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Domain 2.0: Laptops and Portable Devices - Other Portable Devices

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Tablet PCs
Personal Digital Assistants

Laptops certainly aren't the only portable devices on the market and they certainly aren't the smallest. There are a wide variety of portable options available today, many of them providing some of the functionality of a computer. For example, an iPod can store music, contacts, photos, etc., however, these types of devices will not be covered by the exam because they aren't full-fledged computing devices. In this section, we are going to cover the devices that are essentially mini computers.

Tablet PCs:
Tablet PCs come in 2 different form factors called Convertible and Slate (see right images). Slate varieties are flat and thin much like a tablet of paper. Convertible varieties can be configured just like a laptop or have the screen folded on top of the keyboard so that it resembles the slate variety. These devices have many of the same ports and slots that a laptop does. Many will have USB and/or firewire ports, PC Card or ExpressCard slots, and ethernet connection. Most tablet PCs have Bluetooth and WiFi capabilities as well. What you won't find on most of these devices is an internal optical drive.

You may be wondering how these devices function without a mouse and keyboard. Tablet PCs use a device called a digitizer which is usually located behind the LCD screen. This input device allows you to interact with the screen using a special pen called a stylus. There are a couple of different digitizer technologies available as follows:
  • Active Digitizer - In most current tablet PC's, an active digitizer is used. An active digitizer, used in most tablet PCs, can track the position of the pen when it is in proximity to the digitizer. This feature allows the user to "hover" over items on the screen. This can provide helpful functionality such as the ability to view tooltips and auto-hidden items, and to navigate through menus without accidentally activating an item. The advantage of using active digitizer is that only movement of the stylus affects the mouse pointer and ignores other contact like your hand on the screen.
  • Passive Digitizer - Passive digitizers are also known as touchscreens. This type only knows where the position of the finger is when the user presses down on it. This causes the pointer on the screen to jump to the location of the press and instantly "click". Passive digitizers are either capacitive or resistive. The capacitive touch screen panel is coated with a material that stores electrical charges. When the panel is touched, a small amount of charge is drawn from the point of contact (the finger). Circuits located at each corner of the panel measure the charge and send the information to the controller for processing. Capacitive touch screen panels must be touched with an unprotected finger. The resistive touchscreen panel is coated with a thin metallic electrically conductive and resistive layer that causes change in the electrical current which is registered as a touch event and sent to the controller for processing. The resistive touchscreen panel can be operated by fingertip, stylus, and does not need direct skin contact in order to operate. Both capacitive and resistive touchscreens offer lower accuracy and a higher rate of error such as the case when a user's hand rests on the screen surface. This makes them less common in tablet PCs.
Tablet PCs are fully functioning computers that can run an operating system such as Windows XP Tablet PC Edition. What makes this operating system very different is that it allows the user input data by either tapping keys on a virtual keyboard (on screen), or writing in a special window which is converted to text using character recognition software. Speech recognition is also being used with tablet PCs.

Tablet PCs offer another form of input called Digital Ink. Digital ink allows you to draw or write on the screen without the tablet trying to convert it to text or interpretting it as a click or double-click. This is useful if you want sketch a diagram or take some quick notes, for example.

Personal Digital Assistants:
Also known as PDAs, these devices are similar in some respects to tablet PCs, but are much smaller - most of them being handheld size. Input to a PDA is similar to that of a tablet PC. They use a stylus and a touchscreen that is similar to a passive digitizer in behavior. They also include a virtual keyboard, can use character recognition, or digital ink as input methods just like tablet PCs.

PDAs use memory sticks like a digital camera. The most commonly used types now are MiniSD and MicroSD which are smaller versions of the SD standard that are commonly used in cell phones.

PDAs run special operating systems which include Microsoft Windows CE, PalmOS, PocketPC, and some even run Linux. Most of these operating systems have the capability to sync with your computer. They either come with a cradle that is connected to the computer via a USB port (usually), or they sync via bluetooth. When you place the PDA in a cradle, it not only charges the device, but syncs the information with that on your computer. For example, let's say you met an old friend and added their contact information into the contacts on your PDA. When you place it in the cradle (or connect via bluetooth), that contact will be added to your contacts in Microsoft Outlook (for example). If you add a contact in Outlook, it will sync to your PDA as well.

Most PDAs have a built-in infrared port that is used for "beaming" which allows you to wirelessly transfer data from one PDA to another. For example, this would allow you to beam a picture from your PDA to a friend's. The limitation of this is that infrared has a limited range so you have to be pretty close to the other PDA (i.e. same room).

Many cell phones are now providing PDA-like features, many of which even provide email and web browsing through the cell phone network.