The iPhone is Apple's biggest business- over 5 billion dollars a quarter, and a bigger piece of their revenue then either iPods or Macs (though roughly you could consider each a 3rd). Now Apple has a 4th main business, one that could very well equal the other 3- the iPad. The iPad, if you don't know, is Apple's foray into the tablet or slate computing market. A tablet is essentially a laptop screen with the computer hidden inside and a touch screen interface. No keyboard.

Like the iPhone, but bigger. Microsoft launched tablet PCs a decade ago, but they largely failed outside of a few niche markets.

, team task software The reasons are many, but in my mind 1) the applications weren't there, 2) it stayed a PC, and carried that baggage with it, marring the new paradigm, 3) the technology wasn't really there for an effective form-factor and touch user interface, and 4) the market wasn't there in terms of both users and developers. The new iPad from Apple is a game changer specifically because it is not a Mac and borrows more closely from the iPhone. Many people are disappointed because they were looking for a Mac slate, and got an iPhone slate.

They should be delighted- their favourite vendors will support them in due course, and those applications will follow the paradigm of the iPhone- immersive task-centric computing that require no training. A paradigm enabled by mobile touch-screen interfaces and proven unbelievably effective by the iPhone. If you haven't seen them, go to YouTube and type "Baby Using iPhone". There are 18-month old babies that can use the iPhone.

I believe it.

My 2 year old daughter can use the iPhone. And my 4 year old. Neither reads. Considering that my all my kids use my iPhone, that leaves only one person in my family that doesn't use a computer- my Dad. I can give him my iPhone, however, and he immediately knows to use it.

I can't say the same of the computer he's had for 6 years.

His wife does all the computing at their house. Usability, as much as mobility, is the huge value of the iPad as it was with the iPhone. Not traditional applications in a slate format, but built-from-the-ground-up slate applications for specific functions. And, in addition to filling a huge usability need, these applications will fill a market need- mobile computer applications at scale bigger then a phone, and more mobile then a laptop, which, currently, is served by netbooks.

The netbook attempts to fill this market for mobility- and hence the explosion of that market- but it doesn't do it well. As Steve Jobs put it in his iPad keynote, the netbook does all of it's jobs worse then a smartphone and a laptop. But it does attempt to fill the mobile need.

And that's why it is doing well (and why I bought one) in addition to low cost. But it's failure for most of it's tasks.

If I'm on the road, 75% of what I might use a netbook for, I do on my iPhone (email, looking up book reviews, finding movie times). The other 25%, is fairly limited- a seated, open area where I can open it an work on it. I never open a netbook on the subway, or to look up a phone number. I never open a netbook when I am standing. I never open a netbook where I don't have wifi.

I use my netbook for 1) writing, 2) web browsing, 3) reading eBooks, 4) watching movies. The netbook is a special purpose device. Outside of that, it's a tradeoff- cost for functionality. For what I use it for, the iPad is better, by far, except for the writing. And bluetooth keyboards fix that easily.

Think about it- you carry a iPad and a small bluetooth keyboard. 9 times out of 10 you don't need the keyboard.

Occasionally, you pull it out. That works for me, and as a convenience, not a disadvantage. So we use the netbook for limited functions, and as such, it's easily replaceable by another platform- even one with limited apps.

This tells use the market is there for the iPad, though it may be over-priced for the current majority netbook market. Of course, you could have said that about the iPhone as well. But as mentioned in our intro, there is even a more important aspect of the iPad that is transformational and magical (Apple's favourite word in the launch was magical), and that's it being baby and grandparent friendly. The task-centric touch user interface paradigm that has been so incredibly successful on the iPhone.

This is one area where PC tablets didn't succeed, and why the iPad will be successful (followed in short order by Google and HTC)- the usability of the device.

However, usability is theoretical until applications are developed. And you could argue that developers could have developed these great apps for the tablet PCs as well. However, they didn't, with a few exceptions- one being OneNote by Microsoft. The iPad is different because of the path blazed by the iPhone. Developers know how to build the right apps.

Online project management app, the UI paradigm is widely realized and understood now.

And, there is a large marketplace of developers who know they can sell their apps through the app store. The other big difference is the advancement of technology. You could easily argue that the iPhone wasn't even possible three years before it's launch, and the iPad wouldn't have been possible three years ago. So the iPad, by not being a Mac, is forcing the paradigm.

Rather then shoddy retrofits of applications built for an older, hard-to-user paradigm (the personal computer), apps will be slate applications rather then applications on a slate. The UI. It morphs to become the task at hand.

By being so immersively task-centric, it becomes so incredibly human-centric. The App Store.

It made applications accessible. I tried for about an hour in 2003 to install an application on my Blackberry. I failed. Wrong OS most of the time. That was if I managed to find apps.

I installed lots of apps on my Palm Pilot. Never updated any of them. And most of them were pretty poor. But for most apps, the task itself provides rich information that is best suited to a touch interface built specifically to that task. Earlier PDAs allowed for some of this, but failed for three reasons.

1. the interface technology wasn't there- touch, speed, resolution.

My guitar tuning app shows the same strings as my guitar. 2. the delivery platform wasn't there- the app store.

3. the ecosystem wasn't there- the size of the installed base and the developers for the applications. I call the iPhone task-centric computing. Some would call it human-centric, but I think it is human-centric specifically because it is so immersively task-centric.

We've seen videos of 18 month old babies using the iPhone unaided.

They new how to turn it on, go to pictures, and swipe through the pictures. Everyone I've handed my iPhone to could us it- instantly. Every app I've installed, I've been able to use- instantly. The iPhone is a task-immersive user interface paradigm. There is no data.

No file system.

Just applications geared specifically to certain tasks. The iPad is following the same path, but in a form factor that addresses another class of applications. Web browsing, email, art, video, books, note taking, art, music, and so on. Without the iPhone proving the paradigm and building the development community, and without the netbook market proving the lightweight mobile computing need, the iPad may have been a few years away, or launched and languished in niche markets until it slowly grew into the mainstream.

But it's timing is perfect and the market supports for it are there, both in the user and the developer community. In a way, both the iPhone and the iPad are very similar to the usability of the web. By providing only a UI to users, and no other background services for files and application management, the human-computer interaction was pushed up another level of focus and simplicity.

And you can see that in the popularity of web apps with novice users over traditional computer apps. In fact, most computer users now spend the vast majority of their time in the web browser.

It's amazing what removing menu bars and file systems do for application usability. Six months from now, if I were buying a computer for my Dad, or any other lightweight computer user, I'd probably get them a iPad rather then a netbook. And I think we will see a lot of that in the market- especially when the HTC GooglePad hits the market and provides slates are netbook level prices. As for myself, I don't need an iPad- I spend 14 hours a day in front of my computer. And when I'm not, I use my iPhone for email, weather, quick browsing, tuning my guitar, and soon, painting.

But, that's not entirely true. I want a good eBook reader, and I want mobile computing better then my netbook. Those were the main reasons for my netbook in the first place. So I may get one if I can justify the price and have enough usage. Of course, I have a professional interest as software developer, and have good reason there as well (if you suspect purchase rationalization is starting to happen here, you are entirely correct- in fact, it may be the entire motivation behind this article).

Also, I could then safely leave my laptop at home for those more casual outings- you know what I'm talking about, where you are the only one who brought a laptop and you never take it out. What?

That only happens to me? On a similar note, have you ever noticed how awkward and weird it is to show someone something on a laptop in a non-work environment? They try to watch without taking the laptop from you, and your arms slowly tire holding it the air until the item is done?

Have you seen the same with the iPhone? Someone starts a video and passes the iPhone over. Very different. Now consider the iPad.

Can you see the changing social interaction?

Another example. You are visiting friends for dinner. They ask about your project at work. Did you bring your laptop? No.

Your iPhone?

Yes, but it's too small to show well. Your iPad? Yes. And its perfect to bring out quickly and show a website, some pictures or a slide deck.

I love my iPhone, but it's not great for showing photos to family. It's a bit small. The iPad would be amazing.

There are a lot of interesting social computing benefits to the iPad that I think we will only appreciate once we've experienced them. Continuing that thought, one of the great things about new paradigms is the unexpected.

The iPhone has illustrated some amazing unexpected momentum in a few areas because of it's human-centric nature. Computer art is now considered real art, with exhibits of digital art starting to occur in the mainstream. And I'm inspired by this. I don't have much time to paint, but, by using the iPhone, I am much closer to painting then using my computer, and I a scratching this itch. The iPad would be a brilliant extension of this.

By introducing a new form factor on top of it's proven immersive task-centric human-friendly interface technology, we will see an explosion of applications that change the way we use computers. The one computer per child concept will become a one slate per child. We will buy our parents and grandparents slates instead of computers. A baby will sneak time on their parents slates, and surprise everyone by being fully fluent in mandarin by age 3. A mad child genius will get the self-serve education he needs to take over the world, and we will all become his slaves.

The possibilities are endless!