1. Introduction to Computers
Mobile Devices

2. Mobile Devices
In the past 20 years, mobile devices have become more and more popular, and more complex. People are increasingly using their mobile devices as their primary computing device. As computer technicians, we’ll need to know how to identify, maintain and troubleshoot these devices
Tablets
Tablet devices use a touchscreen interface instead of the touchpad and keyboard used by notebook PCs
The touchscreen interface is usually capacitive, meaning that it requires conductive material, such as your finger tip, for input
Capacitive touchscreens provide multi-touch capabilities, which allow the tablet to recognize multiple finger touches at the same time

3. Smartphones and Phablets
Smartphones combine the functionality of a cellular phone with the features of a desktop computer
Smartphones can access the Internet either through a Wi-Fi connection or by using a 3G, 4G, and LTE cellular connection
They can also be used as a GPS navigation unit, a portable gaming device, and a mobile music player. Smartphones typically have a screen size between 2.5 inches and 5 inches
Phablets
Phablets are a hybrid between a smartphone and a tablet. They aren't as small as a smartphone and aren't as powerful as a tablet
Phablets usually have a screen size between 5.2 and 7 inches. In fact, any smartphone with a screen bigger than 5.2 inches is technically a phablet, not a smartphone
Most phablets are able to use special stylus pens to interact with the device. This allows for more accurate screen tapping for things like writing notes, drawing diagrams, or navigating apps

4. E-readers and Wearables
E-readers are similar in size to tablets, but they lack the functionality of a tablet. Their primary purpose is for reading digital books, newspapers, magazines, and other periodicals
Most e-readers use E ink to display digital content. E ink is a special technology that creates a high-contrast, black and white display
Even though they can only display grayscale, E ink screens are great for e-readers because they consume much less power than LCD screens and they don't suffer from visibility problems when used in bright sunlight
Wearable devices
Wearable devices are meant to be worn somewhere on the body. These devices range from fitness tracker wristbands and smart watches to smart glasses and virtual reality headsets
Most wearable devices are designed to interface with another device. A smartwatch by itself has a limited set of functionality; however, smartwatches are designed to connect to smartphones using Bluetooth. This unlocks additional functionality, such as reading texts or answering phones calls through the smartwatch

5. Mobile Operating Systems
There are three operating systems commonly used with mobile devices:
Android (open source)
The stock version of Android contains a home screen where you can put app shortcuts and widgets
The app drawer can be found using a button on the home screen
Customization possibilities are endless, Android can even be made to look like Windows or iOS
High-end Android phones are as responsive as other OSes
Devices made with specifications from Google tend to run the best, as is the case with the Nexus, Android One and Pixel series
Android has the most number of applications in its Google Play Store
Many manufacturers create Android devices like Samsung, Sony, HTC, LG, and Motorola

6. iOS and Windows iOS (closed source/vendor specific)
iOS is very similar in looks to Android
It has a home screen and a button to enter the App Drawer
iOS is light weight and has little performance lag. Since iOS software and hardware are built by Apple alone, it is well balanced
Be careful when updating to newer iOS versions on older phones, as they may run slowly, drain battery quickly or run hot, since the newer OS is designed to run on newer hardware
iOS devices or iPhones are solely designed and developed by Apple
Windows (closed source/vendor specific)
Apps on the home screen are tiles. Swiping the tile to the left gives a list of apps installed on the device
Customization options are limited to changing colors and resizing the tiles
The Windows store has the least number of applications on their store
Windows mobile is officially a dead OS, and will no longer be updated or fixed

7. Mobile Sensors (1) Accelerometer Global Positioning System (GPS)
An accelerometer detects the physical movements of the device by measuring its linear acceleration in one dimension
This is one sensor that is usually involved in deciding phone orientation, and can be used for gaming and other apps
Global Positioning System (GPS)
GPS is a space-based navigation system that provides location and time information in all weather conditions, anywhere on or near the Earth where there is a fairly unobstructed line of sight to four or more GPS satellites
Mobile devices use GPS chips in order to calculate the device's location information. This is helpful for things like navigation applications and device location services
Geotracking is the ability to identify a person's current, physical location by obtaining GPS data from their smartphones or other GPS-enabled devices

8. Mobile Sensors (2) Touchscreen interface Gyroscope
A touchscreen is an input device normally layered on the top of an electronic visual display of an information processing system
A user can give input or control the information processing system through simple or multi-touch gestures by touching the screen with a special stylus and/or one or more fingers
The touchscreen enables the user to interact directly with what is displayed, rather than using a mouse, touchpad, or any other intermediate device like a stylus
Gyroscope
A gyroscope measures the vertical and horizontal orientation of the device
The device can detect changes in vertical and horizontal acceleration and respond programmatically. For example, changes in vertical and horizontal acceleration detected by the gyroscope can be used as input for a gaming app
The accelerometer and gyroscope combined allow the user interface to be automatically rotated to portrait or landscape mode, depending on the orientation of the unit

9. Key Features of Mobile Devices
Apps
Applications must be written to run on mobile devices based on the operating system and system architecture. App distribution is provided online by platform:
Google -> Play Store, iOS -> AppStore, MS -> Windows Store
Architecture
Two computer architectures are generally used by mobile devices:
x86: The x86 architecture is compatible with standard x86 PC hardware and software, which allows the device to run operating systems such as Windows. Some newer versions of Android can also run on the x86 architecture
ARM: Some tablets, such as the iPad, use the ARM architecture. ARM is more power-efficient and less expensive to manufacture than x86. Android runs primarily on ARM
Emergency notification
An emergency notification system is a method of facilitating the one-way broadcast of messages to one or many groups of people, alerting them to a pending or existing emergency
Most mobile devices will have some form of emergency notification built-in

10. More Key Features Internal storage Launcher Mobile payment service
Internal storage is a hardware component located inside the device and used for storing data
Some devices use removable SSDs, others use on-board flash memory (such as the iPad), and some also have external USB ports for removable storage
Launcher
Launcher is the name given to the part of the GUI that lets users customize the home screen, launch mobile apps, make phone calls, and perform other tasks on Android devices
Mobile payment service
Mobile payment services operate under financial regulation. Instead of paying with cash, check, or credit cards, a consumer can use a mobile phone to pay for a wide range of services and digital or hard goods
Networking capabilities
Mobile devices implement networking to provide networking connectivity
Bluetooth is also commonly implemented for connecting peripherals in place of wired USB connections

11. Even More Key Features SDK Android application package (APK)
A software development kit (SDK) is a set of software development tools that allows the creation of applications for a certain software package or hardware platform
To create applications, you have to download a specific software development kit. For example, the development of an Android app requires an SDK with Java, for iOS apps an iOS SDK with Swift, and for MS Windows the .NET Framework SDK with .NET
Android application package (APK)
APK is the package file format used by the Android operating system for applications
Virtual assistant
A Virtual Assistant is a program that understands your conversation, replies to you, and carries out many daily tasks for you like sending mail, making a search, opening apps, reporting the news and weather, and more. You can initiate these tasks using your voice
Wi-Fi calling
Wi-Fi calling allows your Android or iPhone to place and receive phone calls and text messages over a Wi-Fi network. If you have a weak cellular signal but a solid Wi-Fi signal, your device will automatically switch over and route calls and texts using Wi-Fi

12. IMEI vs. IMSI IMEI vs. IMSI
IMEI stands for International Mobile Equipment Identity. It is a unique number given to every single mobile phone, typically found behind the battery
IMEI numbers of cellular phones connected to a GSM network are stored in the Equipment Identity Register database containing all valid mobile phone equipment. When a phone is reported stolen or is not type approved, the number is marked invalid
IMSI stands for International Mobile Subscriber Identity. This is a unique identifier that defines a subscriber in the wireless world, including the country and mobile network to which the subscriber belongs. The IMSI is one of the pieces of information stored on a SIM card

13. PRI Updates and Radio Firmware Updates
The Primary Rate Interface (PRI) is a telecommunications interface standard used on an Integrated Services Digital Network (ISDN) for carrying multiple voice and data transmissions between the network and a user
The PRI is a level of service assigned by the ISDN, sometimes referred to as an ISDN PRI. The PRI provides businesses with digital access to the PSTN (Phone network). While ISDN PRI is usually associated with only voice transmission, it is capable of transmitting data, video, and faxes as well
Radio firmware
Radio firmware controls basic low-level functions like network connectivity, Wi-Fi, and GPS. For several years, "radio" meant "baseband", and controled network connectivity aspects only, while Wi-Fi and GPS are governed by OS drivers, like any other devices. Baseband updates may improve or diminish battery performance, network signal strength, and roaming capability

14. PRL Updates PRL updates
The Preferred Roaming List (PRL) is a database residing in a wireless device that contains information used during the system selection and acquisition process
Without a PRL, the device may not be able to roam. In some cases, having a missing or corrupt PRL can lead to a customer not having service at all
On many networks, regularly updating the PRL is advised if the subscriber uses the device outside the home area frequently, particularly if they do so in multiple different areas. This allows the phone to choose the best roaming carriers, particularly "roaming partners" with whom the home carrier has a cost-saving roaming agreement, rather than using non-affiliated carriers
PRL files can also be used to identify home networks along with roaming partners, thus making the PRL an actual list that determines the total coverage of the subscriber, both home and roaming coverage

15. Mobile Accessories
Mobile accessories include any hardware or software that is not integral to the operation of a mobile phone as designed by the manufacturer
Headsets
Mobile headsets allow you to listen to music and answer phone calls. Mobile headsets come in both corded and cordless varieties using Bluetooth technology
Speakers
Speakers allowing you to listen to your mobile device without headphones. Portable speakers can be connected to your mobile device using Bluetooth or through the earphone jack
Gamepads
Gamepads make it easier to play certain mobile games, and usually connect through bluetooth, or the devices charging port
Credit card readers
A credit card reader allows you to accept credit and debit cards payments through your smartphone or tablet

16. More Mobile Accessories
Extra batteries/chargers
Cell phone chargers have gone through a diverse evolution that included cradles, plug-in cords and obscure connectors. However, more recent devices generally use micro-USB. (Apple devices still use proprietary cables.) External batteries can be included in the case
Protective covers
Protective covers or cases are designed to attach to, support, and hold a mobile device. Protective covers are meant to protect a mobile device from drops, shock, and water
Memory/MicroSD
Some smartphones feature SD card slots, usually the smaller MicroSD variant. These, in combination with a compatible SD card, can be used to transfer files from one device to another, or simply to increase the storage capacity of the phone