Tablet sales will soon overtake PC sales. It doesn’t matter. Physical boundaries between devices are blurring to the point where a continuum stretches from smartphones through tablets to laptops.

The big disconnect isn’t tablets versus PCs, but mobile versus fixed.  

At Gigaom, Kevin Tofel reports Nearly 1 in 4 computers sold last quarter were tablets. Raw numbers show 28 million tablets sold in the last quarter compared with 88 million PCs.

Tablet sales are up 50 percent when compared to the same quarter last year. PC sales are down 8.6 percent. If those numbers carry on in a straight line – they won’t but bear with me here – then tablet sales will go past PC sales by early 2015.

That’s dramatic considering modern tablet sales began in 2010 with the first iPad.

It gets confusing when you look at the most recent devices to hit the streets. Apple’s iPad mini sits somewhere between a full-sized iPad and a large screen smartphone. As you go from small smartphones through to tablets, there are touchscreen mobile computing devices at every step from three inches to 10 inches.

Microsoft’s Surface may be a touchscreen tablet, but add the optional keyboard case, and physically it is close to an Ultrabook. Samsung sells a tablet that is essentially an Ultrabook with a detectable screen.

The only noticeable discontinuity in the device spectrum is moving from a large screen laptop to an all-in-one desktop. And given the lightness of today’s all-in-one’s even that step is no longer a huge leap.

Phones, tablets, PCs are not three markets. They are one market with a device spectrum.