Choosing the Right Android Tablet

As mentioned earlier, the first version of Android that Google intended for tablet use is version 3.0, code-named Honeycomb. Honeycomb is designed around larger screen sizes and allows apps to do things like offer expandable menus. As an incentive for tablet makers to adopt Honeycomb, Google restricted access to the Android Market to phones only. (The UK version of the Galaxy Tab can make phone calls, which is likely how Samsung got around the restriction.) Google also later made exceptions for the Samsung Galaxy Player, which is a phone-sized media player, and the HTC Flyer, which is also known in the US as the EVO View 4G.

That doesn't mean there aren't a few tablets out there that run on previous versions of Android. The original Samsung Galaxy Tab, some Archos tablets, and the HTC Flyer are all tablets that run on Android 2.2 or earlier.

The problem is that these previous versions of Android require a lot of modification by the device manufacturers. Google won't certify all of them to use the Android Market, so some of them need an alternative app market. That cuts down on the number of available apps. Many also have modified user interfaces, and that may mean apps need to be customized, which further erodes the number of available apps.

Android is free and open-source, but Honeycomb has some hefty minimum hardware requirements. Many tablets that don't support Honeycomb may simply be incapable of the upgrade.

Modified Honeycomb

There are a few tablets that are capable of running Honeycomb, but will sport a modified user interface. This will likely include the HTC EVO 4G. It's not available at the time of writing, but HTC has announced that the device will upgrade from Gingerbread to run a version of Honeycomb modified to look more like HTC Sense phones. The Notion Ink Adam runs a modified version of Android called Eden. The Samsung Galaxy Tab 10.1 shipped with Honeycomb and offer an upgrade to a modified interface. The Kindle Fire uses a heavily modified interface that isn't recognizable as Android.

It's difficult to purchase an Android phone without some sort of modified interface, and device makers think it distinguishes their brand for consumers. The problem is that a modified interface also slows down upgrades and makes developers work harder to tweak apps for different versions of Android. The good news for now is that there are plenty of Android Honeycomb tablets that offer a “pure Google” experience, and Google is making it easier to write apps that handle different versions of Android.

Deciphering Screen Size

You'll likely see screen size listed in one of two ways: a single measurement in inches, such as “10 inches,” or a measure of pixel resolution, such as “1280 x 720.” It's important to understand both of these measurements and what they mean.

The first measurement of screen size in inches refers to the diagonal measurement of a screen. This is the same way TV and computer monitors are usually measured; and while it gives you an idea of the size, this measurement can seem misleading when you view two screens with identical diagonal measurements, but different aspect ratios.

Figure 1–1 illustrates how diagonal measurements can distort the true size of a screen. Most screens for phones measure between three and five inches, while most tablet screens measure between seven and twelve inches. Laptops measure between ten and seventeen inches, with ten inches considered “netbook” sized and seventeen inches considered pretty large.

Figure 1–1. Screen sizes are measured diagonally. One screen's aspect ratio is 4:3, and one is 16:9

Pixel Resolution

The other measure of screen size is the pixel resolution of the screen. You could have a twenty-inch screen on your tablet (that's huge), but it won't provide a great experience if it still has the resolution of a standard-definition TV.

Pixel resolution is the total number of pixels a screen displays, and usually that number is given as a simple measurement of the pixels in the width and height of a display, such as 640×480. The smaller your screen, the fewer pixels it needs to create a satisfying picture. However, even small screens benefit from higher resolution displays. Text is easier to read in eBooks, and movies and pictures look much sharper with those extra pixels.

Android doesn't assume all screens have the same size, aspect ratio, or resolution, so there's a lot of room for variety. Here are a few common standards to give you a point of reference:

• 320 × 240: This is a common smartphone resolution, called HVGA (for half VGA, though it's more correctly called QVGA for quarter VGA). You'll find this on many older or low-end Android smartphones.
• 640 × 480: This standard is known as VGA (Video Graphics Array), and it was originally a standard for computer monitors, though it's now considered very low quality. This size is close to the same size as standard definition TV broadcasts. (Technically TV video is 720 × 480 or 720 × 540, but the pixels on analog TVs were not square shaped like those on computer and tablet displays.)
• 800 × 480: WVGA (Wide VGA) is a common phone resolution that is giving way to qHD.
• 800 × 600: This is called SVGA for Super VGA. It's another computer standard that has gone out of fashion with higher resolution displays.
• 960 × 540: This is a standard for some displays because it's half the pixels in either direction of an HD display. It's a quarter of the resolution of HD because you'd have to put four of these displays together to have the same resolution as a 1080 HDTV display. For this reason, it's also known as qHD.
• 1280 × 720: This is one common standard for HDTVs. The other, higher standard is 1920 × 1080. In both cases, HDTV usually talks about the second number, 720 or 1080, when measuring resolution.
• 1024 × 786: This is a computer standard known as XGA for Extended Graphics Array.
• 1440 × 960: This is the widescreen version of XGA known as WXGA.
• 2560 × 2048: This is QSXGA for Quad Super Extended Graphics Array, and it's like the Cadillac of current standard computer screen resolutions. No tablets are shipping with anywhere near this resolution at the time of writing, although I'm sure some eventually will.