Those things are terribly outdated. A modern Nintendo DS with a homebrew card is much much better and powerful, and all the low level you want or more, with be

Those things are terribly outdated. A modern Nintendo DS with a homebrew card is much much better and powerful, and all the low level you want or more, with better documentation than Graphing calculators(made by open source contributors). If you don't care about low levelness any android smartphone have better capabilities. I have smartphones and tablets with Ubuntu, that is without a doubt the best system for learning if you are serious into programming today.