Design by Chris Messina

One of the largest remaining questions about the Apple slate device (aka, the iTablet, Mac touch, or my favorite, the iPod maxi) is its operating system. Why? Because the iPhone's main selling point is the App Store and last I checked, apps listed in the App Store only run on the iPhone OS. So does this guarantee the Apple tablet will run jumbo-sized iPhone applications on a larger screen? I'm not so sure. Here are some potential scenarios:

It Runs iPhone OS With Scaled-Up Apps

If Apple were rushing to get this product to market then this could be a possibility: iPhone apps scaled-up to fit the larger screen resolution of a tablet. Everything would look the same except everything is bigger — perhaps exactly 2x as large with a 640x960 resolution screen.

Advantages:
If all UI elements are automatically scaled then nearly every currently available iPhone app would immediately be available on the new tablet.

Disadvantages:
This seems like a half-assed solution. A tablet's screen resolution is much larger than the iPhone and merely scaling existing apps is a cop-out. It doesn't use the advantages of a tablet-sized device so why pay extra for a tablet-sized device? Also, the normal way to interact with an iPhone is to hold it in one hand in portrait orientation. The normal way to interact with a tablet-sized device is to hold it in two hands in landscape orientation. Most iPhone applications are made to be used in portrait orientation so if they're scaled to tablet-sized proportions and not rotated then you'll have to hold the Apple tablet like a Kindle and not like a normal tablet to use any of the apps. This isn't optimal for a variety of reasons.

It Runs Customized iPhone OS With Multiple Running Apps

If the resolution of the tablet's screen is 960x480 then you could potentially run multiple iPhone apps at once, side by side, on the screen all at the same exact pixel dimensions for which they were designed.

Advantages:
Developers wouldn't have to rewrite their applications and users could finally run multiple applications at once.

Disadvantages:
This still doesn't let individual apps take advantage of the larger screen resolution — they'd still be locked into 320x480. Also, this would only really work if the apps were all using portrait orientation so they could be tiled side by side when holding the tablet horizontally. If an application was built to be used in landscape mode then it'd throw off the other applications on the screen and would look cluttered and messy.

It Runs Customized iPhone OS For Usage On Larger Screen, No Third Party Apps To Start

This seems like the most Apple-like solution to me. When the iPhone first launched there was no iPhone SDK, there were only Apple-created apps. Developers were clamoring for an SDK and by the time it was introduced there was a feeding frenzy — it was a gold rush.

The apps included on this tablet device would be a small assortment of Apple-created apps like Mail, Safari, iTunes, etc. These would all have redesigned user interfaces that would use the entire resolution of the new screen. Imagine iTunes LP format on a beautiful, new, widescreen display or Mail with multiple-panels just like its Mail.app big brother on the Mac.

Advantages:
Totally redesigned applications made for a larger screen open up a world of possibilities for user interaction and functionality. There's no doubt that the ones Apple redesigns (or, more accurately, re-develops) will be beautiful and will be a wonderful showcase and selling-point for the tablet.

Disadvantages:
If Apple's trying to keep the tablet a secret then there will be no publicly-available SDK at launch and therefore no third-party, tablet-centric redesigns of App Store gems when the tablet first goes on sale. This is a big disadvantage but it could be downplayed in a few ways: 1) large App Store developers (EA comes to mind) would gain early access to the SDK and could rewrite some key iPhone apps to be included in the "Tablet-Only" section of the App Store at launch or 2) Steve Jobs announces the tablet and sets a launch date a few months in the future, just enough time for serious iPhone developers to get an early, tablet-centric version of their app completed for launch.

It Runs Mac OS X

An unlikely scenario is that the tablet simply runs Mac OS X at a smaller resolution than normal.

Advantages:
Running full-blown Mac apps would be great in some ways, especially for the creative crowd. Developing for it wouldn't require any new SDKs and Snow Leopard already has multi-touch support built-in.

Disadvantages:
No App Store, no access to the current 85,000 apps is a gigantic negative. Other problems include the fact that a finger is a lot larger than a cursor and Mac OS X interface elements are designed for cursors so expect a lot of misplaced touches.

It Runs Some OS X & iPhone OS Hybrid

This would be the best of both worlds but it'd be very tricky to get exactly right. Do you launch iPhone apps from the Finder? Do you launch OS X apps from Springboard? Do iPhone apps run in little simulator rectangles? Do you use AppKit or UIKit to code interfaces?

Advantages:
The key advantage is that you'd still be able to access the full App Store catalog but also run full-blown Mac apps if needed.

Disadvantages:
Jack of all trades, master of none. If the tablet isn't 100% focused on a singular type of application user experience then there will be problems. Tiny buttons on Mac OS X apps would be frustrating to hit but then when running iPhone apps UI elements are correctly-sized — the dichotomy would be very annoying. The overlapping APIs would also be really tricky for developers to figure out.

Other Tricky User Experience Issues

The form-factor of a tablet is fascinating because it surfaces so many user interaction dilemmas that haven't been totally solved yet.

For example, the simple act of entering text via an on-screen keyboard. When holding the device in portrait orientation then the on-screen keyboard could be essentially the same as the iPhone's in concept, but what about when you're holding the tablet horizontally with two hands? How does the keyboard work in that scenario? If you stretch the keyboard across the device's screen when in landscape orientation then your thumbs won't be able to hit the middle keys without stretching and reaching. This orientation works on the iPhone because the screen is only 480 pixels wide but what happens when the horizontal dimension of the screen is 800px or 1200px? This same layout just doesn't work.

One idea is to split the keyboard and have the left side anchored to the left side of the device and the right side anchored on the opposite end with a large, open gap in the middle. It might look funky but now your thumbs can easily reach the middle keys since they're physically closer to where your hands are located.

Another issue is how you watch movies. The natural angle of the screen is to be flat whereas a traditional laptop's screen is angled up which increases visibility. How do you watch movies on a 7-10" tablet screen that has no keyboard? I know how much of a pain it is to watch movies on an iPhone since I usually do that when I fly — most times I end up holding it front of my face with one hand for an hour or so. I imagine that the tablet will come with some sort of stand — either built into the back like a picture frame or external like a small wedge — because otherwise users will have a hell of a time getting it at the correct viewing angle for prolonged interaction.

Fascinating Time To Be An Apple Fan

The build-up to the launch of the original iPhone was unprecedented. Years of rumors, tidbits, second- and third-hand accounts all culminated with the famous Steve Jobs unveiling of three magic devices that were actually one iPhone. I remember where I was when I first saw the magic text stream across MacRumors' live feed and how I felt, it really was magical. I think I'll have the same feeling when the Apple tablet is unveiled because it's Apple and I can't see them launching something that's not incredible. It won't just be a device to surf the web in the bathroom, it will be a new way to consume media that will revolutionize many industries.