Learning Computers-Class V

Chapter 1 - Evolution of Computers

Early calculating devices are as follows

·    Abacus was the first calculating device. It was invented by the Chinese about 5000 years ago.

·   Pascaline was invented by Blaise Pascal in 1642.It could do addition and subtraction but not multiplication and division. It is also known as Pascal’s Adding Machine.

·     Napier bones was designed by John Napier to perform multiplication and division.

·     Leibnitz’s calculator was improved upon Pascal’s Adding machine.

·  Jacquard’s loom was designed to use punched cards to control a sequence of operations. Invented by Joseph Marie Jacquard.

·  Difference Engine was invented by Charles Babbage in 1823. It was the first mechanical computer.

·     Analytical Engine was an improved version of Difference Engine. Its concept was based upon today’s computer.

·  Charles Babbage is known as “Father of Computer”. He evolved the concept of a programmable computer.

·     Computer development has been categorized into different generations.

Generation	Year	Development	Examples
First Generation	1949-1956	Vacuum Tubes	UNIVAC I and ENIAC
Second Generation	1956-1963	Transistors	IBM 1401
Third Generation	1964-1971	Integrated Circuits	IBM 360 and Apple 2c
Fourth Generation	1971-present	LSI and Microprocessor	Intel 4004 and Intel 8080
Fifth Generation	Future	Artificial Intelligence	A Robot

·         The different types of computers are:

a)      Supercomputers (They have a very large storage capacity and high processing speeds.)

b)      Mainframe Computers (They are less powerful and less expensive than super computer)

c)       Minicomputers (They are general purpose computers where a large number of people can work together)

d)      Personal Computers ( A micro or Personal computer is the least expensive of all and used at home or for business purpose)

  

UNIVAC               Universal Automatic Computer

ENIAC                   Electronic Numerical Integrator and Computer

IC                            Integrated Circuit

LSI                          Large Scale Integration

VLSI                       Very Large Scale Integration

Chapter 2 – Computer Memory

The capacity of a computer to store data and information is called its memory.

When you give instructions to the computer, these instructions get converted into a new language known as machine language.

The computer only understands language 0’s and 1’s. The digits 0 and 1 are known as binary digits or bits.

The computer’s memory is measured in a byte. A byte consists of a group of 8 bits.    

1 Byte = 8 bits

1 Nibble = 4 bits

1 Kilobyte = 1024 bytes

1 Megabyte = 1024 Kilobytes

1 Gigabyte   = 1024 Megabytes

1 Terabyte   = 1024 Gigabytes

The computer memory is of two types

(a)    Primary memory  (b) Secondary memory

Primary memory or Internal memory stores data and programs currently in use.

Primary memory is of two types: ROM and RAM.

ROM or Read Only Memory is a permanent non-volatile memory.

RAM or Random Access Memory is a temporary volatile memory.

Secondary memory or External memory stores data and programs permanently for future use.

Secondary memory includes.

Hard disk has a storage capacity of 40GB to 550GB.

CD-ROM has a storage capacity of 700MB.

DVD has a storage capacity of 4.7GB to 17GB.

Pen Drive has the storage capacity ranging from 2GB to 32GB.

Floppy disk has a storage capacity of 1.44MB.

Bit          is a single-digit having the value either 0 or 1.

Byte       is a group of 8 bits.

ROM      Read-Only Memory

RAM      Random Access Memory

CD-R      Compact Disk Recordable

CD-RW                 Compact Disk Rewritable

DVD       Digital Versatile Disk

  

Chapter 3 - More on LOGO Primitives

PENUP or PU command tells the turtle to pick up its pen.

PENDOWN or PD command tells the turtle to put its pen down.

PENEREASE or PE command is used to erase the incorrect lines drawn by the turtle.

PENPAINT or PPT command is used to tell the turtle to start its drawing again.

SHOW command is used to display the text, number, etc. in the commander window.

SHOW LOWERCASE command is used to display the text in small letters.  

SHOW UPPERCASE command is used to display the text in capital letters.

SHOW COUNT command is used to display the total number of letters in a word.

SHOW TIME command is used to display the current date and time in a list. 

REPEAT command is used to reduce your task of writing the same commands again and again.

Example:-

Drawing a SQUARE using REPEAT command

REPEAT (number of sides) [FD (length of each side) RT (Degree of angles/number of sides)]

or REPEAT 4 [FD 50 RT 90]

Drawing a CIRCLE

REPEAT 72 [FD 5 RT 360/72] or REPEAT 72 [FD 5 RT 5]

Drawing a Semi Circle

REPEAT 180 [FD 1 RT 1] or REPEAT 180 [FD 1 LT 1]

Drawing the letter “S”

REPEAT 180 [FD 1 LT 1]

REPEAT 90 [FD 1 LT 1]

REPEAT 90 [FD 1 RT 1]

REPEAT 180 [FD 1 RT 1]

SETSCREENCOLOR sets the color of the drawing area with the specified color.

SETSCREENCOLOR [255 0 0] or SETSCREENCOLOR 4

SETPENCOLOR command is used to change the color of the pen.

SETPENCOLOR 4 will display the lines and text in Red color.

SETFLOODCOLOR command is used to set the fill color.

SETFLOODCOLOR 1 D

FILL command is used to fill in the desired color in a region of the graphics window containing the turtle and the bounded lines.

SETFLOODCOLOR [255 0 0] RT 45 FD 10 FILL

List is a group of words separated from each other by a blank space.

Polygon is a closed figure made up of line segments alone. 

Chapter 4 -  LOGO Procedures

LOGO provides two modes of operations

1.       Immediate Mode

2.       Procedure Mode

The LOGO procedure is a set of commands defined by the user. A procedure may contain other procedures or Logo commands.

The difference between a procedure and a command is that a command is already defined in LOGO but a procedure is a set of commands defined by the user.

The command to enter the procedure mode is “To” followed by the procedure name.

You end the procedure with END command.

Procedure name can be a combination of words, letters and symbols.

No Blank space allowed between characters of procedure name.

To execute a procedure, type procedure name and press Enter.

To Save a procedure; File > Save

To Load a procedure; File > Load

To edit a procedure click Edall button in commander window.

To erase a procedure use ERASE command

Primitive is a built-in LOGO command.

Procedure is a set of commands defined by the user.