How many devices do you need?

In his most recent article, Paul Graham writes about what he calls “tablets” — his general term for iPhones, iPads, and the corresponding things running Android.  Like a lot of people, he thinks we’re headed towards a future where we only need, roughly, one device each: a multi-purpose phone/camera/computer/emailer/book-reader.

I’m not so sure.

I do agree that we’re headed to a place where the limits on what a device can do are imposed by its physical size — not because of how much compute-power you can fit into a small box (that constraint is pretty much gone now) but because of hardware-only components like screens, keyboards and camera optics.  The (not very exciting) insight that comes from this is that most of us are still going to need several different devices because we want different size/functionality trade-offs at different times.

At the top end of the big-and-functional scale, I can’t see myself ever not needing a laptop: something with a decent-sized screen that I can use for programming with multiple windows open at once, and with a full-sized keyboard for proper typing.  For a few years now we’ve been past the point where there is not much need for desktop computers except that they have bigger screens.  Already if I had to choose between my desktop and laptop, I’d unhestitatingly go for the laptop.  What, really, does a desktop box get you these days apart from a bigger screen?  Lower cost, I guess, is the only other advantage.

(Also at the top end is a Real Camera.  If you need better quality images than point-and-click devices give you — perhaps because you are preparing specimen photographs for publication — then you need a camera with proper optics, and there’s no way you can have that without it taking up physical space.)

At the bottom end of the big-and-functional scale, there’s my iPod Shuffle (1st generation).

It does almost nothing.

I think that is about the smallest a device can be: it has no hardware beyond a couple of buttons and a headphone socket. There’s no screen.  Although it doesn’t do much, that’s OK in some circumstances because its small size and nothing-to-go-wrongness mean that I will use it in situations where I wouldn’t use a laptop (on a bus, for example) or maybe even an iPod Nano (which I would hestitate to use on a beach for fear of sand damage).  The result is that the Shuffle goes with me almost everywhere, whereas I treat my laptop with kid gloves.

The question is, how many quanta of bigness-and-functionality are there between an iPod Nano and a MacBook?  (Sorry for the Applecentricity of these examples: those are just the devices I happen to have)  For most people there is at least one more point in between: their phones.  I’ve managed to make it to the end of 2010 without having a mobile phone — my position is that if people want to get in touch with me they know my email address — but we’re approaching the point where  phones do so many things that it’ll be worth having one even if I never tell anyone the number.

For a fair few people, it seems that something like the iPad fills another intermediate position; or maybe most iPad users have it instead of a laptop?  This interests me.  Could it be that most iPad owners don’t have a laptop?  Or, if they do, have they mostly stopped using it and shifted over to the iPad?  I don’t see this ever happening to me, but then I’ve never used (or indeed seen) an iPad, so I don’t know how seductive they can be.  I use the laptop mostly to make things (scientific papers, computer programs, blog entries, images) rather than to consume things other people have made; I get the impression that the iPad is really meant as a consumer device: a successor to the television rather than to the PC.  Is that fair?

So how many of the niches between small-and-powerless to big-and-powerful do your own gadgets fill?  Anyone have the whole Shuffle – Nano – iPhone – iPad – MacBook – iMac continuum?  (Or its non-Apple equivalent, of course.)  Does anyone have non-obsolete devices that they just don’t use because others get the job done?