Ben Heck, creator of the NES Micro, has managed to minituarize the Atari 2600 by using a "very heavily hacked" four switch motherboard. It features a 1.5-inch PS1 LCD display and a convenient top-loading cartridge slot. This custom system is slightly larger than your hand and is powered by six AA batteries. More pics after the jump.
[benheck - ShoutIt]
From the article: "As you can probably tell the buttons/joypad have to fit between the screens' motherboard and the front of the case - not a lot of room. I pulled a dirty trick and put the switches on the bottoms of the buttons themselves, and then they click against the screen's motherboard. Sneaky, to be sure. Of course, hot glue was quite useful."
