the proud owner of a Vectrex, a self-contained unit with a 9 inch monochrome vector display, a 6809 brain, 1k RAM, an 8k ROM, and very little else - it's a cartridge based machine. The sound is quite good for such a small box, and it has both a sound chip and a DAC. (Now, actually, I'm not so proud, because my Vectrex is broken, and has been since shortly after I bought it - it was an unsuccessful product, many units were sold off when it was discontinued, and a friend bought one then sold it on to me.)

To make something of this machine, one must do something by way of making a cartridge for it, preferably an intelligent one. Here are a couple of projects:
http://vectrex32.com/ - 200MHz PIC32
http://spritesmods.com/?art=veccart&page=2 - 100MHz ARM

Doom on a Vectrex (video)


I've a feeling there was a keyboard peripheral for the Vectrex, at least a planned one, which means it could have been a home computer... and indeed there was support for, or an idea for, spinning colour filter glasses to upgrade the monochrome 2D display to a dazzling (and strobing) 3D colour display.

Refs:

https://en.wikipedia.org/wiki/Vectrex
Troubleshooting guide (18 page pdf)
Service Manual (52 page pdf)
Service Manual (34 page pdf)

Hat tip to Jeff for prompting this post. Really, I think he was trying to get me to fix the thing... and fit a 6309!

Someone at my hackspace has two of those, one of which we repaired -- I think we had to replace the main crystal and a 6522 (?)

Be very careful after opening the case. The display side of the electronics runs are hi voltages.

Its a very unique design but not an especially good one.

> two of them
Excellent!

> hi voltage
Yes, that's been the main thing putting me off - the other being disinterring it from whichever dusty spider nest it's in.