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File Processing

 

File Processing Media

 

Introduction

In the previous lessons, we learned different techniques of creating and manipulating text. The problem is that we didn't preserve that text and, either when we closed the application or shut down the computer, all our valuable work was gone. Most of the time, after creating something using an application, you may want to keep it for later reference. You may even want to give or send it to someone else.

File processing consists of creating something on a computer and keeping it. The thing you keep is called information or datum. The plural of datum is data. In some cases, the word data can be used in both singular and plural forms. There are various issues related and different techniques used to keep data.

A medium is an object used to hold information in a computer. The plural of medium is media. There are various kinds of them.

Internal Hard Drives

The primary object used to hold information in a computer is called the hard drive:

Hard Drive

Everything (data) in your computer is stored in the hard drive. The hard drive is a rectangular box that contains some discs and other parts. The information stored in a hard drive is written on its discs. The information can be written to, erased from, copied or moved among discs. Although you will perform these operations, the operating system is in charge of deciding how the operations are carried out inside. You will not need to know what is going on inside.

The hard drive is inside of the computer, connected to another wide flat object called the motherboard, using cables. This type of hard drive is referred to as internal and this the most classic type.

When you purchase a computer, it already has a hard drive. Later on, if you know about computers and you have some complaints about your hard drive, you can either add a second one to your computer or you can replace the hard drive in your computer.

External Hard Drives

Until recently, the hard drive was traditionnally thought of as a piece of hardware inside the computer. For this reason, it couldn't be carried away easily: you had to open the computer, disconnect the cables, and then remove the hard drive. Even then, some other issues were related (such as the type of cable, etc) so much that people were not in the habit of carrying a hard drive from one computer to another. Fortunately, another technology was developped.

Another type of hard drive stays outside of the computer and it is referred to as external. Here are examples:

An external hard drive is usually connected to the computer using a cable to a port (USB) outside the computer. What makes it valuable is that, by simply disconnecing its cable, an external hard drive can easily be carried from one computer to another. And because the external hard drive doesn't have the same particularities of cables (IDE vs SATA), it can easily be connected to almost any common computer (PC).

To use a hard drive, there is no particular action you must perform. When we get to the issues of storing data, we willl see that you don't need to know what the hard drive does; you simply know and confidently believe that it's doing its job.

If you purchase a computer, you usually don't get it with an external drive. If you need one, you can acquire it, either from purchase or getting it from somebody. The external hard drive is fairly easy to install. You primarily connect a (USB) cable from the back of the hard drive to a (USB) port on the computer. In most cases, it should be ready to install (Plug n' Play) or it may quickly install the software (driver) it needs to function. In some cases, after inserting the cable and turning the device on, a window may come up asking you to install something (a driver), which you would also have received from the manufacturer.

Internal CD Drives

One of the problems with external hard drives is that, sometimes they can be heavy (not too heavy but still). Another problem is that, to use them on another computer, you must have the right cable and you must physically connect them. The remedy to this is to use an object that holds its information but can be ready by a recognizable drive.

A CD drive is an object that can be used to store information on a disk called a compact disc (CD):

Notice that the front of the machine is marked compact disc.

This type of CD drive is installed inside of the computer using cables to connect it to a wide flat object called the motherboard. The front of the CD drive can be seen and accessed from outside the computer, usually from the front of the PC. This type is also referred to as an internal CD drive.

Most computers come with a CD drive (or a DVD drive that we will see in the next section; in reality, at the time of this writing, most computers don't come with a CD drive anymore). Otherwise, you can purchase one and install it. The installation is fairly easy but you must open the computer, recognize the cables and connect them. When in doubt, either ask a friend or family member, or take it to a computer store to install it (but they would ask you a fortune for something so insignificant).

External CD Drives

Another type of CD drive stays outside and it is referred to as external. This type is usually connected to the computer through an external port (USB). Here is an example:

Like the internal hard drive, the CD drive uses a round disc to store its data. While the hard drive holds its own many discs inside, the CD drive doesn't actually have a disc. You insert the disc when you think it necessary, and you can insert only one disc (you will never insert a disc in a hard drive since you will never open it anyway). The CD drive can read regular data but it can also play CD musics.

In early days, the CD drive was used only to read the data on a disc. Most CD drives nowadays are also used to write to a disc. They are called CD writers or CD burners. As such, the CD writer can be used to both read from, and write to, a disc.

To use a CD drive, the device usually has a button in the front. You can press that button.

If the CD tray doesn't come up when you press the button, may be there is a problem. If you suspect a problem, take a paper clip and open it. Insert one of its ends to the small whole on the CD drive.

This would open a tray on which you place the CD medium. You can then press the same button or push the tray itself. This would put the tray back. What happens depends. A window may come up asking you whether you want to see the contents of the CD medium or you want to place the music on it. In some cases, nothing may happen.

If you purchase a computer, it usually doesn't come with an external CD drive. If you need it, you must purchase it. As mentioned in the previous section, at the time of this writing, the CD drive is a little outdated, replaced by the DVD drive.

Internal DVD Drives

As you can expect, the CD has some limitations. For example, it can hold only a specify amount of information and it can play only music. To overcome some of its limitations, there is the DVD (digital video disc) drive. This drive looks like the CD drive and they have the same dimensions:

Notice that the front of the machine is marked with DVD. As mentioned for the CD drive, this device is connected to the inside of the computer using cables but its front is accessible from the outside.

If you purchase a computer, it usually comes with a DVD drive. If not, or if yours stops functioning or you don't like it, you can purchase one to install it. To do this, you must open the computer and connect the cables appropriately. Normally, the installation is not difficult because the device usually comes with enough documentation. If you have some doubts, you can ask a friend or a family member to install it for you. If you have some money, you can take it to a computer store to install it for you.

External DVD Drives

There is also an external DVD drive. Like the hard and the CD drives, the external DVD drive connects to the computer using a (USB) cable connected to a port on the computer.

You use a DVD drive exactly the same way you use a CD drive: you can press the button in front of the device, which would open a tray on which you place the DVD medium. After placing the medium on the tray, you can press the same button or push the tray itself to put the tray back. Once again, what happens depends on the contents of the DVD, if you had put one.

Flash Drives

A flash drive is a small drive that can be used to hold data. Here is what it looks like:

To use it, you insert its metallic side in a USB port on the computer. Once you do, it turns itself on and a window may come up asking you what you want to do. In some cases, the drive would need to install something (a driver) for it to work.

When you purchase a computer, it doesn't come with a flash drive. If you need it, you must acquire it, which you can do through purchase.

Simple Disc Management

When a drive has been installed in the computer or inserted on a port, the operating system must recognize it. Once it does, for a computer that runs Microsoft Windows, it assigns a letter to it. In Windows Explorer or My Computer, a drive is represented by a letter. Here are examples:

Each letter, in this case A, C, D, E, F, and G represents a drive. Most computers should have less drives than that and some computers can have more drives than that. In some cases, a letter may not represent a real drive physical drive (it may represent a partition among many partitions on the same har drive). To distinguish a letter of a drive from letters of normal words, the letter of a drive is always followed by a colon ":". In Windows Explorer or My Computer, the letter of a drive is also included in parentheses.

In most cases, you should accept the letters, In some cases, you may need to change them. For example, if you insert a flash drive, you hear a sound that the computer has recognized it, but the content of the drive doesn't show, or the drive letter is not (automatically) assigned (by the operating system). The problem could be that the letter the operating system attempted to assign to the drive is already taken but the operating system didn't attempt to assign another letter.

To manage the letters of the drives, you can open the Computer Management MMC. To do this, you can right-click My Computer and click Manage. Then, in the left frame, click Disk Management:

One of the actions you can perform here consists of changing a drive letter. To do this, you can right-click a drive letter in the top-right frame or a section in the lower-right frame and click Change Drive Letter And Paths...

This would open a dialog box that you can use to change the letter.

A Document

 

Introduction

When you open an application, such as a text editor, it displays an empty area with a blinking caret:

In the same way, if you open a graphics application or a spreadsheet, it also displays an empty area, waiting for your work. You can then start performing the type of assignment that the application is expecting. For a graphics application, you can start drawing or loading pictures. For a spreadsheet, you can start entering numbers and performing calculations.

When you start entering text in a text editor or a word processor, you are said to create, or work on, a document. If you start drawing shapes or manipulating pictures in a graphics application, you are said to work on a document. If you start entering numbers and performing calculations in a spreadsheet, you are said to work on a document.

Practical Learning: Creating a Document

  1. To start WordPad, click Start -> (All) Programs -> Accessories -> WordPad
  2. In the window, type Welcome to Windows

Saving a Document

After creating a document, you may want to preserve it for later use. Preserving a document is referred to as saving it. You have many options and this may depend on the application you are using. In most cases, if an application was created using the standards described and recommended by Microsoft, to save the document, on the main menu, you can click File -> Save:

  • If the document was never saved before, a dialog box would come to assist you
  • If the document was saved previously, it would be saved behind the scenes and the new version would include the new chchanges

A document can also be saved when you attempt to close an application:

  • If you create a document or modify one, if you close the application (or the window), you will be asked whether you want to save it. If you want to save it, you should click Yes. If the document was not saved previously, a dialog box would come up.
  • If you have modified a previously saved document and if you attempt to close the application (or the window), the computer would ask you whether you want to save the document. If you want to save it, you should click Yes. In this case, the new version of the document would keep the changes you made. If you click No, the document would revert back to what it was before it was opened or the previous time it was saved

When saving a document for the same time, you must give it a name and a location.

Folders

 

Directories

To make it possible to easily recognize its information in a computer that runs Microsoft Windows, a drive, such as those we have reviewed above, uses some units. The primary unit is called a directory. In Windows Explorer or My Computer, a directory is represented by a letter. Here are examples:

When (the disc of) a drive is created, it doesn't contain directories. This is because the manufacturer doesn't decide how and on what type of computer the drive will be used. When a drive is installed on a computer, the operating system decides about the drive, creates it as a directory and assign a letter to it. You can store a document on a drive but this is not recommended.

Creating a Folder

To better organize the information that it contains, one or more units can be created on a drive. Each unit is called a folder. When (the disc of) a drive is created, it doesn't contain folders. When the operating system is installed, it creates a few folders. You also can create a folder and you have many alternatives.

When it comes to folders, a drive is called the root folder or simply, the root. To create a folder in the root, in Windows Explorer or My Computer:

  • In the left frame, click the drive. On the main menu, click File -> New -> Folder and give it a name
  • In the left frame, click the drive. In the right frame, right-click a white empty area, position the mouse on New and click Folder. Then give it a name

You can also create a folder inside of another. The folder that will contain the new one is referred to as the parent folder. The other will be referred to as a child folder. To create a folder in another folder, in Windows Explorer or My Computer:

  • In the left frame, expand the drive by clicking its + button. Under the drive, click the folder name. If the new folder will be created inside of another folder that itself has a parent, expand it also and click the parent folder. On the main menu, click File -> New -> Folder and give it a name
  • In the left frame, click the drive and click the parent folder. In the right frame, right-click the parent folder, position the mouse on New and click Folder, then give it a name

You can also create a folder when saving a file. To do this, in the dialog box that comes up, click the Create New Folder button and give it a name.

The Name of a Folder

There are some suggestions you should follow and various rules you must observe when naming a folder:

  • The name of a folder can be a single letter or a digit
  • The name of a folder can also be a single special character except the following
  • The name of a folder can be a combination of letters, digits, and some special characters
  • The name of a folder cannot contain the following special characters: | > / : \ < ? * and "

As a suggestion, you should use a name that indicates what is stored in the folder. This makes it easy to find information (sooner or later, you will look for something in your computer).

Introduction to Files

In our introductions, we defined a document as what you create in an application. In a word processor, the characters you type constitute a document. For a graphics application, the drawings you perform or the picture you manipulate is called a document. In order to keep such a document for later use, you must store it somewhere.

A file is an object used to hold a document. Put it another way, in order to have a file, you must save a document. We have mentioned how to save a document. Like a folder, you must name a file when saving a document. The name of a file follows the same rules we defined for a folder.

Practical Learning Practical Learning: Saving a Document

 
  1. To save the document, on the main menu of WordPad, click File -> Save
  2. In the Save As dialog box, make sure the My Documents folder is displaying in the Save In combo box. In the File Name combo box, change the name of the file to wow
     
    Save As
  3. Click Save

File Management

 

Bits and Bytes

To hold information, a medium such as a hard disk uses a system that resembles a combination of small boxes. Let's illustrate it as follows:

Bit 0

This box can hold only a small piece of information. It can only be either 0 or 1. When the box is empty, it holds a value of 0. When it is full, it holds a value of 1:

0 1

You can represent a piece of information with one of two states. This box used to represent a value is called a binary digit; in its abbreviated form, it is called a bit (for binary digit). 

This produces the following binary combinations: 0000, 0001, 0010, 0011, 0100, 0101, 0110, 0111, 1000, 1001, 1010, 1011, 1100, 1101, 1110, 1111 = 16 combinations. When using the decimal system, these combinations can be represented as 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, and 15.

This combination is also a system that the computer uses to count bits internally. This technique is valuable and allows you to always identify a number as a divider of 4.

When all bits of a group of 4 are 0, the combination has the lowest value, which is 0000. Any of the other combinations has at least one 0 bit, except for the last one. When all bits are 1, this provides the highest value possible for a group of 4 bits. The lowest value, also considered the minimum value, can be represented as 0. The highest value, also considered the maximum, can be expressed in decimal value as 24 (2 represents the fact that there are two possible states: 0 and 1; 4 represents the fact that there are four possible combinations), which is 16. This produces 16 because 24 = 16.

A combination of 8 consecutive bits is called a byte. The bits are counted from right to left starting at 0:

You can represent a byte using a combination of 0s and 1s. If you have the patience to create combinations of bits using the boxes as we did for the group of 4, you would find out that there are 256 possible combinations. Another way to find it out is by using the base 2 technique:

27 + 26 + 25 + 24 + 23 + 22 + 21 + 20
= 128 + 64 + 32 + 16 + 8 + 4 + 2 + 1
= 255

Therefore, the maximum decimal value you can store in a byte is 255. Remember that the byte with all bits having a value of 0 has its value set to 0. Since this byte also holds a valid value, the number of combinations = 255 + 1 = 256.

The only type of information you can store in a byte is a character or symbol, such as a readable letter from the alphabet: a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u, v, w, x, y, z, A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, and Z. Besides these readable characters, a byte can also hold one digit: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9. A byte can also hold a readable or non-readable symbols such as ` ~ ! @ # $ % ^ & * ( ) - _ = + [ { ] } \ | ; : ' < ? . / , > "

This means that a combination of 8 bits, called a byte, is enough to represent one symbol recognized in the English language. In this globalization word, a computer also needs to be able to store characters from other Latin-based languages such as letters from Franšais or Espa˝ol. To make this possible, instead of 8 bits, the operating system must use 16 bits. A combination of 16 consecutive bits is also called a word.

A group of 1000 bytes is supposed to be called a kilobyte but, based on the way the computer calculates the bits, a group of 1024 bytes is called a kilobyte or KB. A group of 1,000,000 bytes is called a megabyte but actually it is a group of 1,024,000 bytes that is called a megabyte or MB. A group of 1,000,000,000 bytes or actually a group of 1,073,741,824 bytes is called a gigabyte or GB.

The Size of a Drive

Because a drive cannot have unlimited space, it is recognized for its size. The size of a drive can be measured by, or specified in, MB or GB. For example, a typical CD can hold 700MB of data. A regular DVD can hold information up to 4.7GB in size. The sizes of hard drives are very varied. To find the size of a hard drive in your computer, from either Windows Explorer or My Computer, you can right-click the drive letter and click Properties. Here is an example:

The Size of a File

In order to keep track of the various files in a computer, each file has a size. The size of a file can be measured in bytes, kilobytes, or megabytes. To know the size of a file, in either Windows Explorer or My Computer, you can right-click it and click Properties.

 

 

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