Ah, the good ol' brain-frame computer. All the computing you need right at the tip of your neurons, always on, always ready to play a quick game of Doom at the drop of an eyelash. A mainstay of cyberpunk and certain other types of (extremely) speculative fiction.
With current technology this doesn't stand a chance of happening. There are so many problems with the idea that we've basically stopped trying. No, seriously. We have literally stopped trying to put computers in peoples' brains, because it turns out to be a really bad idea. (The Declaration of Helsinki probably has something to do with it too. Spoilsports.)
What we're doing these days is running wires to send data back and forth to implanted electrodes connected to various neurons. Mostly forth, since reading data from the brain turns out to be bloody hard to do. Most commonly this is used to allow deaf people to hear... kind of. Electrodes in the cochlea to stimulate the auditory nerve are attached to an induction pickup in the skull, which is fed data from an external hearing aid.
There are several good aspects to this kind of arrangement, not least of which is that the hearing aid (the external part) can be replaced almost instantly simply by swapping it out for a new unit. All of the internal elements are chemically inert, no internal power supply is needed and almost all of the heat generated by the system is in the external unit. Winning!
OK, so we also used brain electrodes to remote control cockroaches. For spying, of course. Can't you just imagine a little army of cockroaches with camera packs and tiny little microphones, all controlled by a room full of bored remote operators in Langley or something? (Kinda sounds familiar now that I think on it.)
Meanwhile, Elon Musk has decided that humans need to join with computers to bring about the singularity. So far they have a device that works in pigs and monkeys to read data from the motor cortex, so that's something. The eventual goal is to be able to put electrodes in a human brain so we can transfer data between that brain and a computer, merging humans with their technology.
The question "how can I stick a computer in my head" might not be the best one to ask. Perhaps "where can I stick a computer to talk to the electrodes in my brain" might be better. Wearable computers that you can take off when you shower perhaps? A computer in a belt-pack or a neck ring? Maybe. Or maybe we just go with Bluetooth. Everthing else seems to use it.