So Nintendo's first home console was the Nintendo Entertainment System/Famicom, right? Nope. The company's first foray into home video gaming actually dates back to 1977, six whole years before the Famicom was released in Japan.
That "home console" was actually a series of machines called "Color TV", which were living room versions of popular arcade games of the time. Five of these consoles were produced between 1977 and 1980, and despite never having been released outside of Japan, proved to be a surprise success for the Kyoto-based company.
The first of them, released in 1977, was called "Color TV Game 6". Snappy! It was essentially a Pong clone, in that you used dials to move a platform around hitting a ball. The "6" in the machine's name comes from the fact it included six different ways to play
Color TV Game 6 is notable for being not only the first home video game machine designed and built by Nintendo (in a partnership with Mitsubishi), but one that established a company ethos that has remained largely to this day: consoles must be sold at a profit. The Color TV Game 6 was sold at a loss for Nintendo, so a key feature of future versions of the machines would be that, like the Wii today, it would need to make the company a profit with every one sold.
The Color TV Game 6 sold an impressive 350,000 units in Japan before it was followed in 1978 by the cheaper, bigger and better Color TV Game 15. Again, the number referred to the variety of types of game available, and again, that game was Light Tennis, though with the 15 being both cheaper than the 6 and featuring detachable control pads, it was a much more successful unit, selling over 700,000 units.
Less than a year later, Color TV Racing 112 was released, this time leaving Light Tennis behind for a driving game which had you dodging oncoming traffic. It had the controller - a steering wheel and gearstick - literally built into the machine itself, and if you think think that was a stupid idea, take it up with legendary Mario and Zelda creator Shigeru Miyamoto, who helped design the hardware's casing.
In 1979, Nintendo released Color TV Block Kusure, which was another clone of an existing title, this time of arcade game Breakout. Miyamoto was again responsible for the hardware's outer design, which is notable for also being the very first home video game machine Nintendo designed and constructed entirely on its own (the previous models having been a cooperative effort with Mitsubishi).
The final console in the series was called Computer TV Game, and was a home version of Nintendo's arcade adaptation of the board game Othello. It wasn't a port; it was literally a home version of the arcade game, shipping with the same circuitry that you'd find in the commercial edition. Miyamoto again helped on design (including the packaging!).
They may not have fit the traditional model of what we'd call a console, since they shipped with in-built games rather than a capacity to play titles off an external storage medium, but as they were video game machines designed to be plugged into the TV and played at home, I'd say they're close enough.
While initially primitive, each machine introduced new innovations, whether they be in reducing production costs, implementing control pads or giving designers like Shigeru Miyamoto (who at the time was an artist with an industrial design degree) a chance to cut their teeth. Which they did: the next home machine Nintendo released was the Famicom/NES, and that seemed to turn out OK for the company.
If you're interested in picking one up, know that because of their rarity (they were never released outside of Japan and haven't fared so well over the years), they're expensive: a copy of Computer TV Game recently sold for USD$3000.
This has been a historical post on Nintendo's hardware business. For something a little seedier, you should check out Brian's piece on Nintendo's flirtations with love hotels and the Yakuza.