One of the simplifying assumptions that is built into this idea is that the input and output to the program are simple streams ( a file, a terminal ). Not surprisingly that makes things a lot less complex so you can focus on the programming.

Since a Raspberry Pi is only $35 or $50 with enough stuff to program it, that is one way to get started. Of course taking an older tossed of PC and installing Linux on it works too (which can often be done for free if there are businesses around)