This one is a cute little toy! It's a so-called 'nomadic workstation', ie. a portable computer that has a LCD panel built into the case.
It has a curious version of the bwtwo frame buffer that drives both the internal display and the external video connector. But unlike the original bwtwo, which worked only with TTL monitors, this one works with normal fixed-sync monitors -- still monochrome, yes, but you don't need a special monitor.
The Voyager came in two different models, one with a 14" monochrome display (and a bwtwo frame buffer) at 1152x900, and one with a 12" colour display (with a cgsix frame buffer) at 1024x768, and they were also sold without display.
If you mount a monochrome display on a Voyager and get a picture with every eightth pixel column missing, this doesn't mean that your display is broken -- you just have a cgsix frame buffer, which is intended for the colour display. Installing a replacement bwtwo is easy, but obtaining is probably very close to impossible.
The Voyager has 16MB memory on-board, and can be expanded with two 16MB or 32MB memory cards, so the maximum amount of RAM it can take is 80MB. It uses a proprietary format for the memory that looks a little like a PCMCIA card, but with the connector on the long edge. These cards are another thing that's impossible to find, as they were only ever used in the Voyager and are not produced anymore.
Opening a Voyager is not very difficult if you know how. You first have to remove four screws (two on each side of the case.) The screws are ususally hidden beneath rubber caps, and one is under the cover for the power supply. After you remove them, you can slide the side covers off, and then remove the rear cover. Then you can remove the two screws on the top to remove the display (or the display cover, if you have one without display.), and get the front cover off. They usually require a little force, but there are no additional screws to remove.