An ultra-mobile PC (ultra-mobile personal computer or UMPC) was a small form factor version of a pen computer, a class of laptop whose specifications were launched by Microsoft and Intel in spring 2006. Sony had already made a first attempt in this direction in 2004 with its Vaio U series, which was however only sold in Asia. UMPCs are smaller than subnotebooks, have a TFT display measuring (diagonally) about 12.7 to 17.8 cm (5 to 7 inch screen), are operated like tablet PCs using a touchscreen or a stylus, and can also have a physical keyboard. There is no clear boundary between subnotebooks and ultra-mobile PCs.