Can a hacker wrote his own programs?

Because I currently only own the Core Rulebook, and couldn’t find the answer in it, I am not sure, of it
In the moment I use basically the subreality rule of Mutant Chronicles:
Program restriction gives the difficulty, and cost the duration of the programming attempt.
Is this correct?

So far has I now, they are supposed to be acquired not created. But if a system fro mutant seems to work properly I don’t see why not. Check with your GM if you are a player.