Dunno, it all depends on what you already know or not. In the late 80's I've spend ages on small little crappy basic programs. Little of them did something that made sense, from today's perspective. But I guess that's the way things work: small steps, no rushing.
Do you understand all the program flow commands? (for-next, select, if-then, functions, local&global variables, arrays, banks, timers, etc. etc.)
Do you understand all the program flow commands? (for-next, select, if-then, functions, local&global variables, arrays, banks, timers, etc. etc.)