Listed here are portable game systems. As per the rules a portable is classified as such if it meets the following criteria:
It has it's own screen capable of displaying graphics
It has some form of interchanable media (carts, CDs, flash ROM, etc.)
It's primary function is to play games (thus no PDAs, calculators, etc.)
Some of these systems are handheld famiclones or clones of other game machines but are listed here as they meet the above description.