TyroCity: Computer Notes

Number System

TyroCity.com — Sat, 12 Jul 2014 05:41:42 +0000

Conversion Techniques

1. Decimal to
a. Binary

/2 (Integer Part)
*2 (Decimal Part)

b. Octal

/8 (Integer Part)
*8 (Decimal Part)

c. Hexadecimal

/16 (Integer Part)
*16 (Decimal Part)

2. Binary to
a. Octal

Table (3-bit)

b. Decimal

*2n For eg. (1011)2 =1*23+0*22 +1*21+1*20

c. Hexadecimal

Table (4-bit)

3. Octal to
a. Binary

Table (3-bit)

b. Decimal

*8n For eg. (2341)8 =2*83+3*82 +4*81+1*80

c. Hexadecimal

Construct table of:
- Octal-Binary (3Bit)
- Binary-hexadecimal (4Bit)

4. Hexadecimal to

a. Binary

Table (4-bit)

b. Octal

Construct table of:
- Hexa-Binary (4Bit)
- Binary-Octal (3Bit)

c. Decimal

*16n For eg. (12A8)2 =1*163+2*162 +10*161+8*160

1’s and 2’s Complement

9’s and 10’s Complement

Computer Science Grade-11 2069

TyroCity.com — Sun, 18 Aug 2013 05:41:42 +0000

Candidates are required to give their answers in their own words as far as practicable. The figures in the margin indicate full marks.

Full Marks:- 75
Pass Marks:- 27
Time:- 3hrs.

Group A
Long answer questions

Attempt any three questions. 3×10=30

What is an operating system? Explain the functions of operating system.
What is memory in the computer system? Explain primary and secondary memory.
What is programming? Differentiate between compiler and interpreter.
What is Boolean algebra? Describe AND gate, OR gate, NOT gate and NAND gate symbol and Truth Table.

Group B
Short answer questions
Attempt any nine questions. 9×5=45

Why computer is known as versatile and diligent device? Explain.
What is mobile computing? Explain. Or Differentiate between analog and digital computer.
Convert (110111101)2 binary number into octal number.
What is BUS in terms of computer architecture? Explain.
Differentiate between Impact and Non-impact printers with examples.
What is internet? Write down the uses of internet. Or Explain the features of word processor.
What is web page? List the features of web page. Or Write down the advantages and disadvantages of DBMS. (Old)
What is CPU? Write down the functions of CPU.
Explain the types of programming errors with examples.
Subtract (1100)2 from (1111)2 using 1st and 2nd complement method.
Write short notes on:
- Modem
- Trackball

Computer XI Questions

TyroCity.com — Sun, 18 Aug 2013 05:41:42 +0000

Questions

Model Question for Computer Science Class 11

TyroCity.com — Sun, 18 Aug 2013 05:41:42 +0000

GRADE : 11
FOR : 2070
Time : 3hrs
F.M. : 75
P.M : 27

Group A (Long Answer Question)
Attempt ALL the questions. [3 × 10 = 30]

Draw a well-labeled diagram of typical architecture of a computer system and explain the main function of Control Unit and ALU. [4+3+3] 2.a. What is an operating system ? Explain any three function of an operating system. [1 + 6] 2.b. The “WiMP” environment is much more user-friendly, why ?

OR
2.a. What is cell addressing and explain different types of cell addressing used in spreadsheet. [5]
2.b. Write a tag to design your personal web page to link photo family, background and banner page using frame. [5]

3.a. Define flowchart and pseudocode. Explain their significance in programming. [5]

3.b. Write a pseudocode to accept any three numbers and output the largest among them. [5]

Group B (Short Answer Questions)
Attempt any NINE questions. [9 × 5 = 45]

Classify the computers according to their generation based on the technology used. [5]
Differentiate between analogue and digital computer, explain with examples. [5]
What do you mean by number system? Why do digital computers use binary numbers for their operation ? [2 + 3]
Convert these numbers. [5]
- (126)10 = (?) 2
- (11011)2 = (?) 10
- (57)8 = (?) 2
Perform following operations.
- 1011 – 1001
- 1110 + 1110
State the Demorgan’s theorem and verify it. [5]
What are logic gates? Construct the truth table of NOR operation. [5]
Write short notes on (any two) : [5]
- IDE
- SCSI
- Wave Camera
What are uses of internet ? Write any five search engine name. [5]
Differentiate between System Software and Application Software with examples. [5]
What are DPT features in MS-Words? Write three features of Presentation Packages. [2 + 3]
Write an algorithm and flowchart to print the word “Hello” ten times using “while loop” [5]

File Handling In Windows 3.1

Computer 11 Notes — Sun, 08 Apr 2012 05:41:42 +0000

Introduction to file handling

Windows being a GUI, gives better flexibility and easier to use for file management. Using the File Manager feature of Windows, one can easily copies, move, delete, rename files and also create and remove directory. This avoids the painful task of remembering all the file management DOS commands.
Windows can run two types of applications, standard DOS based applications and Windows based applications. DOS based applications are standard DOS programs such as WordStar, dBase etc. developed to run in DOS environment, and not specifically meant for windows. Whereas a windows application is specifically developed to run under Windows environment which support GUI.

Objectives

At the end of this lesson you would be able to:

Appreciate the GUI feature of windows
Understand the file and directory handling in windows
Use file manager for file handling in windows
Sort file using file size, name, type
Search and locate file(s)
Do file copy, move from floppy disk to hard disk drive and vice versa.

Directory and file management in windows

Windows provides file manager for manipulating directory and files of a system. It is an essential part of Windows and run like any other windows program. Main program consists the icon for file manager. Double clicking on the file manger icon activates it from the Main program group. Other way of activating it is to highlight the file manager icon and hit the return key.
File manager can be closed like any other windows program. File manager can be minimized while running some other application and expanded once the execution is over. The total amount of diskspace, free diskspace available, the size of the selected file is shown for the currently open directory on the status bar, which appears at the bottom of the file manager.

1. Drive window
Currently selected drive is displayed as another windows within the File Manager window. The command to resize, move or minimize is same as that of any other window. The only difference is that it is divided in two parts; right one displays the directory structure of the currently selected drive and the left part displays the contents (such as files, sub-directory etc.) of the currently selected directory.

2. Directory operations
File Manager provides the features to manage all the drives in your system and/or connected to your system through network. It allows to copy, move or delete files within a drive, between drives of the system and systems connected through network. Once the drive is changed, directory and files under the newly selected drive will be displayed in the current directory window.

3. Changing disk drives
To change drive, click on the desired drive icon or press and the designated drive letter such as C, D E etc. Other way of selecting a drive is to click on the Disk option of the File Manager menu bar, and select the desired drive letter.

4. Creating a new directory
A new directory or sub-directory under an already existing directory can be created using File Manager. First click on the File menu option of the File Manager. This will bring up the pull down menu having Create Directory. Selecting this option will activate the Create.
Directory dialog box with current directory path. To create a sub
directory under the current directory, type down the new sub-directory name in the text box. To create a sub-directory under some other directory, type the entire path in the name text box. To finish the entry and create the new sub-directory, click on the OK button.

5. Changing directory
To go to the desired directory under the currently selected drive, double click on the directory name. This will make the selected directory as the currently active directory and all the sub-directory and files under this directory will be displayed at the right pane of the document window.
File manager has the flexibility of displaying different groups of files in the currently selected directory. Click on the View option of the File Manager menu bar, which will activate the pull-down menu with option ‘by file type’. Selecting this will bring up the ‘by file type’ dialog box. Use the wild card characters to enter inn the name text box, the desired file type you want to see.
In file manager, it can also be specified what all information for files can be displayed. In addition to the file name, file path one can display file size, date and time it was created/or last modified etc. To display all file information, select the view option on the file manager menu bar and activate the option ‘all file details’.
In file manager, sub-directory and file under the currently selected directory are displayed in alphabetical order. However they can also be displayed in order of file type, date or file size. To change the displays option, select the VIEW option on the menu bar and selected the desired option. Available options are:

Sort by name: Displays all files in alphabetical order of file name.
Sort by type: Displays all files in alphabetical order of extension name
Sort by Date: Displays File in order of creation/last modification date.
Sort by Size: Display all files in order of File Size.

File operations

File Manager provides tools such as copy, rename, move, rename for management of files within directory, between directories and also between drives.

1. Copying a diskette
Like Disk copy of DOS, windows also have the tool in File Manager for making copies of disk. The source disk replaces the content of the target. However the target disk type and size should same as that of source disk. If an unformatted disk is used in target drive, the target disk is formatted as that of source disk type and size while copying the files. This copy option is very useful for making back-up copy.
Insert the source disk into the drive and select the DISK option of the file manager menu bar, and activate the ‘Copy Disk’. This will copy the files from the source disk into the memory. Now select the target drive from the copy dialog box and click on OK button. This will start the coping process from the source to target disk.

2. Copying/moving directory or files

In file Manager, one or more files or Directory can be copied or moved into different location using two different methods; Drag-and-Drop method and Keyboard method.

1. Drag-and-Drop method
File Manager has the capabilities of copying or moving files and directories in more interactive and visual ways as compared to MS-DOS. Open the source directory select the files to be copied and then drag them in to the desired target directory, another drive icon, another directory window or to a file list in a different directory window and drop them. Confirm the copying operation, by clicking on the OK button of the dialog box. This will copy the selected files in to the target drive. If the file(s) to be copied is/are already presents on the destination directory or drive, confirm replace message by clicking on the yes button of the dialog box.

2. Using Keyboard
Instead of using mouse for the above operation, one can alternatively use the keyboard to select copy and move command. As in the case of drag-and-drop method, the destination can be a directory window, directory icon or drive icon. Click on the desired file name to be copied or use the direction key to highlight it. Select the COPY or MOVE option from the File menu bar of File Manager as per the requirement.
Alternatively press f8 for copy or f7 for move operation to start. As in the case of drag-and-drop method, copy or move dialog box appears on the screen. Enter the destination path or drive. If the destination directory does not exist, it will ask whether to create a new one. To start the operation, click on the OK button or press enter key ().

Deleting files and directories

File manager provides greater flexibility in deleting files and directories. However in the case of network drive, one cannot delete files or directories if he has not the privilege or permission of doing so. File Manager allows to delete an entire directory including all its files and subdirectory in a single command. However, in DOS, one first need to delete all the files and sub-directory of the desired directory to be deleted.

Select the file(s) or directory to be deleted (alternatively use tab to move the cursor to the desired location and use direction keys to select the files). Activate the Delete option from the File menu bar of File Manager and the delete dialog box appears on the window desktop. To delete the already select files or directory, click on the OK button. To delete other files or directory, enter the file name or path and click on the OK button.

This will activate directory delete dialog box. Click on yes button to confirm the deletion. Click on yes to all to delete all selected files or click on Cancel button to cancel the delete operation.

File renaming

File Manager allows changing the name of a file with a restriction that the new file name should follow the DOS file naming conventions. The new file name should not be more than eight characters long with an optional three characters extension or secondary name with permissible set of characters.

First select the file to be renamed, and then chose the Rename option from the File menu bar of File manger. The Rename dialog box appears with name of the currently selected file in the From text box. Now enter the new name for the file in the To text box and click OK button or press Enter key. This completes the renaming process.
Note: One can use wild card characters for renaming files.

Searching for files and directories

File manager provides the tool to search a file, a group of files or subdirectories. This is particularly helpful, if you know a particular file is on your disk, but you don’t remember where the file exists. Here you can conduct a search on your disk, directory to locate the file. The result is displayed in Search Result window, which can be resized, minimized or maximized, closed the same way as other window.

Click or select the directory to be searched and then choose search option from the file menu. Specify the filename, or use wildcard character (such and * or?) in the search for text box to search for a group of files or directories that have related file names or extensions. The Search Result windows will contain all the files that meet the search criteria. To cancel the search operation, press esc key.

Working with floppy disks

At times one need to copy files onto a floppy as backup or copy file from floppy to hard disk for further processing of files. File manager provides tools to work with floppy disks.

1. Formatting a floppy
Before using a new floppy to receive data, it has to be prepared for that. File Manager format command allows you to prepare a new/old floppy to receive data. The format command has three options, which are optional.

Label
As the name suggests, it is a name for the formatted disk to identify it. A label or volume label should not more than 11 characters long.

System disk
While formatting a disk, it can be opted to make the disk a system or startup disk. System disk is used to boot the system from a floppy drive. When opted, all the system files are copied into the specified area called system area or boot sector of the floppy drive. System disk comes handy, in case the hard disk is not working or one needs to bypass booting from hard disk for any reason.

Quick format
This option is available for disk that has already been formatted. When selected, file Manager just removes all information about directory and files from disk, making it faster as compared to standard format procedure. However Quick Format does not check the disk for bad sectors.
To format a disk or floppy using file manager, insert the disk into the drive and select format disk option from disk menu bar. From the list of drives, select the appropriate drive letter. All the required parameters are adjusted according to the selected drive.

Choose the option such as label, system disk or quick format. In case of Label option, specify the volume label name for the disk. Complete the other areas of the dialog box and click on ok button. This completes the entry and file manager starts formatting the disk according to the specification given.

In-text questions 1
Choose the best answer for each of the following questions.
1. Windows is a

System Software
Database Software
GUI based Software
None of the Above

2. Which are the following types of Icons used by Windows

Database, operating system
Program, document, application
Only program
None of the above

3. Which of the following on a command button indicates a link to another dialog box

/
*
..
None of the above

4. File manager is a part of which group of Windows
Program Manager

Main
Application
None of the above

5. Which of the following groups of Windows contain all executable software found on your hard disk.

Main
Print Manager
Application
None of the above

6. Which of the following allows all types of file manipulation such a copy, move etc.

Print Manager
File Manager
System setup
None of the above

What you have learnt

This lesson discussed Windows's graphical user interface (GUI) in a great length. In the beginning it discussed what is directory and file management. Then with examples it explained how to do directory maintenance in-terms of create, delete and change directory. It also discussed how to sort files by name, type, size and dates. Here you learned how to file operation in windows using File manager and what is drag and drop method. At last it explained how to search for file and directory and how to work using a floppy diskette in windows.

Feedback to in-text questions 1
1. 3
2. 2
3. 3
4. 2
5. 3
6. 2

Types Of Computers

Computer 11 Notes — Sun, 08 Apr 2012 05:41:42 +0000

Super Computers
Main Frame Computers
Mini Computers
Micro Computers

Example of Super Computer:
CRAY Research :- CRAY-1 & CRAY-2, Fujitsu(VP2000), Hitachi (S820), NEC (SX20), PARAM 10000 by C-DAC, Anupam by BARC, PACE Series by DRDO

Disk Operating System (DOS)

Computer 11 Notes — Sun, 08 Apr 2012 05:41:42 +0000

Introduction to disk operating system

When the computer starts, it starts the operating system that takes the control of the machine. An Operating System is a set of programs that help in controlling and managing the Hardware and the Software resources of a computer system. A good operating system should have the following features:

Help in the loading of programs and data from external sources into the internal memory before they are executed.
Help programs to perform input/output operations, such as:

Print or display the result of a program on the printer or the screen.
Store the output data or programs written on the computer in storage device.
Communicate the message from the system to the user through the VDU.
Accept input from the user through the keyboard or mouse.

Objectives

At the end of this lesson, you would be able to:

Explain the concept operating system
Discuss the functions of operating system
Understand the procedures of loading operating system into the memory
Use file management features of operating system
Create separate locations for logically related files
Copy files from one computer to another
Use Windows for File Management

Disk operating system

As the name suggests, the operating System is used for operating the system or the computer. It is a set of computer programs and also known as DOS (Disk Operating System). The main functions are to manage disk files, allocate system resources according to the requirement. DOS provides features essential to control hardware devices such as keyboard, screen, disk devices, printers, modems and programs.
Basically, DOS is the medium through which the user and external devices attached to the system communicate with the system. DOS translate the command issued by the user in the format that is understandable by the computer and instruct computer to work accordingly. It also translates the result and any error message in the format for the user to understand.

1. Loading of DOS
The BOOT Record into the computer memory loads DOS (Disk Operating System). BOOT Record in turn is triggered by ROM program already there in the computer.
The system start-up routine of ROM runs a reliability test called Power On Self Test (POST) which initializes the chips and the standard equipment attached to the PC, and check whether peripherals connected to the computer are working or not. Then it tests the RAM memory. Once this process is over, the ROM bootstrap loader attempts to read the Boot record and if successful, passes the control on to it. The instructions/programs in the boot record then load the rest of the program. After the ROM boot strap loader turns the control over to boot record, the boot tries to load the DOS into the memory by reading the two hidden files IBMBIO.COM and IBMDOS.COM. If these two are found, they are loaded along with the DOS command interpreter COMMAND.COM. COMMAND.COM contains routines that interpret what is typed in through the keyboard in the DOS command mode. By comparing the input with the list of command, it acts by executing the required routines/commands or by searching for the required routine utility and loads it into the memory.

Computer files in DOS
A file may contain a program or any other kind of information. Generally, a file must be given a name that can be used to identify it. DOS (Disk Operating System) permits the user to assign a name consisting of two parts to a file – primary and secondary names. Primary name can be of a maximum of eight characters consisting of Characters, Alphabets, Number and Hyphen), and the Secondary name should consist of three characters, which is optional. The primary name and the secondary (or extension) name, if any, are to be separated by a dot (.).
Primary name can be linked to proper name, whereas extensions are like surnames of people. Using an extension with the file name is preferable, though optional. However, once the extension is specified, using the complete name (primary name and extension, with the period separating them can only refer the file). Using extensions can be an excellent way of naming a file so that it can be identified easily.

DOS (Disk Operating System) has a way of showing which disk drive is currently active. The floppy disk drives are assigned alphabets A and B, whereas the hard disk drive is assigned the alphabet C. If your PC has a single floppy drive, the drive would be A and if it has two, they would be termed as A and B. If your PC includes a hard disk, besides a FDD (Floppy Disk Drive), the drive names would be A and C. If the prompt is A, then it implies that the first floppy disk drive is active. Where as the DOS prompt would be C, if the hard disk is active. Data as well as instructions reside in a file stored in a disk.

Directory structure in DOS
The files in the computer come from various sources. Some files come with DOS, while other come with publications such as a word processor. These files contain codes and other information that is necessary to make the computer application operational. Before long, there will be hundreds or even thousands of files in the computer, which can make it difficult to locate specific files.
The names of all the files created in a disk are stored in its directory. Directory is just like a file folder, which contain all the logically related files. DOS files are organized in a hierarchical or an inverted tree-like structure. The general analogy is with a file cabinet containing a number of drawers, which in turn may contain folders. The content of these folders is the needed information.
The file cabinet here is the ROOT DIRECTORY, the drawer is INDIVIDUAL DIRECTORY, the folders are SUBDIRECTORYand the information in these folders may in turn be classified as FILES.
Otherwise, the large number of files that get created for various purposes in a disk can make the directory huge and difficult to view and manage. Therefore, DOS enables the user to organize the files in a disk into directories and sub-directories in a hierarchical structure. Directories can contain other directories. A directory within another directory is called a sub-directory.
Of course, there may be sub-directories of sub-directories, but a file name is the furthest you may descend down the (inverted) tree of directories and files. Thus, a file name corresponds to a tree leaf, a sub-directory to a branch, the directory to the trunk, and the root directory to the root of the tree, hence the name ROOT DIRECTORY.
Command.com (Personal) Autoexec.bat (Accounts) Pk.bat LEAVE INSURANCE GPF PENSION LOAN
The directory/sub-directory is represented in bold letters.

Directory command
The content of each of the sub-directory cannot be viewed unless it is made active, or a sub-directory is specified as part of the DIR command. Doing either of these requires an understanding of the concepts of navigating around the disk.
The directory, the user is in at any point of time, is called the WORKING/PRESENT/CURRENT directory. DOS indicates which directory you are in by displaying the directory’s name in the command prompt. For example, the following command prompt indicate that you are in the DOS directory: C:DOS>. Knowing which directory is current helps you find files, and to move from one directory to another more easily. Typically, the ROOT DIRECTORY () is the initial working directory. The entire specification of directory from root is called a PATH. By itself, the DIR command is applicable to the working/present directory. The names of the sub-directories at adjacent levels are separated by backslash (), while specifying the path to be followed while traveling to a sub-directory.

Using path to specify the location of files
A path is the route that leads from the root directory of a drive to the file you want to use.
For example, to access the NOS.LET file in the LETTER subdirectory of NOS directory, DOS must go from the ROOT () directory through the NOS directory to the LETTER directory.
To specify the same path at the command prompt, you would type it as shown in the following illustration:
C:NOSLETTERNOS.LET
This is the path or route to the file NOS.LET. The first letter and the colon (C:) represent the drive the file is on. The first back slash () represents the root directory. The second backslash separates the NOS directory from the LETTER sub-directory. The third backslash separates the LETTER sub-directories from the file name, NOS.LET.
Note: MS-DOS recognizes path up to 67 characters long (including the
Drive letter, colon, and backslash).

DIR command
The DIR command gives the list of is there on the disk that is mounted on the active drive.
Syntax : C:> DIR A:> DIR
Example
A:> DIR
Volume in drive A has no label
Directory of A:
COMMAND COM 23612 10-20-88 11.30a
DISKCOPY COM 4235 10-20-88 12.00p
FORMAT COM 15780 03-12-89 12.00p
3 file(s) 325013 bytes free
A:>
As can be seen, on typing DIR followed by key at DOS prompt, five columns of data followed by the number of files and bytes that are free in the disk are displayed. The first column contains the primary name of each file resident on the disk. However, most files are named with an extension, which appear in the second column. Whereas, the third column contains the size of the file in bytes, and the fourth and fifth columns show the date and time on which the files was created or last modified. The last line displays the number of file(s) and remaining disk space free in bytes. It is important to note that the DIR command only displays the names of the files and not their contents.

Changing a directory
All the names displayed using DIR command that have
besides them are directories. You can see the list of files in another directory by changing to that directory and then using the DIR command again.
The Change Directory (CHDIR) or CD command enables the user to travel around the directories in a disk. Type the CD command at the command prompt.
Syntax:
A:> CHDIR {path} or a:> CD {path}
Examples : (Refer to the figure)
1. A:>CD NOS
This command makes the NOS sub-directory under the root directory () active.
2. A:>CD NOSLETTERS
The backslash indicates the root, and LETTERS, which is a sub-directory under the NOS directory, becomes the working directory.
3. A:> CD
The root directory becomes the working directory; i.e. you will change back to the root or main directory. The slash typed in this command is a backslash (). No matter which directory you are in, this command always returns you to the root directory of a drive. The root directory does not have a name, it is simply referred to by a backslash ().

Making or creating directory
As the number of files increases in a disk, a need is felt to organize them in a meaningful way by creating sub-directories to store a group of logically related/similar files.
To create a directory, DOS provides the MKDIR (Make Directory) or MD command.
Syntax:
A:>MKDIR [drive:] {pathname} or A:>MD [drive:] {pathname}
Square brackets indicate that [drive:] entry is optional.
The MD or MKDIR command creates a new empty directory whose name is the last item specified in the pathname, in the specified drive. If active, the drive need not be specified. If the directory is to be created as a sub-directory of the working directory on the active drive, typing MD {directory name} at the DOS prompt or command prompt is sufficient.
Examples:
1. A:> MD ACCTSALARY
makes a SALARY directory in the: drive, under ACCT directory.
2. A:> MD C:> SALARY
Makes a salary directory in the C: drive, under root directory.
5.11 DELETING A DIRECTORY
You may want to delete or remove a directory to simplify your directory structure. DOS provides RD (Remove Directory) to delete a directory.
Example:
1. A:> RD ACCTSALARY
removes the SALARY sub-directory in ACCT directory.
NOTE: You cannot delete a directory if you are in it. Before you can delete a directory, you must type cd.. at the command prompt. At the same point of time, the directory to be deleted should be empty.

Copying files
To copy a file, DOS provides COPY’ command. When you usecopy’ command, you must use the following two parameters; the location and the name of the file you want to copy, or the source; and the location and the file name to which you want to copy the file or the target (destination). You separate the source and the destination or target with a space. The syntax of the `COPY’ command is
COPY {source} {destination} or,
COPY [drive:] [path] [filename] [drive:] [path] [filename]
i.e. the first set of drive, path and filename refers to the source file, and the second set of drive, path and filename
refers to the destination file.
(a) Copying Single File
To copy the DEBUG.EXE file from the DOS directory to the NOS
directory

Return to the root directory by typing the following command prompt: CD
Change to the DOS directory by typing the following commands at the DOS prompt: CD DOS
To copy the file DEBUG.EXE file from the DOS directory to the NOS, directory type the following at the command prompt: Copy c:dosdebug.exe c:nos and the following message appears: 1 file (s) copied Examples: 1. A:> copy a:letteroffice.doc letteroffice.bak makes a copy of the office.doc file in the current or working directory with a new name office.bak 2. A:> copy office.doc a:lettersnos.mem copy the file office.doc from the root directory to the sub-directory LETTER under root directory with a new name nos.mem. If the target drive is not specified, the copied file will reside in the disk mounted on the active drive. 5.13 USE OF WILDCARD CHARACTERS If you want to carry out a task for a group of files whose names have something in common, you can use wildcard characters to specify groups of files. DOS recognize two wildcard characters: asterisk () represents one or more characters that a group of files has in common; and the question mark (?) represents a single character that a group of files has in common. You can use wildcards to replace all or part of a file’s name or its extension. The following table shows examples of wildcards: Wildcard What it Represents Example *.TXT All files with a .TXT extension JULY.TXT LETTER.TXT REPORT. All files named REPORT with any REPORT.TXT extension REPORT.LET REPORT.WRI M*.* All files beginning with letter M MEMO.TXT regardless of their extension MARCH.XLI ???.* All files having 3 letter names, SUN.BMP with any or no extension WIN.LET You can include the wildcard in the command. Use of wildcard characters in COPY command 1. A:>COPY letters*.COB B: It means, copy all files with extension *.COB from the directory LETTERS under the ROOT directory to the working or ROOT directory of the `B’ drive.
A:> COPY B:COMPANYOPEL.* The command is to copy all files with primary name OPEL (irrespective extension) in the directory COMPANY under ROOT of the drive B’ into the current working directory of the disk mounted inA’ drive. Incase of one drive, the system will ask for the source and target drive. The command, 3.A:>COPY C:.

copies all files of the ROOT directory of the ‘C’ drive into the working directory of the ‘A’ drive.

A:> COPY LETTE?.* B: copies all files with primary name consisting of 6 characters in total and LETTE as the first five characters (irrespective of extension name) into drive `B’.
A:> COPY B:?.DOC copies all files having a primary name of one character with an extension .DOC from ROOT directory of ‘B’ to the ROOT directory of `A’ drive. 5.14 RENAMING FILES To rename a file, DOS provides REN command. The REN command stands for “Rename”. When you use the REN command, you must include two parameters. The first is the file you want to rename, and the second is the new name for the file. You separate the two names with a space. The REN command follows this pattern: REN oldname newname Example: REN NOS.DOC NOS.MEM Rename the old filename NOS.DOC to a new filename NOS.MEM.

Deleting files
This section explains how to delete or remove a file that is no longer required in the disk. DOS provides DEL command, which means to delete.
Syntax : DEL {drive:} {path} {filename}
Example:
1. DEL DOSEDIT.HLP
delete the EDIT.HLP from the DOS directory under ROOT directory.
5.16 PRINTING A FILE
The PRINT’ command of DOS works more or less likeTYPE’ com
mand, but at the same time, it enables the content of a text file
to be printed on a paper.
Syntax:
A:> PRINT [drive:] {path} {filename}
Example:
A:> PRINT AIAETLETTERAIAET.LET

In-text questions 1
1. The startup routine runs, when machine boots up is known as

POST
BOOT up
Operating Routine
I/O operation

2. Operating system is also known as:

database
System software
Hardware
Printer

3. What is the maximum length allowed for primary name of a computer file under DOS?

8
12
3
None of the above

4. Which of the following could be a valid DOS file specification?

NOSFILE.POST
NOSFILE.P.OST
NOSFILE.DOC
NOST.FILEDOC

5. How many characters form a secondary name for a file?

8
12
3
None of the above

6. What is the name given to something that the computer will automatically use unless you tell it otherwise?

a specification
a wildcard
a default
a rule

7. As per symbolic notation of DOS, which of the following indicates the ROOT directory
(a)*
(b) >
(c) /
(d) None of the above

8. In wildcard specification `?’ is used as replacement for

9. With DOS, you may use the *’ and?’:

When changing the default settings
To represent unspecified characters in a filename
Instead of wildcard characters
In the extension but not in the drive name or the file name

10. DOS system file consists of

IBMBIO.COM, IBMDOS.COM, COMMAND.COM
COMMAND.COM, IBMBIO.COM, FORMAT.COM
SYS.COM,IBMBIO.COM,IBMDOS.COM
None of the above

11. The batch file uses the extension

.BAT
.DOC
.PRG
.DOS

12. To display the list of all the file of the disk you would type

DIR
COPY
DIR FILES
DIR AUTOEXEC.BAT

13. State whether the following questions are True(T) or False(F).

Command.Com is hidden file.
Primary name of a file can be of 10 characters.
The command MKDIR and MD performs the same task.
Under DOS .EXE is not an executable file.
DIR command is used to see the content of a specific file.

What you have learnt
In this lesson you were introduced to one of the most popular desktop operating system and its working environment. It explained the directory structure, file naming conventions. It also talked in great length about the file management in terms of COPY, DEL, and MOVE. Here you learned the steps involved in loading of operating systems into computer.

Terminal questions

Explain in brief what do you understand by Operating system.
Explain the process involved in loading of Operating System.

Feedback to in-text questions 1

2.b3.a,4.b,5.b,6.c,7.d,8.a,9.b,10.a,11.a,12.a,13. F,F,T,F,F

Limitations and evolutions of computer

Computer 11 Notes — Sun, 08 Apr 2012 05:41:42 +0000

Chapter 1
Limitations and evolutions of computer

Characteristics / Features of Computer

Speed (Processing)
Accuracy
Reliability
Storage Capacity
Word Length
Diligence
Versatile
Automatic
Electronic
Non-intelligent

Application Areas of Computer

Education
Communication
Business
Transportation
Banking
Health, Medicine, hospital
Security, military
Industry
Scientific research
Entertainment
Weather Forecasting
Desktop Publishing
Designing
Satellite Controlling
Aviation

Applications of Computer

Storing and maintain records
Helping deaf and dump people to communicate
Controlling the process of production in industries
Translating text from one language to another
Transforming information from one place to another
Playing games at homes
Logging archaeological findings
Designing and launching missiles, rockets, etc.

Advantages of Computer

They are fast device which helps us save our time and money
It is an automatic device
It is a diligence device
It is versatile i.e. it can be used in many different fields with minimum changes to it
It is always accurate and reliable then humans
It has a vast space for data storage
It can be used for communication purpose

Disadvantages of Computer

It is machine dependent
Repair and maintenance is required frequently
Skilled manpower is must to work in computers
It is still unaffordable to every household due to its very high cost
It has been widely used for cyber crimes
Computer users become completely dependent upon computers and working without them will be very difficult
With the overwhelming use of computer, unemployment problems might be created in lack of proper policies

History of Computer (Some important ones are only discussed over here)
ABACUS

A Chinese abacus
The abacus, also called a counting frame, is a calculating tool used primarily in parts of Asia for performing arithmetic processes. Today, abaci are often constructed as a bamboo frame with beads sliding on wires, but originally they were beans or stones moved in grooves in sand or on tablets of wood, stone, or metal. The abacus was in use centuries before the adoption of the written modern numeral system and is still widely used by merchants, traders and clerks in Asia, Africa, and elsewhere. The user of an abacus is called an abacist.

EDVAC

The EDVAC is the successor of the ENIAC. Made by the same designers: Mauchly and Eckert.

design by Mauchly and Eckert
This computer was called by acronym EDVAC (Electronic Discrete Variable Automatic Computer) and its public presentation was carried through in 1947
This machine should be able to hold any program in memory that was fed to it. This would be possible because EDVAC was going to have more internal memory than any other computing device at that time. In other words, it was a multipurpose computer.

The idea being that given a tube of mercury, an electronic pulse could be bounced back and forth to be retrieved at will–another two state device for storing 0s and 1s. This on/off switch ability for the memory was required because EDVAC was to use binary rather than decimal numbers, thus simplifying the construction of the arithmetic units.
Source

Charles Babbage (1791 – 1871)

Babbage was a British mathematician, an original and innovative thinker and a pioneer of computing.

Charles Babbage was born on 26 December 1791, probably in London, the son of a banker. He was often unwell as a child and was educated mainly at home. By the time he went to Cambridge University in 1810 he was very interested in mathematics.
After graduation Babbage was hired by the Royal Institution to lecture on calculus. Within two years he had been elected a member of the Royal Society and, with his Cambridge friends, was instrumental in setting up the Astronomical Society in 1820, the first to challenge the dominance of the Royal Society. From 1828 to 1839, Babbage was Lucasian Professor of Mathematics at Cambridge.
The 1820s saw Babbage work on his ‘Difference Engine’, a machine which could perform mathematical calculations. A six-wheeled model was initially constructed and demonstrated to a number of audiences. He then developed plans for a bigger, better, machine – Difference Engine 2. He also worked on another invention, the more complex Analytical Engine, a revolutionary device on which his fame as a computer pioneer now largely rests. It was intended to be able to perform any arithmetical calculation using punched cards that would deliver the instructions, as well as a memory unit to store numbers and many other fundamental components of today’s computers. The remarkable British mathematician Ada Lovelace completed a program for the Analytical Engine but neither it, nor Difference Engine 2, were finished in Babbage’s lifetime.
Babbage also worked in the fields of philosophy and code-breaking, as well as campaigning for reform in British science. He died at his home in London on 18 October 1871.

Joseph Marie Jacquard

Joseph Marie Charles (called or nicknamed) Jacquard (7 July 1752 (Lyon, France) – 7 August 1834 (Oullins, France)) played an important role in the development of the earliest programmable loom (the “Jacquard loom“), which in turn played an important role in the development of other programmable machines, such as computers.
The Jacquard loom is a mechanical loom that has holes punched in pasteboard, each row of which corresponds to one row of the design. Multiple rows of holes are punched on each card and the many cards that compose the design of the textile are strung together in order.

Programming Concept | Computer Science | HSEB Notes

Computer 11 Notes — Sun, 08 Apr 2012 05:41:42 +0000

Detailed notes to follow:

- Types of programming language

1. Low level language

Machine Language (1GL)
Assembly Language (2GL)

2. High level language

Procedural-Oriented Language (3GL)
Problem-Oriented (Fourth Generation) Language (4GL)
Natural (Fifth Generation) Language (5GL)

- Language translator

Assembler
Compiler
Interpreter

- Syntax and semetics

Syntax Error
Sematic Error
Run-Time Error

- Flowchart

System Flowchart
Program Flowchart

Computer Organization

Computer 11 Notes — Sun, 08 Apr 2012 05:41:42 +0000

(Inside Computer System)

Introduction to computer organization

In the previous lesson we discussed about the evolution of computer. In this lesson we will provide you with an overview of the basic design of a computer. You will know how different parts of a computer are organized and how various operations are performed between different parts to do a specific task. As you know from the previous lesson the internal architecture of computer may differ from system to system, but the basic organization remains the same for all computer systems.

Objectives

At the end of the lesson you will be able to:

Understand basic organization of computer system
Understand the meaning of Arithmetic Logical Unit, Control Unit and Central Processing Unit
Differentiate between bit , byte and a word
Define computer memory
Differentiate between primary memory and secondary memory
Differentiate between primary storage and secondary storage units
Differentiate between input devices and output devices

Basic computer operations

A computer as shown in Fig. 2.1 performs basically five major operations or functions irrespective of their size and make. These are 1) it accepts data or instructions by way of input, 2) it stores data, 3) it can process data as required by the user, 4) it gives results in the form of output, and 5) it controls all operations inside a computer. We discuss below each of these operations.

1. Input: This is the process of entering data and programs in to the computer system. You should know that computer is an electronic machine like any other machine which takes as inputs raw data and performs some processing giving out processed data. Therefore, the input unit takes data from us to the computer in an organized manner for processing.

2. Storage: The process of saving data and instructions permanently is known as storage. Data has to be fed into the system before the actual processing starts. It is because the processing speed of Central Processing Unit (CPU) is so fast that the data has to be provided to CPU with the same speed. Therefore the data is first stored in the storage unit for faster access and processing. This storage unit or the primary storage of the computer system is designed to do the above functionality. It provides space for storing data and instructions.

The storage unit performs the following major functions:

All data and instructions are stored here before and after processing.
Intermediate results of processing are also stored here.

3. Processing: The task of performing operations like arithmetic and logical operations is called processing. The Central Processing Unit (CPU) takes data and instructions from the storage unit and makes all sorts of calculations based on the instructions given and the type of data provided. It is then sent back to the storage unit.

4. Output: This is the process of producing results from the data for getting useful information. Similarly the output produced by the computer after processing must also be kept somewhere inside the computer before being given to you in human readable form. Again the output is also stored inside the computer for further processing.

5. Control: The manner how instructions are executed and the above operations are performed. Controlling of all operations like input, processing and output are performed by control unit. It takes care of step by step processing of all operations in side the computer.

Functional units

In order to carry out the operations mentioned in the previous section the computer allocates the task between its various functional units. The computer system is divided into three separate units for its operation.
They are:

Arithmetic logical unit
Control unit
Central processing unit

Arithmetic logical unit (ALU)

After you enter data through the input device it is stored in the primary storage unit. The actual processing of the data and instruction are performed by Arithmetic Logical Unit. The major operations performed by the ALU are addition, subtraction, multiplication, division, logic and comparison. Data is transferred to ALU from storage unit when required. After processing the output is returned back to storage unit for further processing or getting stored.

Control unit (CU)

The next component of computer is the Control Unit, which acts like the supervisor seeing that things are done in proper fashion. The control unit determines the sequence in which computer programs and instructions are executed. Things like processing of programs stored in the main memory, interpretation of the instructions and issuing of signals for other units of the computer to execute them. It also acts as a switch board operator when several users access the computer simultaneously. Thereby it coordinates the activities of computer’s peripheral equipment as they perform the input and output. Therefore it is the manager of all operations mentioned in the previous section..

Central processing unit (CPU)

The ALU and the CU of a computer system are jointly known as the central processing unit. You may call CPU as the brain of any computer system. It is just like brain that takes all major decisions, makes all sorts of calculations and directs different parts of the computer functions by activating and controlling the operations.

Fig. 2.2: Computer Architecture

Personal computer configuration

Now let us identify the physical components that make the computer work. These are:

Central Processing Unit (CPU)
Computer Memory (RAM and ROM)
Data bus
Ports
Motherboard
Hard disk
Output Devices
Input Devices

All these components are inter-connected for the personal computer to work.

In-text questions 1

1. What are the five basic operations performed by the computer?

2. Define ALU, CU and CPU.

3. Choose the correct answer:

1. The task of performing arithmetic and logical operations is called**

ALU
Editing
Storage
Output

2. The ALU and CU jointly known as

RAM
ROM
CPU
None of the above

3. The process of producing results from the data for getting useful information

Output
Input
Processing
Storage

Memory system in a computer

There are two kinds of computer memory: primary and secondary. Primary memory is accessible directly by the processing unit. RAM is an example of primary memory. As soon as the computer is switched off the contents of the primary memory is lost. You can store and retrieve data much faster with primary memory compared to secondary memory. Secondary memory such as floppy disks, magnetic disk, etc., is located outside the computer. Primary memory is more expensive than secondary memory. Because of this the size of primary memory is less than that of secondary memory. We will discuss about secondary memory later on.

Computer memory is used to store two things: i) instructions to execute a program and ii) data. When the computer is doing any job, the data that have to be processed are stored in the primary memory. This data may come from an input device like keyboard or from a secondary storage device like a floppy disk.

As program or the set of instructions is kept in primary memory, the computer is able to follow instantly the set of instructions. For example, when you book ticket from railway reservation counter, the computer has to follow the same steps: take the request, check the availability of seats, calculate fare, wait for money to be paid, store the reservation and get the ticket printed out. The programme containing these steps is kept in memory of the computer and is followed for each request.

But inside the computer, the steps followed are quite different from what we see on the monitor or screen. In computer’s memory both programs and data are stored in the binary form. You have already been introduced with decimal number system, that is the numbers 1 to 9 and 0. The binary system has only two values 0 and 1. These are called bits. As human beings we all understand decimal system but the computer can only understand binary system. It is because a large number of integrated circuits inside the computer can be considered as switches, which can be made ON, or OFF. If a switch is ON it is considered 1 and if it is OFF it is 0. A number of switches in different states will give you a message like this: 110101….10. So the computer takes input in the form of 0 and 1 and gives output in the form 0 and 1 only. Is it not absurd if the computer gives outputs as 0’s & 1’s only? But you do not have to worry about. Every number in binary system can be converted to decimal system and vice versa; for example, 1010 meaning decimal 10. Therefore it is the computer that takes information or data in decimal form from you, convert it in to binary form, process it producing output in binary form and again convert the output to decimal form.

The primary memory as you know in the computer is in the form of IC’s (Integrated Circuits). These circuits are called Random Access Memory (RAM). Each of RAM’s locations stores one byte of information. (One byte is equal to 8 bits). A bit is an acronym for binary digit, which stands for one binary piece of information. This can be either 0 or 1. You will know more about RAM later. The Primary or internal storage section is made up of several small storage locations (ICs) called cells. Each of these cells can store a fixed number of bits called word length.

Each cell has a unique number assigned to it called the address of the cell and it is used to identify the cells. The address starts at 0 and goes up to (N-1). You should know that the memory is like a large cabinet containing as many drawers as there are addresses on memory. Each drawer contains a word and the address is written on outside of the drawer.

Capacity of primary memory

You know that each cell of memory contains one character or 1 byte of data. So the capacity is defined in terms of byte or words. Thus 64 kilobyte (KB) memory is capable of storing 64 ´ 1024 = 32,768 bytes. (1 kilobyte is 1024 bytes). A memory size ranges from few kilobytes in small systems to several thousand kilobytes in large mainframe and super computer. In your personal computer you will find memory capacity in the range of 64 KB, 4 MB, 8 MB and even 16 MB (MB = Million bytes).

The following terms related to memory of a computer are discussed below:

1. Random Access Memory (RAM): The primary storage is referred to as random access memory (RAM) because it is possible to randomly select and use any location of the memory directly store and retrieve data. It takes same time to any address of the memory as the first address. It is also called read/write memory. The storage of data and instructions inside the primary storage is temporary. It disappears from RAM as soon as the power to the computer is switched off. The memories, which loose their content on failure of power supply, are known as volatile memories .So now we can say that RAM is volatile memory.

2. Read Only Memory (ROM): There is another memory in computer, which is called Read Only Memory (ROM). Again it is the ICs inside the PC that form the ROM. The storage of program and data in the ROM is permanent. The ROM stores some standard processing programs supplied by the manufacturers to operate the personal computer. The ROM can only be read by the CPU but it cannot be changed. The basic input/output program is stored in the ROM that examines and initializes various equipment attached to the PC when the switch is made ON. The memories, which do not loose their content on failure of power supply, are known as non-volatile memories. ROM is non-volatile memory.

3. PROM: There is another type of primary memory in computer, which is called Programmable Read Only Memory (PROM). You know that it is not possible to modify or erase programs stored in ROM, but
it is possible for you to store your program in PROM chip. Once the programmes are written it cannot be changed and remain intact even if power is switched off. Therefore programs or instructions written in PROM or ROM cannot be erased or changed.

4. EPROM: This stands for Erasable Programmable Read Only Memory, which over come the problem of PROM & ROM. EPROM chip can be programmed time and again by erasing the information stored earlier in it. Information stored in EPROM exposing the chip for some time ultraviolet light and it erases chip is reprogrammed using a special programming facility. When the EPROM is in use information can only be read.

5. Cache Memory: The speed of CPU is extremely high compared to the access time of main memory. Therefore the performance of CPU decreases due to the slow speed of main memory. To decrease the mismatch in operating speed, a small memory chip is attached between CPU and Main memory whose access time is very close to the processing speed of CPU. It is called cache memory. Cache memories are accessed much faster than conventional RAM. It is used to store programs or data currently being executed or temporary data frequently used by the CPU. So each memory makes main memory to be faster and larger than it really is. It is also very expensive to have bigger size of cache memory and its size is normally kept small.

6. Registers: The CPU processes data and instructions with high speed, there is also movement of data between various units of computer. It is necessary to transfer the processed data with high speed. So the computer uses a number of special memory units called registers. They are not part of the main memory but they store data or information temporarily and pass it on as directed by the control unit.

In-text questions 2

1. Distinguish between bit and byte.

2. Define volatile and non-volatile memory.

3. Write True or False:

There are two kinds of computer memory primary and secondary.
The computer takes inputs in the form of 0 and 1.
The storage of program and data in the RAM is permanent.
PROM is secondary memory.
The memories which do not loose their content on failure of power supply are known as non-volatile memories.

Secondary storage

You are now clear that the operating speed of primary memory or main memory should be as fast as possible to cope up with the CPU speed. These high-speed storage devices are very expensive and hence the cost per bit of storage is also very high. Again the storage capacity of the main memory is also very limited. Often it is necessary to store hundreds of millions of bytes of data for the CPU to process. Therefore additional memory is required in all the computer systems. This memory is called auxiliary memory or secondary storage.

In this type of memory the cost per bit of storage is low. However, the operating speed is slower than that of the primary storage. Huge volume of data are stored here on permanent basis and transferred to the primary storage as and when required. Most widely used secondary storage devices are magnetic tapes and magnetic disk.

1. Magnetic tape: Magnetic tapes are used for large computers like mainframe computers where large volume of data is stored for a longer time. In PC also you can use tapes in the form of cassettes. The cost of storing data in tapes is inexpensive. Tapes consist of magnetic materials that store data permanently. It can be 12.5 mm to 25 mm wide plastic film-type and 500 meter to 1200 meter long which is coated with magnetic material. The deck is connected to the central processor and information is fed into or read from the tape through the processor. It similar to cassette tape recorder.

Advantages of magnetic tape:

Compact: A 10-inch diameter reel of tape is 2400 feet long and is able to hold 800, 1600 or 6250 characters in each inch of its length. The maximum capacity of such tape is 180 million characters. Thus data are stored much more compactly on tape.

Economical:
The cost of storing characters is very less as compared to other storage devices.

Fast: Copying of data is easier and fast.

Long term Storage and Re-usability: Magnetic tapes can be used for long term storage and a tape can be used repeatedly with out loss of data.

2. Magnetic Disk: You might have seen the gramophone record, which is circular like a disk and coated with magnetic material. Magnetic disks used in computer are made on the same principle. It rotates with very high speed inside the computer drive. Data is stored on both the surface of the disk. Magnetic disks are most popular for direct access storage device. Each disk consists of a number of invisible concentric circles called tracks. Information is recorded on tracks of a disk surface in the form of tiny magnetic spots. The presence of a magnetic spot represents one bit and its absence represents zero bit. The information stored in a disk can be read many times without affecting the stored data. So the reading operation is non-destructive. But if you want to write a new data, then the existing data is erased from the disk and new data is recorded.

3. Floppy Disk: It is similar to magnetic disk discussed above. They are 5.25 inch or 3.5 inch in diameter. They come in single or double density and recorded on one or both surface of the diskette. The capacity of a 5.25-inch floppy is 1.2 mega bytes whereas for 3.5 inch floppy it is 1.44 mega bytes. It is cheaper than any other storage devices and is portable. The floppy is a low cost device particularly suitable for personal computer system.

4. Optical Disk:

With every new application and software there is greater demand for memory capacity. It is the necessity to store large volume of data that has led to the development of optical disk storage medium. Optical disks can be divided into the following categories:

Compact disk/ read only memory (CD-ROM): CD-ROM disks are made of reflective metals. CD-ROM is written during the process of manufacturing by high power laser beam. Here the storage density is very high, storage cost is very low and access time is relatively fast. Each disk is approximately 4 1/2 inches in diameter and can hold over 600 MB of data. As the CD-ROM can be read only we cannot write or make changes into the data contained in it.

Write once, read many (WORM): The inconvenience that we can not write any thing in to a CD-ROM is avoided in WORM. A WORM allows the user to write data permanently on to the disk. Once the data is written it can never be erased without physically damaging the disk. Here data can be recorded from keyboard, video scanner, OCR equipment and other devices. The advantage of WORM is that it can store vast amount of data amounting to gigabytes (109 bytes). Any document in a WORM can be accessed very fast, say less than 30 seconds.

Erasable optical disk: These are optical disks where data can be written, erased and re-written. This also applies a laser beam to write and re-write the data. These disks may be used as alternatives to traditional disks. Erasable optical disks are based on a technology known as magnetic optical(MO). To write a data bit on to the erasable optical disk the MO drive’s laser beam heats a tiny, precisely defined point on the disk’s surface and magnetizes it.

Input output device

A computer is only useful when it is able to communicate with the external environment. When you work with the computer you feed your data and instructions through some devices to the computer. These devices are called Input devices. Similarly computer after processing, gives output through other devices called output devices.

For a particular application one form of device is more desirable compared to others. We will discuss various types of I/O devices that are used for different types of applications. They are also known as peripheral devices because they surround the CPU and make a communication between computer and the outer world.

Input devices

Input devices are necessary to convert our information or data in to a form which can be understood by the computer. A good input device should provide timely, accurate and useful data to the main memory of the computer for processing followings are the most useful input devices.

1. Keyboard: – This is the standard input device attached to all computers. The layout of keyboard is just like the traditional typewriter of the type QWERTY. It also contains some extra command keys and function keys. It contains a total of 101 to 104 keys. A typical keyboard used in a computer is shown in Fig. 2.6. You have to press correct combination of keys to input data. The computer can recognize the electrical signals corresponding to the correct key combination and processing is done accordingly.

Fig. 2.6

2. Mouse: – Mouse is an input device that is used with your personal computer. It rolls on a small ball and has two or three buttons on the top. When you roll the mouse across a flat surface the screen censors the mouse in the direction of mouse movement. The cursor moves very fast with mouse giving you more freedom to work in any direction. It is easier and faster to move through a mouse.

3. Scanner: The keyboard can input only text through keys provided in it. If we want to input a picture the keyboard cannot do that. Scanner is an optical device that can input any graphical matter and display it back. The common optical scanner devices are Magnetic Ink Character Recognition (MICR), Optical Mark Reader (OMR) and Optical Character Reader (OCR).

Magnetic ink character recognition (MICR): This is widely used by banks to process large volumes of cheques and drafts. Cheques are put inside the MICR. As they enter the reading unit the cheques pass through the magnetic field which causes the read head to recognise the character of the cheques.

Optical mark reader (OMR): This technique is used when students have appeared in objective type tests and they had to mark their answer by darkening a square or circular space by pencil. These answer sheets are directly fed to a computer for grading where OMR is used.

Optical character recognition (OCR): This technique unites the direct reading of any printed character. Suppose you have a set of hand written characters on a piece of paper. You put it inside the scanner of the computer. This pattern is compared with a site of patterns stored inside the computer. Whichever pattern is matched is called a character read. Patterns that cannot be identified are rejected. OCRs are expensive though better the MICR.

Output devices

1. Visual display unit: The most popular input/output device is the Visual Display Unit (VDU). It is also called the monitor. A Keyboard is used to input data and Monitor is used to display the input data and to receive massages from the computer. A monitor has its own box which is separated from the main computer system and is connected to the computer by cable. In some systems it is compact with the system unit. It can be coloror monochrome.

2. Terminals: It is a very popular interactive input-output unit. It can be divided into two types: hard copy terminals and soft copy terminals. A hard copy terminal provides a printout on paper whereas soft copy terminals provide visual copy on monitor. A terminal when connected to a CPU sends instructions directly to the computer. Terminals are also classified as dumb terminals or intelligent terminals depending upon the work situation.

3. Printer: It is an important output device which can be used to get a printed copy of the processed text or result on paper. There are different types of printers that are designed for different types of applications. Depending on their speed and approach of printing, printers are classified as impact and non-impact printers. Impact printers use the familiar typewriter approach of hammering a typeface against the paper and inked
ribbon. Dot-matrix printers are of this type. Non-impact printers do not hit or impact a ribbon to print. They use electro-static chemicals and ink-jet technologies. Laser printers and Ink-jet printers are of this type. This type of printers can produce color printing and elaborate graphics.

In-text questions 3

1. Distinguish between impact and non-impact printers.

2. Define soft copy and hard copy terminals.

3. Write True or False:

Secondary memory is called Auxiliary memory.
The magnetic tapes and magnetic disk are primary memories.
A CD-ROM is read only memory.
Mouse is an output device.
Printer is an important output device.

What you have learnt

In this lesson we discussed five basic operations that a computer performs. These are input, storage, processing, output and control. A computer accepts data as input, stores it, processes it as the user requires and provides the output in a desired format. The storage unit of a computer is divided into two parts: primary storage and secondary storage. We have discussed the devices used for these two types of storage and their usefulness.

Terminal questions

What are the five basic operations performed by any computer system?
Draw a block diagram to illustrate the basic organization of computer system and explain the function of various units.
What is input device? How does it differ from output device?
Differentiate between RAM and ROM. Also distinguish between PROM and EPROM.
What is cache memory? How is it different from primary memory?
Write short notes on:

Control Unit
Random Access Memory (RAM)

Feedback to in-take questions

In-text questions 1

1. The five basic operations that a computer performs are input, storage, processing, output and control.

ALU: Arithmetic Logic Unit
CU: Control Unit
CPU: Central Processing Unit

3. 1,3,1

In-take questions 2

1. A bit is an acronym for binary digit, which stands for one binary piece of information. This can be either 0 or 1. A byte is equal to 8 bits.

2. The memories which are erased if there is a power failure are known as volatile memories. RAM is an example of volatile memory. The memories, which do not loose their content on failure of power supply, are known as non-volatile memories. ROM is non-volatile memory.

3. 1. T 2. T 3. F 4. F 5. T

In-take questions 3

1. Impact printers use the familiar typewriter approach of hammering a typeface against the paper and inked ribbon. Non-impact printers do not hit or impact a ribbon to print. They use electro-static chemicals and ink-jet technologies.

2. A hard copy terminal provides a printout on paper whereas soft copy terminals provide visual copy on monitor.

3. 1. T 2. F 3. T 4. F 5. T

An Introduction To Windows 95

Computer 11 Notes — Sun, 08 Apr 2012 05:41:42 +0000

Introduction to Windows-95

Windows 95 is the upgraded version of Windows 3.x series with lots of new features embedded into it. It is a complete paradigm shift from windows 3.x working environment.

It is the entry point to a 32-bit operating/computing environment with less set of hardware requirements. It has more compatibility with other software as compared to its previous version and provides easy installation. It also runs most of the Windows 3.x and Microsoft DOS programs. Windows 95 also provides flexibility to configure hardware, easy link to a network or setup a network, install and uninstall programs automatically. It also has lots of other useful features like easy Internet access, multitasking, and its most useful feature is long file names.

Objectives

At the end of this lesson you would be able to

Understand the difference between Windows 3.11 and Windows95.
Able to work on Windows95
Appreciate the uses of Long file name
Appreciate the new look and feel of Windows95.

Improved features of Windows 95

Graphical user interface:
As compared to Windows 3.x, Windows 95 provides user-friendlier interface to work on. Its improved graphical user interface makes learning and using Windows 95 more natural and easier for all types of users. It is more powerful, customizable and efficient.

Start button
Introduction of start button in Windows 95 made life much simpler while there is a need to access multiple programs. It is the gateway of accessing most of the functionality available in the computer loaded with Windows 95. Just click on the start button anytime to start any programs, open or find documents, change windows settings, get help, manage Files, maintain system, and much more.

Taskbar
As the name suggests, the Task bar provides information and access to the entire task that has been currently activated by Windows 95. Using this one can keep a track of what all programs have been activated and switched between them.

Windows explorer
Windows explorer is more or less acts as a File manager for Windows 95, but with lots of new features. It is more efficient, faster and user friendly as compared to File Manager of Windows 3.x.
Using explorer one can easily browse through all the drives and network resources available and manage files.

Right mouse button
Clicking on the right mouse button activates a pop-up menu in any programs so as to help in completing a task efficiently.

Long file names
As the Microsoft DOS convention follows, non-of the file used in DOS environment should be more than 8 characters of primary name and optional secondary name (extension) of three characters. However Windows 95 has broken this barrier. Windows 95 supports long file names, maximum of 255 characters. It also allowed space to be used in between file name. This helps to make files and folders (directory/subdirectory) easier to organize and find.

Shortcuts
As the name suggests, shortcuts are the shortest way to access programs, files and other resources in Windows 95. Instead of going through the structural process of accessing a program, one can create “shortcuts” to access them. It creates links for easy access to files, programs, folders, and more.

Multitasking
Multitasking allows the user to activate and accomplish more than one task at a time. For example, work on a document file in WORD programs, while copying file from other computer available in the network. With Windows 95, 32-bit computing environment, the user can do more than one task a time.

Easy internet access
One of the most useful and entirely new features is Windows 95 easy access to Internet. It provides built-in Internet functionality to setup link and access Internet with less amount of Hardware and Software requirement. It also provides connectivity software from Microsoft network (MSN), CompuServe, and America Online.

It also improves the efficiency of working on Internet with applications that support the latest Internet technologies, such as ActiveX, Java, and streaming audio and video.

Software Compatibility
Windows 95 provides complete backward compatibility. It is easily compatible with applications developed for Microsoft DOS and Windows 3.x environment. It also supports the latest 32-bit technology. Most of the latest software packages are now built on Windows 95 operating environment.

Great gaming platform
Windows 95 support rich graphics, high quality audio and video. It also requires all most no editing of Config.sys files so as to support these technologies. All this is possible because of Windows 95 compatibility with latest and hottest technologies like Plug and Play, AutoPlay, and built-in support for MIDI and digital and surrounds video.

Hardware compatibility
Windows 95 provides greater Hardware compatibility as compare to any other operating environment. It has flexibility of supporting hardware from different vendors. Its Plug and Play functionality allows to insert the hardware card into the computer and when the computer is turned on Windows 95 automatically recognizes and sets up the hardware.

Find utility
Find Utility of Windows 95 allows you to do searches by partial name, last modified date, or full text. In addition, you can save, rename, or view files from within the result pane, just like you can from Windows Explorer.

Help
Windows 95 provides online help to accomplish a task. If the user is not sure how to perform a task, Windows 95 Help will provide structured process how to accomplish the task. Simply right-click on any object in the user interface (icons) and you’ll get relevant descriptions about that object.

1. System requirements

CPU	Recommended 486/25 MHz-based system or more
Memory	Recommended a minimum of 8-MB memory (RAM).
Hard disk space	Available free hard disk space of 40-45 MB.
Display	VGA or higher-resolution display.
Operating system	Microsoft DOS
Peripheral/miscellaneous	Compatible pointing device

2. Windows desktop items

My computer	Provides direct access to local drives, printers, control panel, and the Dial-up network utility.
Network neighborhood	Access to shared resources on the machine and computers on local and wide area network.
Recycle bin	Provides drag and drop facilities, deletion of file from folders in the machine and provides a second chance to recover files deleted from the hard disk.
Inbox or Microsoft Outlook	Universal in-box for all mail sources including faxes, mail, exchange, and others.

Start button and task bar

Windows now features the Start button and Taskbar at the bottom of the screen. This bar contains the Start button. Using this button, a program can be quickly started or file can be searched for. Quick help on how to use windows can also be obtained from this task bar.

Click on the start to activate the pop-up menu so as to open a program, find a file or folders (directory or sub-directory), and change the settings for Windows95, Run a program or shut down the computer and also to get help on windows.

If you have opened more than one program or windows, you can switch between them. All the opened windows or program appears on the Start or the Task bar as a minimized icons. Click on the desired icon to open the designated program. Similarly if you don’t need a windows too frequently, click on the minimized button of the windows. This will send the activated window as small icon to the task bar.

1. Steps to start a program

Click on the Start button, and then point to Programs option.
Select the program you want to run. If the program you want is not on the menu, point to the folder that contains the program.
Click on the program icon or menu.

Once the selected program starts, a small icon appears on the taskbar. If you have opened more than one program, click on the required program icon on the taskbar to make it currently activated program.

If the desired program is not available on the program menu or one of its submenus, point to Find on the Start menu, and then click Files Or Folders where the program resides. You can also use the Find dialog box to locate the program file.

2. Steps to open a recently used document

Click on the start button
Select/point to Documents option.
Select the document you want to open, by clicking on it

Note:
All programs are not capable of adding files to Document menu. So if the desired document to be opened is not listed or available in Document Menu, click on the Start button, and then select the Find option. Select/click “files Or folders” option, and then use the Find dialog box to locate the file.

My computer

It allows looking at a glance to all the resource available on the machine such as floppy drive, CD-ROM drive, Hard Disk etc. If you have network drives mapped as local drives they will also show up here. Double clicking on a drive in the top level of my computer will open another window containing the main folders on the select drive. Double clicking on any of the folders in the drive window will open another window showing the contents of the folder.

Double clicking on either the control panel folder or the Printers folders in My Computer windows will activate the respective windows for Control panel or Printers. Using this you can manipulate the settings for your Computer or Printer the same way that you were accessing them from the start menu.

My Computer is the quickest way of accessing all the resources available on the computer. Even this can be used to copy, move, delete files among or between floppy and hard disk or network drives.

My Computer also provides the tools to change the settings of the available resources. Select the media such as floppy disk, hard disk drive you want to change the settings and right click on it. This will activate a Pop-Up menu. Now select the Properties option from the pop-up menu. This action will display the property windows with three options: General, Tools and Sharing. Using these three options you can change the properties of the selected media.

Windows explorer

As the name suggests, Windows Explorer let you explore the contents of your computer and do file management. It is the improved version of file Manager in Windows 3.1 or 3.11.

To activate Windows explorer, click on the start button on the task Bar and select programs option. This will activate another Pop-Up menu. Now select Windows Explorer option.

Windows Explorer displays on the left-hand side of the screen, all the folders on your computer in a hierarchical order. On the right hand side of the screen, it displays all the files and folders in each selected folder.

Windows Explorer is especially useful for copying and moving files. You can open the folder that contains the file you want to move or copy, and then drag it to the folder you want to put it in.

Steps to copy a file or folder

Go to My computer or Windows explorer
Select the file you want to copy by clicking on it.
Go to edit menu and select/click Copy option.
Open the folder or disk drive where you want to copy.
Again go to edit menu and select/click Paste option.

Steps to move a file or folder

Go to My computer or Windows explorer
Select the file you want to move by clicking on it.
Go to edit menu and select/click cut option.
Open the folder or disk drive where you want to move.
Again go to edit menu and select/click Paste option.

Steps to delete a file or folder

Go to My computer or Windows explorer
Select the file or folder you want to delete by clicking on it.
Go to file menu and select/click delete option.

Note:

Files or folder deleted are stored in the Recycle Bin until the Recycle Bin is emptied. Files or folders can also be deleted by dragging file or folder icons onto the Recycle Bin icon. If SHIFT key is pressed while dragging, the item will be deleted permanently from the computer without being stored in the Recycle Bin.
To select more than one file or folder to copy, while pressing the CTRL key, click the items you want to select.

Steps to copy a file to a floppy disk

Insert the disk in the floppy disk drive.
Go to My computer or Windows explorer
Select the file you want to copy, by clicking on the file.
Go to file menu, point to “send to” option, and then select the drive you want to copy the file to.

Steps to create a new folder

Go to My computer or Windows explorer; open the folder in which you want to create a new folder by double clicking on it.
Go to the file menu, point to New, and then click on the “folder” option.
The new folder appears with a temporary name.
Type a name for the new folder, and then press enter.

Steps to change the name of a file or folder

Go to My computer or Windows explorer
Click on the file or folder you want to rename.
Go to the file menu, and select/click “rename” option.
Type a new name for the file or Folder, and then press enter.

Note :
As Windows 95 supports long file name, a filename can be up to 255 characters, including spaces. However, it cannot contain any of the following characters:

/ : * ? ” < > |

Network neighborhood

A Network is a group of Computers connected to each other to share available resources such as storage and printers. Network neighborhood takes the ability of My Computer and extends them one step further, by giving you with the ability to view all of the Computers connected in workgroup or network, and see what drives or Printers may be available for use. If you double click on one of the Computers, any resources that Computer shares with others in the workgroup like- drives, directories or printers will be listed

When connected to a network, the Network Neighborhood icon appears on the desktop. To browse through the computers in the workgroup and the computers on the entire network, double click on the icon Network Neighborhood.

Recycle bin

The files deleted by you are put in the Recycle Bin, a holding place for files that are no longer needed. There you can also drag and drop files for quick deleting. They are, however, not actually removed from the hard disk until the user “empty” the recycle bin.

It is a safety feature, built in to protect you against the possibility of deleting something you should not have.

Find

Using Windows 95 it is easy to locate files and folders on the computer. One way is to browse through folders in My Computer. But if you want to find something quickly, you can use the find command on the start menu.

Click on the start button and select “find” option. Now select the option "files or folders". This will activate the find dialog box. In the find dialog box, type the name of the file or folder you are looking for, and then click find Now. You can also use wildcard character to find files

Work with programs

Windows 95 provides higher level of flexibility in terms of installing and removing programs.

To install a program from a floppy disk or CD-ROM
Select control Panel from the Settings option of Start Menu
Double Click on the add/remove programs icon.

Follow the instructions on your screen.

To install a program from a network

Click here to open the add/remove programs dialog box.
If the Install/Uninstall tab is selected, and your computer is already connected to a network, click Install button, and then click Next. Follow the instructions on your screen.

Note:
If you do not have a Network Install tab in the Add/Remove Programs dialog box, this feature has not been enabled on your computer, your network, or both. See your system administrator.

If you are not already connected to the shared folder you want to install from, you must connect to it by using My Computer or Windows Explorer, or type the path to it in the text box.

To remove a program from your computer

Select Control Panel from the Settings option of Start Menu
Double Click on the add/remove programs icon.
Follow the instructions on your screen.

Note:
Only programs that were designed for Windows 95 can be removed by using add/remove programs. For all other programs, check the program’s documentation to determine which files should be removed.

Microsoft-DOS windows

Windows 95 provides the flexibility of executing most of the DOS commands or DOS based program without going out of Windows 95 GUI. To use DOS prompt:

Click the start button, and then point to Programs.
Click/Select MS-DOS prompt.

Tips

To view the toolbar, click the MS-DOS icon in the title bar, and then click Toolbar.
To switch between a full screen and a window, press alt + enter.
To quit MS-DOS, click or type Exit at the command prompt.

Change windows settings

Windows 95 provides tools to change the look and feel of the desktop window. Using these tools you can change the desktop background, wallpaper and lots of other settings according to your choice.

To activate these tools, right click on the windows. This will display a menu now select the properties option.

You can also activate these tools from Control panel by selecting the display icon.

Desktop background

To change the background of the desktop

Right Click on the Desktop to view the Display properties.
In the Pattern or Wallpaper list, click the pattern or wallpaper you want to use.

Tips

To cover the entire screen with wallpaper image, click Tile.
To center a wallpaper image, click Center.
Patterns and wallpaper can be used simultaneously. However, you will not be able to see the pattern, if Title is selected.

Similarly all other option such as appearance, screen saver and settings can be used. Using the settings option, one can select the number of colors, pixel type and display adapter for the system.

Shut down the computer

Click the start button, click the shut down button, and then select the option Shut down the computer and click on the yes button.

Important

Do not turn off your computer until the “You can now safely turn off your computer” message appears.

In-text questions 1
Choose the best answer for the following questions.
1. Which of the following is introduced exclusively in Windows95?

Control panel
File manager
Start button
None of the above

2. What is the Windows 3.x series equivalent to Windows Explorer in Windows95?

Program manager
File manager
Print manager
None of the above

3. Answer whether the following statement is True (T) or False (F).

Windows 95 supports file name of 255 characters including space in between.
Windows 95 does not support Microsoft DOS based application.
Windows 95 is a application software.
In Windows 95 desktop icons can be created, but can not be deleted.

4. Fill in the blanks

Inbox in Windows 95 is used for ______________________.
GUI stands for ________________________.

What you have learnt

This lesson introduced you to one of the most popular and widely used GUI operating system in desktop environment. In the beginning it discussed what is GUI and its usefulness. It explained the new features of Windows95 and hardware requirement for installation. You also learned about various Windows 95 icons and their usability. Here we discussed how to do file management in Windows 95, and also we learned how to change look and feel of Windows 95 desktop according to user requirement.

Terminal questions

Briefly explain, how Windows95 is different from Windows 3.x series.
Explain what do you understand by multitasking?
What is the minimum hardware requirement for installing Windows95 software?
What is the purpose of recycle bin?
Explain the steps involved to shut down Windows95.

In-text questions 1

1. 3

2. 2

True
False
False
False

Getting e-mail
Graphical User Interface.

Bus Architecture

Computer 11 Notes — Sun, 08 Apr 2012 05:41:42 +0000

Bus is a group of wires that connects different components of the computer. It is used for transmitting data, control signal and memory address from one component to another. A bus can be 8 bit, 16 bit, 32 bit and 64 bit. A 32 bit bus can transmit 32 bit information at a time. A bus can be internal or external.

Types of bus:

1) Data bus
Data bus carries data from on component to another. It is uni-directional for input and output devices and bi-directional for memory and CPU.

2) Control bus
Control bus carries control signal. CU of CPU uses control signal for controlling all the components. It is uni-directional from CPU to all other components.

3) Address bus
Address bus carries memory address. A memory address is a numerical value used for identifying a memory location. Computer performs all its task through the memory address. CU of CPU sends memory address to all the components. So, address bus is also uni-directional from CPU to all other components.