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(1)Lesson 3: Computer Hardware and Concepts Lesson Objectives
In this lesson, you will look at different types of computers, and learn some basic hardware terminology and concepts. On completion you should be familiar with:
different types of computers
internal computer components and their function input/output devices and their function
caring for computer hardware
Identifying Computers
Objective 12.2, 12.3
Computers can be found almost everywhere we look. Most people are familiar with the ones designed to be used as multipurpose computing devices, and these are the ones we will discuss in this lesson. You should be aware, however, that other types of computers can be found embedded in products such as automobile engines, medical or industrial equipment, household appliances, and calculators
Desktop Computers
Desktop computers are fairly large and are designed to sit on, beside, or under a desk. They can be found in homes, schools and businesses around the world
There are two general types of desktop computer: the PC or personal computer, based on a design originally introduced by IBM, and the Mac, designed by Apple. Several different companies manufacture PCs, while Apple alone manufactures Macs
Most PCs come with Windows preinstalled, while Macs come with Mac OS X. You can, however, install the operating system of your choice
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Even from the beginning (1984), Macs were designed with the monitor and processing unit in one case, which reduces the number of cables required, while PCs have required that you connect a separate, external monitor Today, allinone desktop units are available in both Mac and PC varieties
Blast from the Past: In 1981 IBM was the first company to sell personal computers to consumers. These machines were called “IBM PCs.” Other manufacturers began producing lessexpensive models based on the same design. These machines could run the same software as the IBM PC, and they were marketed as “PCcompatibles” or “PC clones.”
Desktop computers are stable and powerful and almost always include the ability to play rich multimedia (sound and video). They usually include a network port for a wired network connection, and many include builtin wireless networking ability as well. The primary disadvantage of a desktop system is that it is not portable because it must always be plugged in to an electrical outlet while you are using it. Additionally, you must attach a separate mouse and keyboard before you can use the system
Laptop or Notebook Computers
Laptop or notebook computers are designed to be portable. They are small and light enough to sit on your lap
They are also selfcontained; everything you need (display, keyboard, speakers, pointing device) is included in one unit
Laptops run the same operating systems as their desktop counterparts, and include the same internal components such as a hard drive and installed memory. Laptops also include a rechargeable battery that is charged from an AC adapter
Laptops are very popular with students and business people alike because of their portability. For example, students can bring a laptop to class and take notes, then take it home to do homework and other assignments Aside from their portability, laptops are popular because:
They are powerful enough to run most productivity and entertainment software. That is, they can run Office and play movies and stream audio, just as well as a desktop system. This makes them wellsuited for the needs of most users
They usually include builtin wireless networking capability They are available in PC and Mac models
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In some cases, the power consumption is considered a “greener” alternative to desktops
You can purchase a number of accessories to enhance your laptop computing experience and make it more like a desktop computing experience. For example, you can connect to a larger monitor, add an external full size keyboard with a number pad, or connect a mouse if you don’t like using the builtin touchpad
Disadvantages:
They generally are not as powerful as desktop systems; they come with less storage space, less memory and lowerpower graphics cards. This can make them poorly suited for running specialized software like graphics manipulation and videoediting programs that require extra computing or graphics power Laptops generally have a shorter lifespan than their desktop counterparts
Tablet PCs
A tablet PC (or simply, tablet) is a mobile computer small enough to hold in your hands. The computer circuitry, a battery, and a flat touch screen display are all rolled into a single handheld device. Tablets come with a microphone, speakers, and sensors that let the tablet “sense” which direction is up. All tablets have “touch screen” capability, enabling you to use your finger or a specialized pen called a stylus to touch an item on the screen to select it. You move your finger or stylus around the screen as you would a mouse, and you can “type” input using an onscreen virtual keyboard instead of using a physical keyboard
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Instead of hard drives, tablets use onboard flash memory for data storage and usually include a slot for removable storage devices, such as SD cards
Two types of operating systems are used in tablets – desktopbased and mobilebased
Tablets that run a desktopbased operating system are thicker and heavier than the other type. They require more cooling and they have a shorter battery life. However, they also have more connection ports and can run applications such as the Microsoft Office suite or Adobe Photoshop in addition to mobile apps
Tablets that run a mobilebased operating system are lighter, run cooler, and offer much longer battery life However, these tablets run only mobile apps. Mobilebased operating systems are also used on smart phones
Tablets are light, ultraportable, and wellsuited for entertainment and online activities. Most feature high resolution highdefinition screens and fast wireless networking capabilities. Many come Bluetoothenabled so that you can use external speakers without connecting them through a standard audio port. Popular models include the Apple iPad, Samsung Galaxy, or Windows Surface
On the downside, tablets are expensive and quite fragile. Because they do not include keyboards, they can be uncomfortable to use for long periods of time. Screens are smaller, which can lead to eye strain if you work on documents for extended periods of time, and in many cases it can be difficult to select text on a tablet
Some tablets include special connections that allow you to use them with detachable keyboards. In some models, the keyboard is part of a tablet case that doubles as a stand so that you can set up the tablet as a viewing screen to work on a document or to watch streaming media
2in1s
Tablets have become so popular that many laptops now offer tabletstyle features. These 2in1 “convertible” devices are laptops with special touchscreen displays that you can fold all the way back (360 degrees) so that you can use the laptop like a tablet
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Such devices offer the power, comfort, and documentediting capability of a laptop with the highdefinition, high speed streaming, touch screen capabilities of a tablet
Smart Phones
Smart phones are handheld devices that combine the features of a standard cell phone with those of a personal
computer. You can use them to make calls, send text messages, download music or electronic books from the web, take pictures or video, check your email, browse the Internet, access cloud storage, open and edit documents, use GPS navigation, make mobile payments and watch movies – all in the palm of your hand
Smart phones come complete with builtin system memory and support for memory cards for storing data, and include software for organizing appointments and contact lists, or for writing notes. Most models incorporate touch screen technology as well as the option to connect to a desktop or laptop computer and synchronize files (such as photos, music files or contact lists)
Smart phones use advanced mobile operating systems that allow for highspeed mobile data transfer, media streaming, and GPS functionality. Popular mobile operating systems found on modern smart phones include:
Android BlackBerry Firefox OS
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iOS
Windows Phone
To expand the capabilities of your smart phone, you can download and install mobile apps. Mobile apps are programs designed to run on mobile devices such as tablets and smartphones. Most smart phones are sold with several apps (web browser, email client, calendar and mapping programs, and a link to the default app store) preinstalled
To add apps, tap the link for the app store on the phone then search for, download and install the app(s) you want. Many apps are free, but some must be purchased
As cellular networks get larger and faster and smart phones get more powerful, the smart phone is growing rapidly in popularity and widespread use. The highend phones offer highdefinition screens, and lightning fast data transfer and media streaming. They are attractive, fun to use and are very handy for doing work “onthego.” However, they are expensive, and can be easy to misplace or break. Their screens are small and the small onscreen keyboards are not comfortable for extended use, such as creating a long document. Even though you can use productivity apps on them (for example, you can use an app that allows you to open and edit a Word document), these apps are not as powerful as installed versions of the software Servers In contrast to desktops, laptops, tablets and smart phones which are used for personal computing, servers are used to support other computers for business purposes A server is a computer that provides files or services to other systems on a network. For example, a server may provide email services, or host a web site, or store databases or documents for everyone in a school or business, or provide telecommunications or transaction services. A server runs an operating system designed specifically for use on a server. Examples of common server operating systems include Windows Server 2012, Mac OS X Server, or Linux Server
Servers also run special software for providing services. A web server may run Apache Web Server or IIS (Internet Information Server) for hosting and serving web pages; a database server may run Microsoft SQL Server; an email server may run Microsoft Exchange Server, and so on. These programs are very different from the enduser productivity software you may be used to using because servers are not used for personal computing
Systems marketed for use as servers are built differently than standard PCs; they are designed to be highly reliable and must have a low failure rate. Servers must be able to run continually, and are shut down or restarted only when software or hardware upgrades are being installed. They often include redundant power supplies, and because their main function is to communicate with other systems on a network, they are designed to transfer data quickly. In a server system, there is more focus on the processor power, memory and hard drive size than there is on features such as video and graphics capability. Because of their increased power, server systems are considerably more expensive than desktop systems
Supercomputers
Supercomputers are computers used for scientific and engineering applications that require a huge amount of processing power. Supercomputers have over one million processing cores, and generate so much heat they require complex cooling systems to keep them from melting
These machines easily cost $250 million or more, and they require a tremendous amount of power to run (between 7 and 9 million watts), bringing in an electricity bill of around $10 million a year
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Try It! Exercise
For each scene described below, select the most practical device to use from the options shown in the parentheses
Dan is in line at the airport waiting to go through Customs. He has 3 suitcases with him. Which device would he most likely use to check his email while is he standing in line? (desktop, laptop, smartphone)
Jannelle has to edit three large video files. Which device will she use? (server, desktop, tablet)
Marcie needs to make 127 ebooks available for download to students at her school. What will she use? (server, laptop, smart phone)
Ian and his sixyearold sister are waiting for their mom at the dentist’s office. Which device did Ian bring with him so that his sister could watch a movie? (server, desktop, tablet)
Looking Inside a Computer
Objective 11.1, 12.1
Personal computers are complete “systems” which include many components and attached devices. We use the term hardware to refer to all of these pieces you can actually see and touch; hardware performs the physical work of the computer. In contrast, software refers to the programs (applications and operating systems) you install and use in order to be productive. Software allows you to create spreadsheets or check email or manipulate images
Hardware can be divided into two basic types:
Internal components that are housed within the case
Peripheral devices that are attached to the computer through special connection locations called ports The case (or chassis) of the computer houses the power supply for the system and all the internal components These components (which include the microprocessor, memory chips and hard drive) are seated on or otherwise attached to a large printed circuit board called the motherboard or system board
The system board contains most of the computer's circuitry and provides pathways for communication among all the components and connected devices. It also provides ports for connecting external (peripheral) devices, such as a mouse, keyboard, speakers, and so on
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Together, the chassis and the internal components are called the system unit or box. The system unit for a desktop computer is fairly large and easy to open. There is usually enough “working room” inside to make it easy to install or replace components
Laptops and tablets include many of the same internal components as desktop systems, but because of the extremely tight working space, replacing failed components on a portable system is considerably more complicated than replacing them inside a desktop system. Repairs or component upgrades must usually be handled by professionals
About the Numbers
Before you can understand different types of hardware and how various devices compare to one another, you must understand how speed and storage capacity are measured
All the measurements revolve around the binary digit or bit. A bit is the smallest unit of data a computer can understand. A bit can have one of two values: a 0 or a 1. Bits are grouped in sequences of 0s and 1s to represent data
A group of eight bits is called a byte. The smallest unit of data humans can understand is represented by one alphanumeric character (‘a’ to ‘z’, or 0 to 9); an alphanumeric character requires a full byte of computer memory Because a byte represents such a small amount of data, these capacities are measured in thousands, millions, billions and trillions of bytes. Notice that a byte is indicated by a capital “B” in the abbreviation. The following table shows standard capacity measurements:
Measurement Abbreviation Equal to…
Bit A single binary digit Byte B Eight bits
Kilobyte KB 1,024 bytes (a thousand bytes) Megabyte MB 1,024 KB (a million bytes) Gigabyte GB 1,024 MB (a billion bytes) Terabyte TB 1,024 GB (a trillion bytes) Petabyte PB 1,024 TB (a quadrillion bytes)
Try It! Exercise
For each selection of two measurements, circle the one that is larger 932,000 bytes or 3 MB
4,000,000 KB or 2.8 GB 145,000 KB or 200 MB 8,000,000,000 bytes or 900 MB
3,020 MB or 2 GB
The Microprocessor / CPU
The microprocessor is a silicon chip and is often called the “brain” of the computer because it is where calculations and logical operations are performed. The microprocessor is also referred to as the Central Processing Unit (CPU) or simply as the processor
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The CPU controls everything that happens in the computer. All the hardware, all the memory and all the software send information to and receive commands from the CPU
Different CPUs process information and instructions at different speeds, and processor speed is measured in units called hertz. Silicon chips oscillate (or cycle) when electrical current passes through them. One hertz is equal to 1 cycle (or oscillation) per second. Because processor chips are very fast, this measurement is commonly used with the prefixes shown in the following table
Name Abbreviation Multiplies by Equal to
Hertz Hz 1 cycle per second Kilohertz KHz One thousand 1,000 cycles per second Megahertz MHz One million 1,000,000 cycles per second Gigahertz GHz One billion 1,000,000,000 cycles per second Terahertz THz One trillion 1,000,000,000,000 cycles per second
Most desktop systems available today include processors with speeds between 3 and 4 GHz. Most laptops include processors in the 2 GHz to 3 GHz range. When you purchase a computer, you will find the processor speed listed in the product description
Random Access Memory (RAM)
For a computer to process information, it must include a certain amount of installed system memory. This type of memory is also called Random Access Memory (RAM).
RAM is used for the temporary storage of information. Data and programs are read into memory from a storage location and then passed from memory to the CPU. Without RAM, a computer could not run programs or be used to create or edit files
RAM can store data only while the computer is on. Any information stored in RAM “vanishes” when the computer is turned off. When you close a program or save and close a file, the information is cleared from memory, and the memory becomes available to store other information
Understanding Storage Devices
Even though a computer loads software programs into RAM while you are working, the software is stored permanently on a storage device. Also, because data stored in RAM is lost when you turn off the computer, you must save your work to a storage device before exiting the software program or turning off the power
Commonlyused storage devices include hard disks, external drives, flash drives and memory cards
Hard Disk / Hard Drive
The term “hard disk” and “hard drive” are used to refer to a central storage location inside a computer. Hard disks are the primary storage location for both data and programs. Software programs must be installed on a hard disk before you can use them. The operating system must also be installed on a hard disk
Magnetic Hard Drives
Some computers use magnetic hard drives, which include moving parts. A magnetic hard drive stores data on platters, which are metal or plastic disks that are coated with magnetic material. A motor spins the platters around a spindle, while read/write heads (small recording/playback devices) hover close to the surface of the platters and read or write data to the magnetic coating
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Magnetic drives are usually found in desktop systems and some laptops Solid State Drives
Some computers use solid state drives, which do not have any moving parts. A solid state drive stores data on a set of interconnected flash memory chips that save the data even when the power is off
Flash memory chips can be installed directly on the system board, installed on a card that plugs into the system board, or housed inside a 2.5inch box that fits into the slot where you would otherwise install a magnetic hard disk drive
Solid state drives are smaller and more durable than magnetic drives, which makes them ideal for use in laptops However, they are finding their way in desktop systems as well
External Drives
External drives are hard drives contained in a case and attached to a computer with a cord as a peripheral device. External drives provide extra storage capacity for user documents, pictures, video, etc
You do not, however, install software on external drives
Flash Memory Storage in Tablets and Phones
Because flash memory chips (the technology used in solid state drives) can be installed directly on the system board, this type of storage is used in tablets and smartphones. Many tablets come with onboard storage memory, and most devices usually also include slots for SD cards to expand the storage capacity
USB Storage
A USB flash drive is a flash memory data storage device with a USB connector. These types of storage devices may also be referred to as jump or thumb drives. The drive consists of a small circuit board and a standard typeA USB connector, tucked inside a plastic or rubberized case. The connector may include a protective cap, or may retract into the case
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While the technology is basically the same, the flash memory chips used in a USB thumb drive are slower and less reliable than those used in solid state drives. That is the reason solid state drives cost more than thumb drives of the same capacity
Flash Memory Cards
You can use a flash memory card (also called an SD card) in the same way you would use a flash drive – to provide extra storage space. Flash memory cards are popular storage devices for digital cameras, cell phones, tablets, MP3 players, and GPS systems. The following figures show a few memory card formats
To use an SD card, insert it into the designated slot on your device