Not PC, again.
He, he, it goes back further than that, if you just mean handheld computers. Funny how the PC crowd got stuck on the notion that the world revolves around PC compatibility, and before that was pre history. The PC struggled as an fledgling sales success for years, for what was basically an heap or rubbish. They then made better rubbish, and so on, till today, where it is so complex most people don't realise ti is rubbish, though an much better sort. Linux people, the bane of an free and democratic society, behind over PC people, continue to hog the alternative better stream by making people think that Linux on PC is the way to go. In the early years of PC, and their blindly obedient IBuM'er Micro Sift slavers, it was plagued by the availability of other better computers, even an Sinclair QL ;) owned by people with brains .
Having said all that, by the 90's the tide was turning, and an problem with many of these new pocket PC type devices, was expense, and often low battery life. If they could have sold an personal version for $200 (even with Z-80 CPM/6502/ARM/68000 Mac OS) with game controls, TV/Monitor dock and IR wireless game controllers to play it on TV as an video game console, when not being carried around, imagine how many sales they could have made. Pity companies didn't figure this out, and the things were largely not an great success.
How long till an UMPC gaming handheld? The industry can't, largely, even do gaming: phones, media players and PDA's, so far. Even if they did, would they do it so badly, that PSP/DS would still outsell them.