Microsoft just unveiled what some are calling the largest tablet computer you've ever seen. But that's not exactly true.

In the late '70s, researchers at MIT built a tablet that filled an entire room, and there it is in the images above and the video below. It was called the Spatial Data Management System, and although it was enormous, it was an awful lot like a modern tablet or smartphone. It had a touch screen, voice recognition, and multiple apps. It could even make phone calls.

The idea behind the system is simple: We humans are inherently spatial thinkers. "People are really natural explorers of space and manipulators of space," says William Donelson, who created the system as part of his masters thesis in MIT's Machine Architecture Group, the predecessor to today's Media Lab. "If you wander around your city or your neighborhood, you'll remember where things are, and I wanted to incorporate that concept into a database."

Donelson says the team wanted to build a user interface that could mimic the way people organize files on a physical desktop. They weren't the only ones working on this idea at the time: engineers at Xerox PARC in Palo Alto developed an experimental computer with a desktop interface in the mid-70s and released a commercial version in 1981.

But Donelson's Spatial Data Management System had a certain grandeur that those clunky boxes lacked. The user sat in a large armchair dubbed the "Captain Kirk Chair," with dual touchpads and joysticks built into each arm. Two touchscreens—boxy Tektronix color monitors on rolling carts—were positioned on either side, just within reach. One presented what we'd now call the homescreen, an assortment of brightly-colored boxes that opened up different programs when poked by the user. The apps included a calculator, maps, a book reader, and photo and video viewers.

The brains behind all this was network of four minicomputers, packing up to 640KB of combined processing power and 640MB of memory in the original version (more on the tech specs here). The display was a 6 by 8 foot television screen directly in front of the user, and 8 speakers positioned around the room provided surround sound.

A user could also issue voice commands to open an app, initiate a phone call, or record a memo. "Visitors were completely blown away," Donelson says. He says the system was arguably the first multimedia computer. But the primitive chips it used made it a finicky beast. "If it got too hot it wouldn't work, if it got too cool it wouldn't work," Donelson says. "I would spend hours trying to adjust the fans to keep it running."

"Much of what we wanted to do back then has become reality today, now that computers are finally powerful enough and budgets are high enough," Donelson says.

The video below shows the system in action. It's a bit slow by today's standards, so here are a few highlights worth checking out:

1:08 Scrolling through photos. Zooming in and out.

3:02 Flipping through the pages of a book using the trackpad.

4:30 Voice commands to pull up photos and a map on the screen.

5:05 Voice commands to initiate a phone call and find a contact.

7:55 Calculator.

8:48 Maps.

9:37 Playing a video (a clip from the TV show Columbo) and using the touchscreen to control the audio language and playback speed.