The cellphone and the personal computer are the two most formidable points of convergence in the digital world. The PC has devoured the typewriter, the TV, the telephone, musical instruments, darkrooms, video conferencing, and… Well the list just goes on.

But the cell phone has devoured the camera, the hi fi, the personal organizer, and, with the iPhone, it started devouring the PC in earnest. Right now, the only things an iPhone doesn’t replace a PC for are either because of obvious software limitations (e.g. no file system), intentional limitations (e.g. no dev tools allowed), physical IO limitations (small screen, crappy keyboard) or computing power (speed, capacity).

Given that any large screen can serve as the display of an iPhone, and any Bluetooth keyboard can serve as an input device, really the only thing preventing most of us from simply using our cell phones or cellular tablets as our only computers is a few years of Moore’s Law and better software, both of which are inevitable.

Apple is betting that iOS will be enough of an OS for the vast majority of users. Microsoft is betting that enough people will want a more “complete” PC OS to justify the baggage it’s including with Windows 8.

Yesterday, I visited an Apple Store (my reason is a pretty funny story in itself, but I won’t digress further) and saw about a dozen people, all with greying hair, being instructed on how to use their new iPads. The point here is that the iPad is still too much computer for many users.

I suspect that Google is on the right track with Chrome (the OS) and the wrong track with Android (Android is just too fiddly — which isn’t to say that it can’t be fixed or forked). Microsoft is on the wrong track with Windows 8, but if the Windows part is just a compatibility box that can be discarded later they can adapt as required.

Ultimately, the cellphone has all the advantages over the PC and will subsume it. It’s smaller, more portable, always connected, and everyone needs one anyway. The cellphone is the convergence device.

Typed on an iPad, by the way.