I don't like mechanics that are detached from the actions they're meant to represent. The more detached they are, the less I like them. I have yet, however, to find a sufficiently representational way to deal with computers. Modern games have this problem all the time. I don't like Shadowrun because I don't like their approach. I don't like giving the players some dice and saying "Check your programming skill," because anything that relies too much on simple skill rolls feels like a cop-out. I'm from the world of AD&D and before, where your character's skills were a supplemental set of things that generally gave you new binary abilities. It was rarely important to test whether or not you succeeded at cobbling, for instance. You merely said "I go make some shoes for x hours."
The question, then, is how to model computer use. Generally, it is done by aggregating a number of computer-related skills. "Computer use" itself covers generic usage. There's also sometimes "programming" as well as a few extra skills that govern the different aspects of using a computer. I've never noticed computer science as a skill in any system.
Being able to produce programs of your own is a powerful ability. There should be, one would think, a process of setting how difficult the program should be to create, checking a chart for the required time and debugging, and then the accumulation of successes with the skill check over time. Perhaps a period of five hours is the correct method, with one skill check accruable per hour. Each level of complexity of the program can then take 1d6 successes. So far, so good. This makes a ramping system whereby longer programs will, on average, take longer to create.
But that can't be all. We also need to know how programs work. What effects they have on the game. Are they simply tools, required to complete tasks? Are they something more? Bonuses to certain rolls?
These are questions I find myself asking, running a GURPS game set in the future. If there are answers, I'd be glad to hear 'em. Else I will look through the great archives of the internet and try my own computer use check.