“I recently bought Pi Zero - cheaepest single-board computer in the world, and I'm amazed how much it can do.
It is very small - smaller than most usb-hubs, so it's great for mobile/portable projects. I run RetroPie on it, and after hours of playing Pokemons (GBC) and Super Mario (snes) it only got a little warm. Unfortunately, pi zero isn't fast enough to run Nintendo64 games (which I believe is also true for psp/psx?). Compared to Raspberry Pi 2, there is no ethernet port, no usb, no hdmi - so I had to buy miniHDMI->HDMI adapter, USB OTG cable + usb hub (in the end still waay cheaper than Pi2B).”
