what is logo language



WHAT IS LOGO






        Logo :       
  •     The Logo language was developed in the late 1970s and early 1980s by a team led by Seymour Papert.
  •  Their aim was to produce a graphical programming environment which was both powerful and simple to use. 
  • The full form of LOGO is Logic Oriented Graphic Oriented. 
  Program:  A program is a set of instructions or commands that help the computer to perform a specified task. The process of writing a computer program is called programming.

Start MSW LOGO:
  1. Click Start button. 
  2.  Select All Programs.
  3.  Select Microsoft Windows Logo program. 
  4. Click Microsoft Windows Logo. 


         Parts of MSW Logo screen :

There are five menu in the menu bar. 
  • File 
  • Bitmap
  • Set
  • Zoom
  • Help
File : File gives you a list of things you can do with your procedures; things like Load them into your workspace, Save them, Save As them using another name, Edit them and Erase them

Bitmap :Bitmap is a technical term for picture. This menu includes commands for working with that you design.

Set :Set can change the type of letters and numbers that Logo uses by setting the "font" menu. You can also set colors.

Zoom: You can zoom in on your pictures to make them bigger. Or you can Zoom out to make them smaller

MSW Logo window is divided into two main parts :
  1. The Main screen or Graphic screen
  2. The Commander window
THE MAIN SCREEN OR GRAPHIC SCREEN
The upper portion of LOGO with white blank area with a triangle in screen of Logo. It show the result of the command. 

It is also called Graphic Screen.

The main screen displays the results of work done in Logo.

Instructions given in Logo language are known as commands. 

The figure create the logo commands are displayed in this area.
The Commander window

This is the place from where you give the commands and control the processing. It is divided into three parts:
  1. Command Input box 
  2.  Recall List box 
  3.  Control/Command buttons
Command Input box

 It is the area where you type Logo commands and execute  pressing the ENTER key or by clicking the Execute button.

Recall List box 

It records and maintains all commands that you type in the input box.
 If the list of commands goes out of view, you can click the scroll bar commands
 
Control/Command buttons

There are eight control buttons, which are meant for part actions. These are :
  1. Halt
  2. Trace
  3. Pause
  4. Status
  5. Step 
  6. reset
  7. Execute
  8. Edall 
Halt : It immediately stops the Logo processing.

Trace : It turns on tracing for debugging your programs and removes errors. Click the button again disables tracing.

Pause : It stops the execution of commands temporarily

Status : It displays a status window showing current settings in Logo. 

Step: It on step-wise method for debugging your program. Every line will be run only after you check it and click OK.

Reset: It clears the Logo main screen/output screen.

Execute: It executes or runs the commands given in the Input Box

Edall :It is used for advance purposes.


LOGO TERMINOLOGIES

Trutle:
A Small triangle symbol at the centre of the main screen is called a turtle. 
The top pointed end of the turtle is called its head
The wide base at the bottom is called its tail. 
Turtle moves on the screen according to the commands or instructions given through the Input box.

Turtle Home
When you start Logo, the turtle is present at the centre of the screen. This is called the Home of the turtle.
 This turtle moves on the screen by following the commands. 

Program
It is a set of orders or commands given to the LOGO turtle. 
Turtle understands these commands and executes them accordingly.

Primitive

In Logo, the turtle moves or acts according to your commands. 
The commands given to the turtle are known as primitives. 
Commands are typed in the command input box.
 These commands are executed by clicking the Execute button or by pressing the enter key.

Moving the Turtle

The turtle can move anywhere in the main screen area.
 A turtle draws a line when it moves in any direction.
 This line is called trail. The turtle can move forward and backward.

Exit from Logo

After finishing the work in Logo, you must exit Logo.
There are  two method to exit from logo :
Type Bye command  in the Input box and press Enter key or  Execute button.
            Or 
Click on File menu
Click on Exit option

Logo Primitive



DRAWING COMMANDS  

The simple Logo drawing commands move the turtle forward and backward and turn it right or left.

FD: Forward

BK: Backward

LT: Left

RT: Right

CS: Clear Screen

Forward Command (FD)

Forward Command is used to move the Turtle in forward direction. 
The short form for forward command is FD. 
When the turtle moves, it leaves a trail (Footstep) behind it. 
To use this command, type in Input box: <FD><SPACE><NUMBER OF STEPS> <ENTER KEY> 

Backward Command (BK)

Backward Command is used to move the Turtle in Backward direction. 
The short form for Backward command is BK. 
When the turtle moves, it leaves a trail (Footstep) behind it. 
To use this command, type in Input box: <BK><SPACE><NUMBER OF STEPS> <ENTER KEY> 

Right Command (RT)

Right Command is used to turn the turtle towards right direction (clockwise). 
These form for right command is RT.
 We will also have to give the angle by which the turtle should turn.
<RT><SPACE><NUMBER OF ANGLE> <ENTER KEY> 

Left Command (LT)

Left Command is used to turn the turtle towards Left direction (anticlockwise). 
These form for Left command is LT.
 We will also have to give the angle by which the turtle should turn.
<LT><SPACE><NUMBER OF ANGLE> <ENTER KEY> 

Home Command

Home Command brings the turtle back from anywhere on the screen to its starting position.
 This command is not followed by any number.

Pen up Command

This command orders the turtle to lift up the pen from the screen and move without drawing a line on the screen. 
The short form of this command is PU. 

Pen down Command

While using PEN UP command. 
we have seen that turtle stops drawing on the screen. 
Suppose we want to draw again, what will we do? 
We can use PEN DOWN or PD command.
 This command instructs the turtle to put the pen down on the screen and continue drawing 

Clear Screen Command

Clear Screen Command is used to clear or erase the drawing on the screen and bring the turtle to its HOME position. 
The short form of clear screen command is CS.
 To use this command.
type in Input box: 
<CS><ENTER KEY> 




Create a Triangle Logo Language
     
         FD 50
         RT 90
         FD 50
         HOME



Create a Square Logo Language
     
         FD 50
         RT 90
         FD 50
         RT 90
         FD 50
         HOME

Create a Rectangle Logo Language
     
         FD 50
         RT 90
         FD 100
         RT 90
         FD 50
         HOME








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