Computer rules - do you have them?

[StagnantRabbit]

I think what I mean is do you have rules or time limits for your kids using eg laptop or ds? If so what are the rules, how do you use them?
DS7 had a Nintendo ds for Xmas. Hasnt been going mad for it but certainly playing every day. The computer is actually more popular.
What kind of time frame is realistic for playing on these items?
Thanks

Rules: I copied the ICT policy from their school, laminated it and stuck it on the wall.

Time limits: curfew externally implemented by Windows and wi-fi software (9pm for 13 y old, 8pm for 11 y old, 7pm for 9 y olds). Two computers between four children means that we have to have a timetable, which means that each child has enough computer time for their homework plus some free time.

I don't work with time tables.
There's a computer in the living room. The children can use that. If someone is on it you either got to share (go together behind the computer) or ask the one behind the computer when he's finished.

That's how it works over here.