The System Unit

The system unit is the main component of the PC to which other components are connected. The system unit contains:

• Motherboard
• Microprocessor or Central Processing Unit (CPU)
• Memory (RAM and ROM)
• Power supply unit
• Disk drives

The Motherboard

The motherboard holds the microprocessor, memory chips (RAM and ROM), expansion slots, power connectors and any other microchips required for the PC to function. It is the actual heart of the PC as it determines the computational power of the computer. The main components of a motherboard are the following:

Photo of a typical motherboard

The Microprocessor
The microprocessor can be referred to as the brain of the PC. The microprocessor is also known as the CPU (Central Processing Unit). The microprocessor does the following:

• Carries out commands to make the hardware components perform actions.
• Processes data. This involves:
• Performing logical instructions such as comparing
• Performing mathematical instructions such as adding and subtracting

Although the instructions performed by the CPU are relatively simple, the CPU can execute many millions of instructions every second. This is what makes the PC such a powerful tool.

Memory (RAM and ROM)

RAM
RAM is used in many parts of the PC. It can be used to provide motherboard, video card, sound card and cache memory. System RAM is a form of high-speed memory; the microprocessor uses system RAM for the temporary storage of programs and data. Unlike disk drives, any information within RAM will be lost when a PC is reset or powered off. This type of RAM can be considered as the working space of the microprocessor.
RAM is measured in megabytes (MB). New PCs are generally shipped with no less than 64MB of RAM; however, many can be fitted with up to 512MB.
Speed of RAM is measured in nano-seconds (Ns): the lower the figure, the faster the memory access time.

ROM
ROM is a special type of memory holding information that has been programmed into it during construction. The PC user cannot change this information.
An example of ROM memory is the PC’s ROM BIOS (Basic Input/ Output System) chip. This ROM chip contains a set of instructions that the microprocessor uses when the PC is turned on or reset. For example, it contains the code that allows the microprocessor to communicate with the floppy disk drive and hard disk drive so that the operating system can be loaded.

Power Supply
The power supply is responsible for converting the incoming electricity supply to the 5v and 12v DC power that is required by the PC for it’s operation. The 5v supply is used to power the circuit boards on the PC. The 12v supply is used to power motor-driven devices such as hard drives or CD-ROMs. Many newer systems also require 3.3v or 2.8v, as current processors tend to use lower voltages. Devices such as CD-ROMs and floppy drives are connected to the power supply using molex or mini molex connectors. The motherboard connectors are known as P8 and P9.

Disk Drives
If data held in RAM is to be kept permanently, it should be saved to a disk drive. Disk drives are the storage area of a PC. A disk drive can be divided into logical areas called directories (or folders). These directories are used to hold the files that contain your data.
The data is recorded as magnetic fields on the surface of the disk. These fields are written in concentric circles (known as tracks) as the disk turns. These tracks are divided into equal-sized blocks called sectors. Each track and sector has a number that is used to remember where each piece of data is.

The 3½” Floppy Disk
The floppy disk represent one of the most common data storage devices. Each side of a high-density 3½” disk is divided into 80 concentric tracks, with each track divided into 18 equal sectors. Each sector is used to store 512 bytes, or 0.5KB of information. Data is transferred from the disk into the PC’s memory (or from memory to disk) one sector at a time. The total capacity of this disk is, therefore:
80 tracks x 18 sectors x 0.5 kilobytes x 2 sides = 1,440KB or 1.44MB.
The 3½” floppy disk drive is often described as a 1.44MB drive.
Floppy disks do not have a sealed covering like a hard disk (see below) and are not as strong. They must be treated carefully, which means keeping them away from dust, magnetic fields and high temperatures. The main advantage of floppy disks is that they are portable and can be used for transferring data between PCs, and for storage of data away from the PC itself.

Hard Disk Drives
Hard disks are the main storage devices of PCs and have high storing capacities of several Gigabytes (Gb) of data. Most new PCs are supplied with drives in excess of 10 gigabytes (GB), and disks are currently available with capacities in excess of 70GB. This high capacity is achieved in two ways:

• Data can be packed more tightly onto the disk
• A number of disks can be mounted together onto a single spindle A hard disk is made of glass or metal as opposed to the flexible plastic from which floppy disks are made, and is mounted in a sealed unit, usually fixed inside the system unit. Hard disks are also known as fixed disk drives.
   Hard disks are considerably quicker than floppy disk drives as they rotate much faster and the data is more densely packed. This allows much quicker access to data than a floppy disk. When there is no disk activity for a few seconds, the motor on a disk drive can be automatically switched off to prevent excess wear on the disk drive. The disk is sealed in a dust-free casing to protect the magnetic surfaces.
  The considerable quantities of data now held on modern hard disk drives, means that a disk failure can be disastrous. It is therefore imperative that any files on a hard disk are backed up systematically and regularly.
  
  A PC may be configured with one or two floppy disk drives and one or more hard disk drives. The most common configuration for a PC is one 3½” floppy disk drive and one hard disk drive.

Do not confuse RAM with disk drives. Disk drives are used to store programs and data permanently and they have slower read/write times than RAM has.

Monitors
There is a wide choice of monitors available for the PC, varying both in screen size and technology. In general, monitors range in size from 14″ to 21″ and use Cathode Ray Tube (CRT) or Liquid Crystal Display (LCD) technology. The most important factor in selecting a monitor is to ensure it is compatible with the display adapter and that it will support its maximum resolution. Other points to examine are the dot pitch and refresh rate of the screen. A smaller dot pitch gives greater clarity. Monitors with refresh rates lower than 75Hz may flicker causing headaches and eyestrain.

Keyboard
The keyboard is the main input device of the PC. It is used for giving commands to the PC or typing documents. Although a computer keyboard is based on the old typewriter layout, there are some major differences in the ways that keys are used. Computer keyboards also have additional keys. Learning to use the unique keys and special functions of the computer keyboard can save you time and make you more comfortable with your computer. The keyboard is like a typewriter but with special keys. You use these keys of combinations of them for special functions. Below you can find some of the most common ‘special’ commands of a keyboard:

Mouse

There are many, many things for the novice to learn so that they are able to navigate Windows. The first thing that you should learn to do is how to use the mouse to navigate Windows. The mouse is another equally important input device, like the keyboard, very simple to use. It is extremely useful for navigation in software environments and can save much time and effort comparing to the keyboard for similar use. Your mouse gives you the ability to point to, select, and move items on the computer screen.

Modem

A modem is a device that translates the digital signals from your computer into analog signals that can travel over a standard phone line. A modem on the other end of the line can understand it and converts the sounds back into digital information. It is the device that will connect you to the internet or allow you to communicate with a friend. Modems come in different speeds and are measured in bps or bits per second.  A 28.8 Kbps modem transmits data at speeds up to 28,800 bits per second. A 56 Kbps modem is twice as fast, sending and receiving data at a rate of up to 56,000 bits per second. Most modems today are 56 Kbps. In case modems come with your PC as external devices they look like the device above. The other alternative is to have the modem mounted on the motherboard so it appears as internal device of the computer.

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Repeating Events Daily

Create a new event or select an existing event to edit. Check the “Repeat” box to display a pop-up window with additional options. Set the “Repeats” option to “Daily.” With the default settings, your event will appear on every calendar day in the future. Optionally, you can change the “Repeats Every” setting to have the event skip a chosen number of days, or set the event to stop repeating on a certain date or after a selected number of occurrences.

Google Calendar includes two tools to help you keep your daily schedule. If you want to set an event to appear in your schedule every day, you can create it once and set it to repeat, rather than make a new item for every day of the calendar. You can also turn on a notification setting to have Google Calendar send you a daily agenda, which contains your schedule for the day.

Receiving Daily Agendas

To set Google Calendar to notify you about your schedule every day, click the drop-down arrow by the calendar you want to use and pick “Reminders and Notifications.” Check the “Daily Agenda” box and click “Save.” Google will email you your schedule every day at 5 AM, according to your account’s time zone. Unlike other notification options, you can’t receive daily agendas by text message.

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By Danielle Fernandez

How to crop on an iPhone, Your iPhone offers a slew of photo editing tools that allow you to crop, refocus and otherwise perfect your shots on the go. For quick work, you can perform minor edits as photos are taken from within the Camera Roll. The iPhoto app, however, is available free for all iOS devices and offers a much more sophisticated set of editing tools, from contrast and saturation sliders to airbrushing effects and photo filters. Whichever you choose, both native apps make easy work of photo cropping.

Photos App

Step 1

Launch the Photos app and select the photo you would like to edit. Alternately, you can tap the thumbnail of an image you’ve just taken in the Camera app to open it in the Photos app.

Step 2

Tap “Edit” at the top and then select the “Crop” tool.

Step 3

Drag the borders of the image to adjust the crop dimensions. You can reposition the image or zoom in and out by dragging and pinching your fingers. To use a standard, preset crop measurement, tap “Constrain” and select a size from the available dimension options.

Step 4

Tap “Save” when your changes are complete.

Your iPhone offers a slew of photo editing tools that allow you to crop, refocus and otherwise perfect your shots on the go. For quick work, you can perform minor edits as photos are taken from within the Camera Roll. The iPhoto app, however, is available free for all iOS devices and offers a much more sophisticated set of editing tools, from contrast and saturation sliders to airbrushing effects and photo filters. Whichever you choose, both native apps make easy work of photo cropping.

IPhoto

Step 1

Launch the iPhoto app and select the photo you wish to crop.

Step 2

Tap the “Toolbox” icon and select the “Crop” tool, which looks like two opposing right angles.

Step 3

Tap the “Options” icon, which looks like three dots, and set your cropping measurements to a standard aspect ratio. You can, for example, set the crop to a standard 4″ x 6″ photo size. You can also manually crop the image by dragging the photo’s borders inward.

Step 4

Reposition the image within the cropping frame using your fingers — you can, for example, drag the image around with your finger or pinch to zoom in and out.

Step 5

Tap the dial at the bottom of the screen and then tilt your iPhone from side to side to rotate the image within the cropping boundaries. Alternately, you can pinch and rotate your fingers on the screen to do the same thing.

Step 6

Tap the “Share” icon, which looks like a square with an upward facing arrow, to share the photo via social network or email. There is no “Save” button; iPhoto automatically saves your edits to a new file as you make them. The original file is not overwritten.

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Student stations

The student stations are the computers that the students will use on a regular basis. The processing power of each computer is dependent on the lab’s purpose. Even the lowest-end computer currently on the market is sufficient to work on office software or for basic programming lessons. If the lab is to be used for video or photography production, video game programming or virtualization lessons, higher-end computers with more processing power and larger amounts of memory will be required. The operating system of the client workstation is up to the teacher and/or information technology team that will maintain the system, but it should be locked down to prevent students from installing unauthorized software, communicating on the Internet or doing other prohibited activity.

Management Station

The management station is the computer that the teacher will use. It will usually be identical to the client station. The management station, however, will have direct access to the server and the management system of the switch, be able to monitor the client stations and have a better access to external resource such as Internet or communication software. The management station also has better security because it makes a more interesting target for students wanting to play hacker and because of its access to external resources.

Server

The server in a computer lab can be used to fulfill several needs. It should store a copy of each workstation’s operating system. The workstations can be made to connect to that server to reinstall the operating system in its clean but configured state in case of a virus or simply as maintenance. The server can also be used to filter the external information the clients can access, for example, blocking Facebook but leaving the Library of Congress accessible. The server can also store the profile of each student and back up their work from session to session.

Switch

Networking is one of the most important parts of computer labs, and in many school computer labs, a hub or a switch is one of the ways this can be accomplished. The switch is the network equipment to which all the computers are connected. A switch can be configured so the clients cannot connect to each other, to limit communication to groups created for a specific project and to grant or refuse access to external resources.

Other equipment

Optional equipment can include printers, scanners, cameras, projectors and headsets. Each piece of equipment should be carefully considered, as the investment needed (for the printers, scanners, cameras and projector) or the high breakage ratio (for the headsets) can adversely affect the budget of the lab and its ability to run smoothly.

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Types

• The traditional one-room computer lab has morphed into three common types of computer labs: the classical lab with desktop computers, the mobile laptop lab that moves from classroom to classroom, and the mini-lab located in an individual classroom for a teacher to use in her daily work without having to leave her classroom . In addition to these three basic types, some schools and districts, like the Irving Independent District in Irving, Texas, are moving to a 1-to-1 laptop program where all students have their own laptop. This effectively makes every classroom a computer lab.

Function

• The computer lab serves as the center for teaching computer use to whole classes, usually by a specialist computer teacher. Classroom teachers also use the lab with their classes for research, or for creating technology-based projects. Technology specialists use the computer lab for teacher in-services where they instruct teachers on various aspects of using computers in educational settings. The traditional computer lab often serves as the location for networked printers and scanners that are used by the whole school.

Features

• A computer lab comes in several configurations: the most common are the “U” shape and the square models. The “U” or square configurations allow the teacher to monitor student activity. Several large tables in the center of the room provide space for offline work. Projectors, smart boards, scanners, printers, software and a variety of peripherals like digital cameras and camcorders are usually stored in computer labs.

Size

• The number of computers in a lab vary from a few computers in the case of a mini-lab to as many as thirty plus computers in a traditional lab. A mobile lab usually resides on carts that have power management systems so that the laptops can be charged when they are not in use throughout the day. Cart configurations vary with up to twenty laptops in one cart, although ten laptop carts are easier to move from classroom to classroom.

Considerations

• When designing a computer lab, three key issues must be carefully considered. The computer teacher needs to decide whether to utilize wall space for whiteboards or bulletin boards. Whiteboards are effective in instructional activities, while bulletin boards provide space for displaying student work. Scheduling is an issue that requires creative planning. The computer teacher or technology coordinator can place a sign up calendar on the front door of the lab so that teachers can reserve free lab time for their classes. A mobile lab has similar a scheduling problem that can be solved the same way. Monitoring student computer use is the third issue. Computer lab management software allows the computer teacher to control all computers in the lab from a single workstation. This is vital for keeping students on-task during whole class instruction.

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Computers allow students to perform good research and also communicate with different education providers. This help students understand the topic better by experiencing different forms of teaching. Computers also help teachers in tutoring  students. Teachers can also communicate with students using the computer. Teachers can form a group chat and interact with the students, also teachers can post homework online, and all students have to do is just go online, answer those question and hit submit. This also saves paper, making us save more trees. When students get projects, computers help students perform extensive research which gives them a wide range of answers to solving that problem.

Computers also help teachers recording grades, calculate average and keep track of students to see if they are present or absent. Teachers also use computers to create presentations for the class and also find videos that can make that particular topic easier to understand. Computers also help the little children. Parents can download math, science, reading and grammar softwares on the computer and this helps your child develop basic educational skills for school, also the kid at move at his or her own pace without feeling rushed.

To every advantage there is a disadvantage but looks like the advantages of computers outweigh the disadvantages of having computers in the class room. People feel computers are distract students from studying, they feel instead of researching with your system, you are rather playing games or chatting with a friend or watching a video. But these problems can be solved by setting restrictions on that system, like blocking internet access to some websites and grant access to only educational websites. People who also grew up in a pre-computer age feel computers are killing the feeling of the classroom and making things too easy for the kids, but that’s the point of computers or technology in general, to make research, education and our daily lives better.

In conclusion, I belive computers revolutionize the way we study, they make education easier and faster. We can easily find information with just a touch of a button. And also be released to different sources which show us different ways to understand a particular topic, equation or idea. I believe computers have helped the education world in general.

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Source: wikiHow

Part One of Five:
Getting Started

Part Two of Five:
Learning Basic Computer Commands

Part Three of Five:
Connecting to the Internet

Part Four of Five:
Increasing Functionality

Part Five of Five:
Troubleshooting Your Computer

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