I just traded a friend for this today but it is just the outer shell. Someone has stripped the electronics. Here is a picture of a similar one:

http://www.cyberroach.com/cyromag/six/mvc-877f.jpg

I was wondering what exactly this thing does? Mine has the on/off switch on the back, the A/B/C buttons on the front and two controller inputs and nothing else electronics-wise. From the picture above it looks like you plug in 24 cartridges and then plug it into an Atari 2600. I also found some info on the web including a title screen with different manufacturers listed and what seems to be an Imagic Selector cartridge. Is this something different? Is the hardware I am missing much different than the aftermarket cartridge selectors made for the 2600? Any info or website links would be very helpful.
Thanks, y-bot