CLASS 7 COMPUTER SCIENCE 2021-22

Click for->Computer notes Ch. 3 to 5 R/5 (Posted on 28/08/2021) Chapter 5 QBasic: Graphics and sounds TOPICS TO BE COVERED: 1. QBasic Graphics 2. PSET Command  3. Line Command 4. Paint Command 5. Sound Command Main teaching: QBasic Graphics QBasic is not graphically very capable but many good programs can be created with it. Commands like PSET, CIRCLE, LINE, etc., are used to draw graphics in QBasic. Functions Screen will let you set how it will be used. Text Graphics, both, and the Size of the surface you are working with. Screen 0 .. means Text Only. Screen 12 .. means 64 X 480 X 16 Colors & Text. PSET The PSET command lets the programmer display pixels on the screen. Before you type the command in, you must make sure that a SCREEN command is in. Look at this example: SCREEN 13 PSET (1,1), 43 This command will display one yellow pixel at the coordinates 1, 1. The coordinates are X and Y coordinates, like any other mathematical situation. So the PSET command has to have this layout to function properly: PSET ([X coordinate], [Y coordinate]), [Colour of Pixel] Remember that X coordinates are those that go left to right on the screen and Y coordinates are those that go Up to Down on the screen. LINE LINE [[STEP](x1!,y1!)]-[STEP](x2!,y2!) [,[color%] [,[B | BF] [,style%]]]    STEP          Specifies that coordinates are relative to the current                    graphics cursor position.   (x1!,y1!),    The screen coordinates of the start of the line and of   (x2!,y2!)     the end of the line.    color%        A color attribute that sets the color of the line or                    rectangle. The available color attributes depend on your                    graphics adapter and the screen mode set by the most                    recent SCREEN statement.    B             Draws a rectangle instead of a line.   BF            Draws a filled box.    style%        A 16-bit value whose bits set whether or not pixels are                    drawn. Use to draw dashed or dotted lines. This simple program displays a line:   Screen 13   LINE (160,10)-(100,50),13   CIRCLE CIRCLE (100, 100), 25, 4,0,3.14 This displays a circle at the coordinates. The layout of the function is as follows: CIRCLE ([X Coordinate], [Y Coordinate]), [Radius], [Colour Number],[Start Angle],[Finish Angle] Remember to put a SCREEN command at the front. PAINT To use PAINT, there must be a SCREEN command declared. The command has coordinates that tells QBasic where to start. The color number specifies the color to paint with, and the border colour tells the PAINT command that it should not paint further when it encounters a pixel of that color. In almost all cases, you will need to use the border colour parameter, simply because without it, PAINT will cover the entire screen. PAINT ([X Coordinate],[Y Coordinate]), [Color Number], [Border Color]1,2,3,4,5,5 SOUND command The SOUND command produces sound of a specific frequency for a specific duration from the PC Speaker. Only one sound can be played at a time. If multiple SOUND statements are issued sequentially, every statement after the first will not execute until after the previous one finishes. For example - SOUND 100 , 20 Plays a 100 hertz wave for 20 ticks, about 1.1 seconds. The lowest frequency allowed by QBasic is 37 Hz, which is roughly a D in the 2nd octave. The highest frequency is 32 767 Hz, but this tone cannot be heard, because the normal human hearing range ends at 20 000 Hz. A secondary function of the SOUND command is to use it to control time in a program.  For x% = 1 TO 10     Print x%     Sound 32000,18.2    NEXT This program will print the numbers 1 to 10, with a 1 second delay between each number. Assignment: A. Tick the correct answer. 1. The number of pixels horizontally and vertically determines the ________ of the monitor. a) resolution b) quality c) display 2. The graphics mode is used to display ___________ on the computer screen. a) text b) graphics c) both text and graphics 3. The ________ command is generally used for medium resolution graphics mode. a) SCREEN 0 b) Screen 1 c) SCREEN 2 4. Value 15 is used to define the color code of _________ a) Bright Blue b) Bright White c) Black 5. The _________ command is used to draw a filled rectangle with X1, Y1, and X2, Y2 as diagonally opposite corners of the rectangle. a) DF b) CF c) BF C. Write the syntax of the following commands. 1. RECTANGLE 2. CIRCLE 3. SOUND 4. PAINT D. Fill in the blanks. 1. The _______ and ______ mode are the two types of modes in QBASIC. 2. The graphics screen is made of very small _______. 3. The bottom – right corner of screen is addressed as_______. 4. The SCREEN mode 0 stands for ______ mode. 5. SCREEN _______ gives graphics mode with 640 x 350 pixels. E. Write the commands to do the following. 1. Draw a line starting from bottom left corner of the screen to the center of the screen. 2. Draw a light cyan colour-filled box in the center of the screen. 3. Draw a circle with center at coordinates 200, 160 and radius as 20. G. Match the following. 1. Default screen mode a. LINE X(20,15)-Y(90,90), 10, BF 2. White b. COLOR 7 3. Vertical line c. BEEP 4. Rectangle d. SCREEN 0 5. Sound e. LINE X(10,80)- Y(100, 80), 3 R/4 (Posted on 12/08/2021) Chapter 4 Conditional statement and looping in QBasic TOPICS TO BE COVERED: 1. CLS Command 2. Input Command  3. Print Command 4. If Statement 5. Loop Structure Main teaching: Quick Beginners, All-Purpose Symbolic Instruction Code is a high-level programming language developed by Microsoft Corporation, the USA in 1985. It is modular programming, where programming is divided into different modules or procedures. QBASIC Statements and Its Purpose CLS is used to Clear the display screen. Rem is used to writing remarks or explanation of the program. Syntax: Rem Remark Input is used to supply or input data from the keyboard. Syntax: Input"prompt message";variable list where prompt message tells the user what type of data is to be entered. Let is used to assign the value of an expression to a variable. It is an optional statement. Syntax: Let Variable=Expression eg. Let A = S Let Name$ = 'Binod' Print is used to display output on the screen in the desired alignment with some spacing in limited ways. It displays data, the value of variable or expression on the screen. Syntax: Print (Expression) Separator (Expression) eg. Print "My Name"; ABC Print "My Phone No"; XXXXXXXX Print (3^2+5)/2 End is used to terminate the Q Basic Program. A statement is an instruction within a program. The four types of statements are; Declaration Statement Assignment Statement Control Statement Input/Output Statement The command is the instructions to the computer to do something to a program as printing, saving etc. Character Set is a set of characters which are valid in Q Basic. It consists of alphabet (A-Z, a-z) number ( 0-9) and special characters like: !,@,#,$,%,%,^,&,*,(,),?,>,<,+,=,',",. Keywords are special words which have special purpose and meaning in Q Basic. Some of the keywords are CLS, REM, PRINT. AND, OR, LEN, WHILE etc. Selection Structure It is also known as a branching structure that allows you to transfer the program control from one part to another on the basis of a specified condition or without condition. Types of Selection Structure: If Statement Select Case Statement If Statement This is a decision-making statement that decides which statement has to be executed on the basis of the specified condition. CLS INPUT A INPUT B LET S = A + B PRINT " SUM OF NUMBER"; S END 1. If…..Then Statement It is a one-way decision-making statement that evaluates a condition and executes the statement if the result of the condition is true. Syntax, If < Condition > Then Statement 1 End If If…..Then…Else Statement It is the two-way decision-making statement that can decide which part of the computer it has executed when the condition is true or false. It executes one part of a program if the condition is true and another part if the condition is not true or false. Syntax: If < Condition > Then Statement 1 Else Statement 2 End if Write a program to check whether the number is divisible by 4 and 5 CLS INPUT" ENTER THE NUMBER" ; N IF N MOD 4 = 0 AND N MOD 6 = 0 THEN PRINT" NUMBER IS DIVISIBLE IS DIVISIBLE BY 4 AND 6" ELSE PRINT" NUMBER IS NOT DIVISIBLE BY 4 AND 6" END IF END Mod=(divisible sign) If…..Then…Else If……Else It is a multi-way decision-making statement that is used when there are two or more conditions to be evaluated. Syntax If < Condition 1 > Then Statement 1 Else If < Condition 2 > Then Statement 2 ----------------------- -------------------- Else Statement- N End If ( N= Any Number) Loop Structure For……..Next Statement It repeats a block of statement for a specified number of times. 1,2,3,4…..10 CLS FOR K = 1 TO 10 PRINT K ; NEXT K END While…..Wend Statement It executes a  block of statements repeatedly until the specified condition is true. 1,4,7,10…….25 CLS A = 1 WHILE A < = 25 PRINT A A = A +3 WEND END Do…Loop Statement It repeats a part of the program while a condition is true or until the condition becomes true. 100,90,80……up to 10 CLS S = 100 DO PRINT A; A = A -10 LOOP WHILE A > = 10 END Nested Loop The Loop inside the loop structure is called Nested loop. It contains an outer loop and inner loop. 7  7  7  7  7  7  7  7 6  6  6  6  6  6  6 5  5  5  5  5  5 4  4  4  4  4 3  3  3 2  2 1 CLS FOR A = 7 TO 1 STEP -1 FOR B = 1 TO A PRINT A; NEXT B PRINT NEXT A END Watch the video Assignment: A. Tick the correct answer.
1. The statement used to jump to a particular section in the program is
a) MOVE		b) RUN		c) GOTO
2. A loop within another loop is called a
a) Circular loop		b) Nested loop		c) Branched loop
3. The loop used when the user knows exactly how many times the loop has to be repeated is
a) FOR…NEXT		b) DO WHILE…LOOP		c) WHILE…WEND
4. The counter variable increases or decreases by the specified
a) Step value		b) End value		c) Start value
5. This loop is functionally equivalent to DO WHILE…LOOP.
a) FOR…NEXT		b) DO…LOOP WHILE		c) WHILE…WEND
B. Fill in the blanks.
1. In a ___________, if the test condition is initially false, the loop body is not executed at all.
2. In the ___________, the loop body is executed first before checking the condition.
3. The minimum number of times a DO…WHILE executes is ____________.
4. The ___________ section states the steps to be followed if the condition is false.
5. Final value is the number that controls the end of the ________ process.
C. Spot the error in these statements. Write each one correctly.
1. A FOR loop can be terminated with the END FOR statement.
2. DO WHILE…LOOP checks the condition at the bottom of the loop.
3. In a nested statement, the inner statement ends after the outer statement.
4. The default increment value of a counter is equal to 0 in a FOR…NEXT loop.
5. DO…LOOP WHILE is an entry controlled loop.
6. IF…THEN…ELSE is also known as a conditional loop.

  R/3 Posted on (07/07/2021)

Chapter 3 More in Excel

TOPICS TO BE COVERED:

1. Sorting data

2. Filtering data 

3. Conditional formatting

4. Charts

Main teaching:

SORTING DATA

Sorting data in Excel basically means that we can arrange the data according to some specific criteria​.

For a quick sort, click the arrow below the Sort & Filtering icon in the Editing group of the Home ribbon and choose the Sort A to Z / Z to A icons in the Sort & Filter group of the Data ribbon. In Excel 2013, these are labeled Sort Smallest to Largest and vice versa.

For a more complex sort, go to the Home ribbon, click the arrow below the Sort & Filter icon in the Editing group and choose Custom Sort. This takes you to the same Sort dialog box you get with the Sort icon in the Sort & Filter group of the Data ribbon.

1. Under Column, choose the first column that you would like to sort. If you want to sort multiple columns, click the Add Level button.

2. Under Sort On, choose how you would like to sort. Note that Excel can sort by cell or font color in addition to values.

3. Under Order, choose A to Z (ascending), Z to A (descending), or Custom List.

4. Click OK to perform the sort.

FILTERING DATA

Excel Filter is a quick way to display only the information relevant at a given time and remove all other data from view. You can filter rows in Excel worksheets by value, by format and by criteria. After applying a filter, you can copy, edit, chart or print only visible rows without rearranging the entire list. When data is filtered, only rows that meet the filter criteria will display and other rows will be hidden. 

CONDITIONAL FORMATTING

Conditional formatting allows you to automatically apply formatting—such as colors, icons, and data bars—to one or more cells based on the cell value. To do this, you'll need to create a conditional formatting rule. For example, a conditional formatting rule might be: If the value is less than $2000, color the cell red. By applying this rule, you'd be able to quickly see which cells contain values less than $2000.

In our example, we have a worksheet containing sales data, and we'd like to see which salespeople are meeting their monthly sales goals. The sales goal is $4000 per month, so we'll create a conditional formatting rule for any cells containing a value higher than 4000.

1. Select the desired cells for the conditional formatting rule.
   
2. From the Home tab, click the Conditional Formatting command. A drop-down menu will appear. However the mouse over the desired conditional formatting type, then select the desired rule from the menu that appears. In our example, we want to highlight cells that are greater than $4000.
3. 
4. A dialog box will appear. Enter the desired value(s) into the blank field. In our example, we'll enter 4000 as our value. Select a formatting style from the drop-down menu. In our example, we'll choose Green Fill with Dark Green Text, then click OK.
5. 
6. The conditional formatting will be applied to the selected cells. In our example, it's easy to see which salespeople reached the $4000 sales goal for each month.
   

CHARTS

A chart is a powerful tool that allows you to visually display data in a variety of different chart formats such as Bar, Column, Pie, Line, Area, Doughnut, Scatter, Surface, or Radar charts. With Excel, it is easy to create a chart.

Here are some of the types of charts that you can create in Excel.

The Column Chart

The Column Chart effectively compares a single set of data points, but it shines when comparing multiple series. Outlined in red, the image below shows the three data series we're charting. Notice that we do not include the totals in our data series.

Multiple Data Series

Because Excel uses a different color for each data series, it's easy to see how a single series changes over time, or compare multiple series over a given time period. The Clustered Column Chart is especially popular.

The Bar Chart

The Bar Chart is like a Column Chart lying on its side. The horizontal axis of a Bar Chart contains the numeric values. The first chart below is the Bar Chart for our single series, Flowers.

When to use a Bar Chart versus a Column Chart depends on the type of data and user preference. Sometimes it is worth the time to create both charts and compare the results. However, Bar Charts do tend to display and compare a large number of series better than the other chart types.

The Pie Chart

A Pie Chart displays one series of data. A data series is a row or column of numbers used for charting. In the worksheet below, we have outlined a single data series. If we had selected multiple series for the Pie Chart, Excel would ignore all but the first.

Single Data Series

Excel uses the row heading (series identifier) for the chart title and displays the data as proportional slices of a pie (1st image below). One can customize the design of the pie chart so either numeric values or their percentages display on top of the slices of pie.

The legend can be moved to the top, bottom, left, right, or top right ("corner" in older versions) of the chart. Legend names can be changed by changing the column headings in the sheet or editing the chart directly in new Excel versions. 

Now watch the video

Video 01

Video 02

Assignment:

1. To print your worksheet, which option under the File tab would you choose?
a) Print	b) Preview	c) Recent
2. Which of these is a type of charts available in Excel?
a) Perimeter	b) Volume	c) Area
3. Which option under the Sort & Filter group of the Data tab removes all filters from the list?
a) Remove	b) Filter	c) Delete Filter
4. As soon as you insert a chart, how many new tabs appear on the Office ribbon?
a) Two	b) Three	c) Four
5. Which of these arranges the data in a list in a particular order?
a) Sorting	b) Formatting	c) Filtering
6. Which of these chart types is used when a comparison among individual items is to be shown?
a) Column	b) Line	c) Bar
B. Fill in the blanks.
1. To prepare a filtered list at a new place, choose the ________ option in the Advanced Filter dialog box.
2. Excel can sort data in other fields using the __________ option of the Sort dialog box.
3. ________ make the comparison of data easy at different points.
4. Excel first sorts __________, then __________, followed by blank cells.
5. The Auto Filter option lists down the filtering options ____________.
6. When scientific data or share market statistics is to be plotted, _________ chart type is used.
7. Click _________ to set the number of printouts of the worksheet you need.
C. Which feature of Excel should be used to do the following?
1. To present data in a pictorial form
2. To compare large sets of data
3. To find the bottom 10 items of a list
4. To get particular information from a list without changing the order of the list
5. To arrange the data of a column in descending order
D. Match the following.
1) Filter		a) arrange
2) Auto Filter		b) separate
3) Sort		c) one criterion
4) Advanced		d) more criteria
F. Which tab should be clicked to do the following?
1. To print a worksheet
2. To change a chart type
3. To get the Advanced Filter option
4. To create a chart for given data
5. To sort a given column
6. To perform conditional formatting on data
G. Under which tab are the following options found?
1. Conditional formatting
2. Charts
3. Chart title
4. Chart styles

 R/2 (Posted on 7/6/2021)

Chapter 2 Formulas and functions in MS Excel 2010 

The basics of Excel formulas

• A Formula is an expression that calculates values in a cell or in a range of cells.
  For example =A2+A2+A3+A4 is a formula that adds up the values in cells A2 through A4.
• Function is a predefined formula already available in Excel. Functions perform specific calculations in a particular order based on the specified values, called arguments, or parameters.

For example, instead of specifying each value to be summed like in the above formula, you can use the SUM function to add a range of cells. For example =SUM(A2:A4)

You can find all available Excel functions in the Function Library on the Formulas tab:

There exist 400+ functions in Excel, and the number is growing with every new version. Of course, it's next to impossible to memorize all of them, and you actually don't need to. The Function Wizard will help you find the function best suited for a particular task, while the Excel Formula Intelligence will prompt the function's syntax and arguments as soon as you type the function's name preceded by an equal sign in a cell:

Clicking the function's name will turn it into a blue hyperlink, which will open the Help topic for that function.

SUM
The first Excel function you should be familiar with is the one that performs the basic arithmetic operation of addition:

SUM(number1, [number2], …)

In the syntax of all Excel functions, an argument enclosed in [square brackets] is optional, other arguments are required. Meaning, your Sum formula should include at least 1 number, reference to a cell or a range of cells. For example:

=SUM(B2:B6) adds up values in cells B2 through B6.

=SUM(B2, B6) adds up values in cells B2 and B6.

If necessary, you can perform other calculations within a single formula, for example, add up values in cells B2 through B6, and then divide the sum by 5:

=SUM(B2:B6)/5

To sum with conditions, use the SUMIF function: in the 1st argument, you enter the range of cells to be tested against the criteria (A2:A6), in the 2nd argument - the criteria itself (D2), and in the last argument - the cells to sum (B2:B6):

=SUMIF(A2:A6, D2, B2:B6)

In your Excel worksheets, the formulas may look something similar to this:


AVERAGE

In Excel the AVERAGE function does exactly what its name suggests, i.e. finds an average, or arithmetic mean, of numbers. Its syntax is similar to SUM's:

AVERAGE(number1, [number2], …)

Having a closer look at the formula from the previous section (=SUM(B2:B6)/5), what does it actually do? Sums values in cells B2 through B6, and then divides the result by 5. And what do you call adding up a group of numbers and then dividing the sum by the count of those numbers? Yep, an average!

So the Excel AVERAGE function performs these calculations behind the scenes. So, instead of dividing sum by count, you can simply put this formula in a cell:

=AVERAGE(B2:B6)

To average cells based on condition, use the following AVERAGEIF formula, where A2:A6 is the criteria range, D3 is the criteria, and B2:B6 are the cells to average:

=AVERAGEIF(A2:A6, D3, B2:B6)

MAX & MIN

The MAX and MIN formulas in Excel get the largest and smallest value in a set of numbers, respectively. For our sample data set, the formulas entered will be as folows:

=MAX(B2:B6)

=MIN(B2:B6)

COUNT & COUNTA

If you are curious to know how many cells in a given range contain numeric values (numbers or dates), don't waste your time counting them by hand. The Excel COUNT function will bring you the count in a heartbeat:

COUNT(value1, [value2], …)

While the COUNT function deals only with those cells that contain numbers, the COUNTA function counts all cells that are not blank, whether they contain numbers, dates, times, text, logical values of TRUE and FALSE, errors or empty text strings (""):

COUNTA (value1, [value2], …)

For example, to find out how many cells in column B contain numbers, use this formula:

=COUNT(B1:B10)

To count all non-empty cells in column B, we will have to enter:

=COUNTA(B1:B10)

In both formulas, you use the so-called "whole column reference" (B:B) that refers to all the cells within column B.

Video 1

Assignments:

A. Choose the correct option from the options given below.
1. Which  of the following is used to select a range of data automatically?
a) property	b) cell address	c) function
2. Which function is used to find how many cells contain numbers and not text?
a) TEXT	b) NUMBER	c) COUNT
3. Which function is used to find the highest number in a set of numbers or series of cells?
a) MAX	b) MIN	c) HIGH
4. Which pre-defined feature is known as functions in Excel?
a) property	b) formula	c) data
5. Excel saves the formula using cell address and not this.
a) cell column	b) cell contents	c) cell rows

C. To which function category do the following belong.

1. AVERAGE

2. SUM

3. COUNT

4. MAX

5. POWER

E. Fill in the blanks.

1. A formula in Excel has to be started with ___________ sign.

2. The functions are found under _________ tab.

3. The cell address AB143 denotes _________ row number and _________ column label.

4. A cell address is nothing but ________ of the row and column where the cell is located.

5. The absolute cell address for a cell located in column Z and row 10 is ___________.

6. Quotient is a type  of _____________ function.

F. Match the following.

1. Functions		a) two function arguments
2. AutoSum		b) formulas
3. Quotient		c) shortcut in the Formula tab
4. Mixed cell address		d) spreadsheet
5. Relative cell address		e) HR$02
6. Excel		f) $K$23
7. Absolute cell address		g) CD13

G. Give two examples for the following.

1. Cell address

2. Mathematical functions

3. Absolute cell address

4. Statistical functions

5. Relative cell address

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Assignment: Copy these important points in your Computer Copy and learn them for your Self Assessment Test.
Points to Remember

1. The two main components of a computer are hardware and software.
2. Hardware consists of all the physical parts that make up a computer system.
3. Software is the name given to the instructions and programs that make the hardware work.
4. The different stages of the advancement in software technology which is directly linked to development in computer programming languages is called generation of computer languages.
5. A computer understands only binary language which is in the form of 0s (zeros) and 1s(ones) only as it is a machine that understands only two situations, OFF and ON in which 0 is OFF and 1 is ON.
6. Machine language is also known as first generation language.
7. Machine language is the only language which the computer understands.
8. Assembly language is known as second generation language.
9. Machine language and assembly languages are Low Level Language.
10. High Level Language is the third generation language.
11. High Level Languages use commands and code which is in common English.
12. The first high level language was designed in the 1950s.
13. Some examples of High Level Languages are C, C++, C#, JAVA, FORTRAN, BASIC and COBOL.
14. Fourth generation languages are used mainly in database programming. For example – PL/SQL, FoxPro, Stata, Oracle and Visual Basic.
15. A fifth-generation programming language (5GL) is a programming language based on problem-solving using constraints given to the program, rather than using an algorithm written by a programmer. This is also known as artificial intelligence language.
16. Based on their use, software is classified into two types Application software and System software. 
17. System software refers to software that is developed to operate and control the computer hardware.
18. An operating system is the software that controls and organizes the working of a computer. Windows 7, Windows 10, Linux, Android, Mac are all operating systems. It acts as an interface between the user and the hardware.
19. A device driver is software which enables hardware devices to communicate with the computer's operating system.
20. Utility programs are software designed to perform a specific task related to the operation of a computer. Disk Defragmenter and System Restore are utility programs.
21. An assembler is a language processor that translates the programs written in assembly language into machine language.
22. An Interpreter is a language processor that translates high level language into the machine language line by line.
23. A compiler is a language processor that translates the entire high level language program into machine language at once.
24. Application software is used to perform specialized tasks given by the user and is also referred to as end user programs.
25. Word processors are used to create, edit and format text documents. Microsoft Word, WordPerfect, Writer and Kword are all Word Processors.
26. Desktop Publishing software (DTP) is used to create newspapers, magazines, brochures, still advertisements etc.
27. Database Management System (DBMS) software is used to create, store, modify and sort data stored in a database such as Microsoft Access, Oracle, Microsoft SQL Server.
28. A database is an organised collection of related data.
29. Spreadsheets are used to calculate, compare and analyze data which is used to prepare different reports based on that data. Microsoft Excel, Lotus 1-2-3 are Spreadsheets.
30. Presentation software is used to create presentations which include sound, music, videos, charts and animation like Microsoft PowerPoint, Corel Presentation and Impress.
31. Customized software is also known as bespoke software. Some examples are the software used for railways, banks and hospitals which are tailored to their specific need.
32. Number systems are the techniques used to represent numbers in the computer system architecture in which every value that you save or get from computer memory has a defined number system.
33. Computer architecture supports four types of number systems, (i) Binary number system, (ii) Octal number system, (iii) Decimal number system and (iv) Hexadecimal (hex) number system
34. The base of binary number system is 2, because it has only two digits.
35. Octal number system has only eight (8) digits from 0 to 7. Every number value is represented by 0,1,2,3,4,5,6 and 7 in this number system.
36. The base of octal number system is 8, because it has only 8 digits.
37. Decimal number system has only ten (10) digits from 0 to 9. Every number value is represented by 0,1,2,3,4,5,6, 7, 8 and 9 in this number system.
38. The base of decimal number system is 10, because it has only 10 digits.
39. A Hexadecimal number system has sixteen (16) alphanumeric values from 0 to 9 and A to F. Every number value is represented by 0,1,2,3,4,5,6, 7, 8, 9, A, B, C, D, E and F in this number system.
40. The base of hexadecimal number system is 16, because it has 16 alphanumeric values.

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 R/1 (Posted on 7/05/2021) 

Chapter 1 Computer Software and Languages

TOPICS TO BE COVERED:

1. Introduction to computer language

2. Generation of computer languages 

    * Low level languages

    * High level languages
    * 4GLs
    * 5th generation languages
3. Computer software and its types

    * Operating software

    * Application software

4. Number system

Main teaching:

Computer language

A computer language is a system of communication with a computer. Such languages are used to create computer code or program code, which are the set of instructions forming a computer program which is executed by a computer. It is one of two components of the software which runs on computer hardware, the other being the data.

There are mainly three different languages with the help of which we can develop computer programs. And they are –

• * Machine Level language
• * Assembly Level Language and
• * High Level Language

Machine Level Language

Computers can understand only the language of Digital Electronics. Digital Electronics deals with presence and absence of voltages. Within the computer there are two logics which can play their role. These logics are –

• Positive Logic – Here presence of voltage will be denoted by 1 and absence of voltage will be denoted by 0
• Negative Logic – Here presence of voltage will be denoted by 0 and absence of voltage will be denoted by 1

A computer can follow only one of the logics at a time, not both the logics simultaneously. To make the computer understand, a program can be written using only zeros (0s) and ones (1s). Even data can be specified and represented using only 0s and 1s. Such a program is called Machine Language program. Machine language was the first in the evolution of computer programming languages. Computers directly understands a program written in machine language. Hence, machine language programs does not require any translator to convert from one form to another. In fact, even to this day, computers can only understand Machine language which is in binary that is 0 and 1.

Assembly Level Language

After machine level language, the next level of development in the evolution of computer languages was the Assembly Language. Machine level language uses only binary language. But on the other hand, assembly language uses mnemonics or symbolic instructions in place of a sequence of 0s and 1s. For example, to add register A and B in a computer, assembly language uses the mnemonic ‘ADD B’ in place of 10001111. In assembly language, we use symbolic names to denote addresses and data. A number of such examples are dealt with in the successive chapters. Thus writing a program in assembly language has advantages over writing the same in a machine language.

High Level Language

High level language is the next development in the evolution of computer languages. Examples of some high-level languages are given below –

• * PROLOG (for “Programming Logic”);
• * FORTRAN (for ‘Formula Translation’);
• * LISP (for “List Processing”);
• * Pascal (named after the French scientist Blaise Pascal).

High-level languages are English-like language, with less words known as keywords and fewer ambiguities. Each high level language will have its own syntax and keywords. The meaning of the word syntax is grammar.

Fourth Generation Languages :
These are languages that consist of statements that are similar to statements in the human language. These are used mainly in database programming and scripting. Example of these languages include Perl, Python, Ruby, SQL, MatLab(Matrix Laboratory).
Fifth Generation Languages :
These are the programming languages that have visual tools to develop a program. Examples of fifth generation language include Mercury, OPS5, and Prolog.

Both Machine Language and Assembly Language are low level languages. High Level Languages and the Fourth & Fifth Generation Languages are all high level languages.

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Computer software

Software is a set of programs, which is designed to perform a well-defined function. A program is a sequence of instructions written to solve a particular problem.

There are two types of software −

• * System Software
• * Application Software

System Software

A system software is a collection of programs designed to operate, control, and extend the processing capabilities of the computer itself. System software is generally prepared by the computer manufacturers. These software products comprise of programs written in low-level languages, which interact with the hardware at a very basic level. System software serves as the interface between the hardware and the end users.

Some examples of system software are Operating System, Compilers, Interpreter, Assemblers, etc.

Here is a list of some of the most prominent features of a system software −

• * Fast in speed
• * Difficult to design
• * Difficult to understand
• * Less interactive
• * Smaller in size
• * Difficult to manipulate
• * Generally written in low-level language

Application Software

Application software products are designed to satisfy a particular need of a particular environment. All software applications prepared in the computer lab can come under the category of Application software.

Application software may consist of a single program, such as Microsoft's notepad for writing and editing a simple text. It may also consist of a collection of programs, often called software package, which work together to accomplish a task, such as a spreadsheet package.

Examples of Application software are as follows −

• * Income Tax Software
• * Railways Reservation Software
• * Microsoft Office Suite Software
• * Microsoft Word
• * Microsoft Excel
• * Microsoft PowerPoint

Features of application software are as follows −

• * Close to the user
• * Easy to design
• * More interactive
• * Speed is slow. 
• * Generally written in high-level language
• * Easy to understand
• * Easy to manipulate and use
• * Bigger in size and requires large storage space

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Number system
A computer can understand the positional number system where there are only a few symbols called digits and these symbols represent different values depending on the position they occupy in the number.

The value of each digit in a number can be determined using −

• * The digit
• * The position of the digit in the number
• * The base of the number system (where the base is defined as the total number of digits available in the number system)

Decimal Number System

The number system that we use in our day-to-day life is the decimal number system. Decimal number system has base 10 as it uses 10 digits from 0 to 9. In the decimal number system, the successive positions to the left of the decimal point represent units, tens, hundreds, thousands, and so on.

Each position represents a specific power of the base (10). For example, the decimal number 1234 consists of the digit 4 in the units position, 3 in the tens position, 2 in the hundreds position, and 1 in the thousands position. Its value can be written as

1234 = (1 x 1000)+ (2 x 100)+ (3 x 10)+ (4 x l)
         

          = (1 x 103)+ (2 x 102)+ (3 x 101)+ (4 x l00)
          = 1000 + 200 + 30 + 4

S.No.	Number System and Description
1	Binary Number System Base 2. Digits used : 0, 1
2	Octal Number System Base 8. Digits used : 0 to 7
3	Hexa Decimal Number System Base 16. Digits used: 0 to 9, Letters used : A- F

Binary Number System

Characteristics of the binary number system are as follows −

• Uses only two digits, 0 and 1
• Also called the base 2 number system
• Each position in a binary number represents a 0 power of the base (2). Example 20
• Last position in a binary number represents a x power of the base (2). Example 2x where x represents the last position - 1.

Example

Binary Number: (10101)2

Calculating Decimal Equivalent −

Step	Binary Number	Decimal Number
Step 1	(10101)2	((1 x 24) + (0 x 23) + (1 x 22) + (0 x 21) + (1 x 20))10
Step 2	(10101)2	(16 + 0 + 4 + 0 + 1)10
Step 3	(10101)2	2110

Note − 101012 is normally written as 10101.

Watch video no. 3

Assignment: Do all exercises in your computer Science Copy, Sl. No. 43.
Read chapter 1 and do the following exercises.

A. Choose the correct option from the one given.

1. Microsoft Word is a type of _______.
a) application software	b)  system software	c) plug-in software
2. A computer understands only__________.
a) binary numbers	b) decimal numbers	c) letters
3. Which language is closer to human languages?
a) High level languages	b) Low level languages	c) 4GL
4. Which of the following is a spreadsheet program?
a) Lotus 1-2-3	b) Impress	c) Oracle
5. The binary system uses only _______.
a) 3 single digits	b) 10 single digits	c) 2 single digits
B. Fill in the blanks.
1. ________ is an example of systems running with artificial intelligence.
2. _______ is used to help in designing of a product.
3. _______ software is the same for all the users who are operating on  that software
4. _______ programs are necessary for the smooth operation of the  computer system.
5. System software is developed to ________ and ________ the  computer.
6. The DBMS is used to _______ the database and find _______ easily.

C. Match the following.

1) System Restore		a) General purpose software
2) CAD		b) System software
3) Adobe Photoshop		c) Operating system
4) Railway booking		d) DTP software
5) Mac		e) Customized software

D. Guess who I am.

1)  I am a first generation language.

2)  I am a number system that uses only two digits.

3)  I am a type of application software used to create presentations.

4)  I translate the assembly language into machine language.

5)  I enable the user to use common names in place of 0’s and 1’s.

E. Expand the following abbreviations.
1. LLL	2. FORTRAN	3. COBOL
4. CAD	5. BASIC	6. DBMS
F. Write two examples for each of the following.
1. Language processors	2. HLL	3. Utility programs
4. Operating system	5. DTP software	6. Spreadsheet software

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