I've got the power - digital power

The issue of supplying power that I mentioned in iMac or iTablet is an interesting one. Many people are getting used to the idea of USB devices that require no external power connection. To call these devices "self-powered" is incorrect because they are anything but, the correct term is "bus-powered" because they draw their power from the USB bus itself. Without the USB connection they are quite literally powerless.

To me drawing power from a single DC bus is a good idea, for home appliances that bus is the mains AC power connection - a bus that is dedicated to providing power. Mains is AC to facilitate easy conversion to a variety of voltages and to deliver a lot of power with the minimum of energy loss in the power delivery lines. However digital components have standardized on a variety of low DV voltage power inputs (+-5V,+-12V) and except for the CPU and graphics card are for the most part low power consumers. Furthermore modern switch mode power supplies make transformerless conversion of power inputs to various output values childs play. It makes sense to have a single power bus and discrete power supplies blocks that have all the digital power outputs available.

Instead of a plethora of 1.5V, 3V, 6V, 9V, 12V and more unregulated power bricks with transformers (aka "wall warts") hogging our power strips, why not just simple DC based power strips? Indeed why not make a smart power bus where the device can tell the power strip what it wants in the way of voltage and current and a smart power strip (aka power bus controller) that can tell the device "Yes, power is available" or "No, insufficient power available". The latter saves an after the fact failure of all connected devices due to blowing a fuse or tripping a switch, and allows a device that is underpowered to fail gracefully e.g. a sound system that can say "sorry, that's as loud as the volume can go with current power input". It also allows the power hub to negotiate power requirements and power down idle devices, eg. asking your computer, at the behest of the power company, if it can reduce its power requirements by 50%. The computer could do this by powering off the screen and the hard-drive and the graphics card and go into sleep mode. If the system is needed again the power hub could give the power company a few seconds notice of an impending increase in power demand which might be very useful to help the routing of residential and commercial power to the right places at the right time.

There's really no reason why any of these things can't be done. Even communicating back to the power company can easily be done with standard AC powerline transmission technologies. I just hope that future bus designers will cotton on to the whole issue of delivering power on the I/O bus. If they give it and its associated problems the investment in innovation it needs it will go a long way to removing this last "analog" anomaly of digital systems.