Processors

All these input and output devices have to be connected to some sort of computer. With competing products in the virtual reality world, this is done by hooking up the device to some sort of an external computer. This could be a mobile phone, desktop, or laptop computer. Of course, with that last option, you lose the possibility of walking around, so the engineers at Microsoft have not gone down that route. Instead, they put all computing parts inside the device. You will find a complete Windows 10 computer and a special piece of hardware that Microsoft calls the Holographic Processing Unit, or HPU in short, inside the device. So, the computer consists of a CPU, a GPU, and an HPU, making it quite powerful.

The HPU is there for a reason--the computer itself is not that powerful. The machine basically is a 32-bit machine with 2GB of memory (the HPU has 1GB of its own), so the computing power is somewhat limited. If the CPU or the GPU would also have to do the processing of all the raw camera data it receives, it would be too slow to be practical. Having a more powerful general-purpose CPU will help of course, but that would mean the batteries will have to be bigger as well. Next, there would be a problem with heat--a faster computer generates more heat. At some point, it will need active cooling instead of the passive cooling the HoloLens currently has. By having a dedicated processing unit that decodes all the data before passing the results on to the rest of the device, Microsoft is able to have a relatively lightweight, but still fast machine, an impressive piece of engineering, if you ask me.

The power for all of this comes from three nonreplaceable batteries, located at the back of the device. The reason that they are in the back is so that they can act as a counter weight to all the hardware in front, thus delivering a nicely balanced device that is comfortable to wear. The batteries are good for 2-3 hours of usage, depending on the applications you run on it. Recharging is done by plugging a micro-USB cable attached into a power source in it, and takes about 4 hours to complete.