Understanding the workings of the iPad

The concept of tablet computers has been around for decades. In 1964, the Rand Corporation created the Grafacon, also known as the Rand Tablet. This $18,000 device featured two key parts: a screen and a drawing surface. The user would hold an electronic stylus and sketch on the surface, with the drawings appearing on the screen.

Even though Rand's innovative design didn't immediately disrupt the tech world, the keyboard and later, the keyboard-mouse combo, became the dominant interface for computers. That didn’t stop other companies from attempting to introduce tablet devices. While several options came to market, none made a significant impact with consumers — at least until January 27, 2010.

That day marked the unveiling of Apple's long-awaited iPad. As with most Apple products, its development was shrouded in secrecy. However, journalists, bloggers, and analysts had been speculating about the device for years — some even correctly predicted its name in advance.

At first glance, the iPad resembles a larger version of the iPhone or iPod touch, but with more power. It's bigger than these devices but still smaller than a traditional laptop. Its smooth design and innovative engineering are signature Apple. While some critics argued that it was simply a bigger iPod Touch, Apple once again revolutionized the market. With the iPad, Apple didn’t just improve upon the tablet — it created the entire tablet market, one focused on touch-based devices for streaming videos, browsing the internet, and reading digital books and emails.

Between its launch in early 2010 and the release of the fourth revision in late 2012, Apple sold over 100 million iPads [source: New York Times]. Priced at $500 or more, the iPad quickly proved to be a massive success. Since its debut, Apple has continued to refine the iPad, upgrading its hardware with faster internals and a higher resolution screen to stay ahead of the competition.

But hardware alone doesn't explain the iPad's popularity. To understand its success, we need to examine its features, such as its user-friendly interface and access to an extensive app store with thousands of downloadable applications.

iPad Design

Much like the iPhone, the iPad is designed primarily for touch interactions. Its front features a 9.7-inch (24.6-centimeter) touchscreen, with a single button beneath it — the same Home button as found on the iPhone. Apple offers the iPad in two colors: one with a black bezel and the other with a white bezel. The front also includes a webcam for FaceTime video calls, while the back has a higher-resolution camera for taking better photos. The iPad's design resembles that of the iPhone 3GS, with a sleek, curved metal body. A power button sits on the top edge of this curved surface, and the only other buttons are located on the right side: a volume rocker and a button for muting or locking the screen's rotation.

The fourth-generation iPad measures 9.5 inches (24.1 cm) in height, 7.3 inches (18.5 cm) in width, and 0.4 inches (1 cm) in depth. Unlike most Android tablets, Apple chose a 4:3 aspect ratio for the iPad rather than the widescreen 16:9 format. This square-like design ensures that the iPad is well-proportioned in both portrait and landscape orientations, though it sacrifices some screen space for widescreen videos. The iPad features an IPS (in-plane switching) LCD display, offering superior color and viewing angles compared to standard twisted nematic TFT displays found in many notebooks and monitors. For example, the iPad remains clearly visible from a viewing angle of 178 degrees [source: Brandrick].

Although the iPad's overall design hasn't drastically changed over the years, it has undergone changes in weight. Apple initially reduced the iPad's weight from 1.5 pounds (0.7 kg) to 1.3 pounds (0.6 kg) with the iPad 2. However, the third and fourth-generation models became slightly heavier due to the inclusion of a larger battery. While adding weight is unusual for Apple, the reason was clear: the third-generation iPad introduced a much higher resolution display, making content sharper and more detailed.

We'll explore the details further on the next page, which is dedicated to the iPad's hardware.

iPad Hardware

When disassembled, tablets and smartphones share many similarities with laptops. They all contain the same basic components: a processor, memory, screen, and battery. However, there are notable differences between mobile devices and full-size computers. While your desktop PC likely has a large, separate graphics card, mobile devices like the iPad utilize systems-on-chip (SoCs). A SoC combines the CPU and GPU into one compact unit, which is both energy-efficient and space-saving.

The fourth-generation iPad, released in late 2012, is powered by the Apple A6X, a 1.4GHz dual-core processor with a quad-core GPU. At the time of its launch, benchmarks showed it was the most powerful SoC available [source: Extreme Tech].

The fourth-generation iPad also features 1GB of RAM, a 720p FaceTime front-facing camera, a 5 megapixel rear camera, a 42.5 watt-hour battery, Bluetooth 4.0, a standard sensor package (gyroscope, accelerometer, and ambient light sensor), and a digital compass. Every iPad includes a WiFi chip, and Apple offers models with 3G and LTE cellular connectivity. The base model starts with 16GB of flash storage, but for an extra $100 or $200, you can upgrade to 32GB or 64GB.

With the iPad 2, Apple introduced a new cover called the iPad Smart Cover. It uses magnets to securely attach to the iPad, and it can be folded into a triangular shape to serve as a stand. When the cover is attached, the iPad automatically enters sleep mode, helping conserve battery life while also protecting the screen. The iPad Smart Cover is sold separately from the tablet itself.

The iPad's most remarkable feature is its display, particularly evident in the third and fourth-generation models. While the first two iPads featured a 1024 by 768 pixel display, the third-generation model upgraded this to an impressive 2048 by 1536 pixels. This resolution surpasses most computer monitors and HD TVs! Apple calls these high-resolution screens "Retina" displays because the pixel density is so high that individual pixels are virtually invisible.

Does that mean you'll be squinting to read on the iPad 3 or 4? Not at all. Although the display still presents content at the same resolution, it essentially uses four pixels to represent one image pixel. This increased pixel density reduces aliasing, resulting in smoother, sharper text and images. Apple kept the resolution the same to ensure that apps designed for earlier iPads would still function perfectly on the new display.

While the iPad's hardware is impressive, it's the iOS operating system that truly defines Apple's strength. Now, let's delve into the iPad's user interface and its app store.

iPad Software and Apps

If you're already familiar with the iPhone or iPod touch, you'll likely find the iPad intuitive to use right away. All three devices automatically rotate the display when you turn them, thanks to built-in three-axis accelerometers. Like the iPhone and iPod touch, the iPad features a full QWERTY on-screen keyboard. When used in landscape mode, the iPad's virtual keyboard is almost the same size as those on iMac systems.

The iPad comes preloaded with several essential apps, including the Safari browser, the Newsstand app for magazines and books, the iTunes store for music, and others like Mail, Photos, Clock, Calendar, Notes, Contacts, Messages, Camera, and Game Center. However, the App Store offers even more, with over 650,000 apps available, of which more than 225,000 are specifically designed for the iPad. iPhone apps are also compatible, though they won't take full advantage of the iPad's larger screen.

The App Store continues to expand with an ever-growing number of apps. iOS itself evolves over time, but its fundamental layout remains consistent: a grid of app icons that makes it easy to navigate. You can swipe left or right to access additional pages of icons, while the dock at the bottom remains fixed, offering quick access to your most-used apps.

Many of iOS's features have become standard for touchscreen devices. For instance, you can pinch to zoom in and out of photos or websites, long-press on apps to either delete them or rearrange their order, and drag icons on top of each other to create folders. Swiping down from the top reveals the Notification Center, which organizes alerts like new emails, text messages, missed calls, and more.

Games and various other apps take full advantage of the iPad's hardware in different ways: some are controlled by tilting and rotating the device, activating its motion sensors, while others use touch gestures like tapping and swiping. The third and fourth-generation iPads also come with Siri, Apple's voice assistant, which allows users to control different functions of the device through voice commands.

Now that we understand the basics of how the iPad works, let's explore some of its most popular uses. These are the reasons why over 100 million people have chosen to replace or supplement their laptops and smartphones with an iPad.

How to Use the iPad

Both Apple's iBooks and Amazon's Kindle app offer vast selections of books. Many users choose the iPad as their e-reader. Other services, such as Instapaper, are tailored for devices like the iPad. Instapaper lets you save web pages to read later, simplifying them into clean, text-only formats for easy reading.

Since 2010, tablets like the iPad have significantly influenced web design. More websites are now optimized for tablets and mobile devices, and the idea of separate mobile sites is gradually giving way to adaptive designs that work across a variety of screen sizes. This shift reflects the iPad’s strength: consuming content. While the app store offers thousands of apps, only a few focus on content creation. There are creative apps like drawing programs and Apple's GarageBand for music, but touchscreens still can't match the precision of mice and keyboards for detailed creative work.

With Apple releasing a new iPad every year, there's no shortage of options available, even though older models are phased out. Many previous models can still be found second-hand, and we'll outline the various versions of the iPad here.

Different iPad Models

All iPads come with WiFi, but Apple also offers versions with 3G and LTE connectivity. The cellular models are pricier, and you will need a data plan from a carrier to use the service. In the U.S., Apple teamed up with AT&T and Verizon to offer 3G data on the iPad 2. When the iPad 3 was introduced with the Retina display, it also gained 4G LTE support, with AT&T, Sprint, and Verizon carrying the device.

The WiFi-only iPads function similarly to notebooks or netbooks, connecting to the Internet via built-in WiFi. The limitations for WiFi models are the same as those for a laptop. The WiFi + 3G models offer more flexibility, allowing you to access the Internet and check emails using 3G, though it comes with extra costs. In this case, you'd pay a higher price for the 3G-enabled iPad and also purchase a data plan through AT&T or Verizon.

Since January 2010, Apple has released four versions of the iPad. The fourth generation model introduced a faster processor and swapped the 30-pin dock connector for a smaller Lightning port, which was first used in the iPhone 5 in 2012. Otherwise, it’s very similar to the third generation iPad, which introduced the Retina display and was marketed as "the new iPad." Both the original 2010 iPad and the iPad 3 have been discontinued, but the iPad 2 is still available. It's lighter, priced at $400, and features a smaller battery compared to the fourth generation iPad, which required a larger battery for its high-resolution screen.

Apple provides a detailed comparison of all its current iPad models on its website. Here are the key differences: The iPad 2 is more affordable and lighter than the iPad with Retina display, but it has a lower resolution screen, less powerful cameras, and an older processor. Additionally, it uses the 30-pin dock connector, and its cellular model lacks LTE support. The newer iPad, however, offers the same battery life, supports Siri, comes with the new Lightning connector, shoots 1080p video, and features a 720p front-facing camera. Most notably, its A6X processor incorporates a quad-core graphics chip, making it the most powerful mobile system-on-a-chip available by the end of 2012.