Chapter 1:- What is a Computer?

- Hardware.

- Software.

- Types of Computers.

- Numeral Systems.

- Data Sizes and Speeds.

- Data Coding and Information Decoding

- Computer Networks.

* What is a Computer?•A computer is a device that takes input data such

as numbers, text, sound, image, animations, video, and etc., and converts it, presenting the changed input (processed input) as output data.

• The DATA consists of numbers, text, sound, images, animations, and video.

• The process converts numbers, text, sound, images, animations, and video (data) into usable data, which is called INFORMATION.

• The INFORMATION consists of numbers, text, sound, images, animations, and video that has been converted by the process.

• The DATA is inserted using an input device.

• The Central Processing Unit (CPU) converts data to information.

• The INFORMATION is put on an output device.

•A storage device “MEMORY” is an apparatus for storing DATA and INFORMATION.

• A basic computer consists of 4 components:

1. An Input Device.

2. CPU.

3. An Output Devices.

4. Memory.

• One of the most common Input Devices is the Keyboard, used to enter text.

• A computer will process data DIFFERENTLY based on the kind of data being handled, using a set of instructions called a Program or Routine.

• The CPU and Memory are put into a Computer Case.

•A Computer Monitor is the most commonly used Output Device, for the information processed by the CPU.

• The minimum requirements for a functional COMPUTER SYSTEM include; a keyboard, a case containing a CPU and memory, and a monitor.

* How Computer Works?

• DATA comes in through an Input Device, and is sent to the CPU by Memory.

• The CPU processes the DATA, based on the input data and the program which is installed in the computer memory.

• When the CPU has finished processing the DATA, it is presented through the output device as INFORMATION.

• The INFORMATION can be stored in the computer memory or presented through an Output Device.

* Hardware:

• The term "Hardware" refers to the physical elements of a computer; the machinery or the electronics in a computer.

• A basic computer consists of 4 components:

1. Input Device (or Input Unit).

2. CPU (Central Processing Unit).

3. Memory (or Memory unit).

4. Output device (Output Unit).

* Input unit and Output unit (I/O):

• Input unit sends things (DATA) to the computer and output unit presents things (INFORMATION).

• Input Unit like: keyboard, mouse, flash drive, etc.

• Output Unit like: monitor, printer, speaker, etc.

• Input unit and output unit or Input and output device (I/O) provide a way to interact with a computer.

• (I/O) Examples:1. Keyboard.

2. Monitor.

3. Mouse.

4. Printer.

5. Speakers.

* Memory Unit:

• The Memory Unit allows a computer to remember data and information.

• There are two kinds of memory: Short term memory (RAM) and Long term memory (Hard Disk Drive (HDD) or Compact Disk Drive (CDD).

• When a computer is turned off, it forgets everything in the RAM (short term memory), while it saves everything it will need later into a disk drive (long term memory).

Random Access Memory Compact Disk Drive Hard Disk Drive

(RAM) (CDD) (HDD)

• When DATA is needed by the CPU, it's sent from the hard disk drive (HDD) or compact disk drive (CDD) to the RAM.

• RAM tends to be faster to process, whereas HDD/CDD have more DATA and require longer to process.

• A storage medium gives your computer a place to store DATA and INFORMATION that it might need in order to operate. Some things that could be stored in memory might be: text documents, photos, programs, and the operating system (OS).

* CPU:

• The CPU ( Central Processing Unit) performs arithmetical and logical operations of the computer system.

• The CPU, or processor, is the component of a computer that performs processes.

• Examples of other tasks performed by the CPU include:

1. (I/O) directions (reading data from an input device/writing information to an output device).

2. Storing data in memory.

* Motherboard:•The Motherboard is hardware that makes connections between all of the other components in a computer.

* Expansion Cards:•The expansion cards are electronic circuits that add specific ability to a computer system.

* Power Supply:•A power supply (power supply unit) is a device that provides electrical energy to the computer system.

* Assembled Personal Computer Hardware:

1. Monitor.2. Motherboard.3.CPU.4. Memory (RAM).5. Expansion cards.6. Power supply unit.7. CD.8. Hard disk.9. Keyboard.10. Mouse.

* Software:

• Software enables computer hardware to perform specific tasks.

• Software, commonly known as programs or applications, consists of all the electronic instructions that tell the hardware how to perform a specific task.

• Software is capable of performing many different specific tasks, as opposed to hardware which only perform mechanical tasks that they are designed for.

• There are three major types of software:

1. Operating System software, O.S: Helps run computer hardware and computer

system. The most commonly used O.S software are:

Windows. Mac OS X. Linux.

2. Application software: Allows users to accomplish one or more tasks;

browsing the internet or writing a text document, for example: Microsoft Office Word software. Adobe Photoshop software.

3. Programming Software: Software that assists a programmer in writing

more computer software. Programming software makes it easier to come

up with ideas for a program and make them a reality.

Programming an application is done with a special language that the computer understands, called a programming language.

* Types of Computers:1. Supercomputer:

Supercomputers are the fastest and the most expensive computers. These huge computers are used to solve very complex science and engineering problems. They can do up to ten trillion individual calculations every second.

Supercomputers get their processing power by taking advantage of parallel processing; they use lots of CPUs at the same time on one problem.

2. Server Computer: Servers are a step under supercomputers,

because they don't focus on trying to solve one very complex problem, but try to solve many many similar smaller ones.

An example of a server would be the computers that Wikipedia stores its data on. Those computers have to go and find a certain page and send it to the user.

3. Workstation Computer: Workstations are high-end, expensive computers

that are made for more complex procedures and are intended for one user at a time.

Some of the complex procedures consist of science, math and engineering calculations and are useful for computer design and manufacturing.

4. Personal Computer or PC: PC stands for a Personal Computer, it is also

known as a Microcomputer. Its physical characteristics and low cost are appealing and useful for its users.

The capabilities of a PC have changed greatly since the introduction of electronic computers.

PCs is an all-around device that can be used as a productivity tool, a media server, a gaming machine.

5. Microcontroller: Microcontrollers are mini computers that allow

user to store data and execute simple commands and tasks.

These single circuit devices have minimal memory and program length but are normally designed to be very good at performing a niche task. Many such systems are known as embedded systems. The computer in your car, for example is an embedded system.

* Numeral Systems:• A writing method for expressing numbers is called a “Numeral System".

• In the most common numeral system, we write numbers with combinations of 10 symbols {0,1,2,3,4,5,6,7,8,9}. These symbols are called Digits, and numbers that are expressed using 10 digits are called “Decimal" or "base-10" numbers.

• The other most common numeral systems are Binary, Hexadecimal and Octal.

• The binary numeral system, or base-2 number system, represents numeric values using two symbols: 0 and 1.

* Decimal Numeral System:

• We write numbers with combinations of 10 symbols {0,1,2,3,4,5,6,7,8,9} called Digits. Numbers that are expressed with 10 digits are called "base-10" numbers or "Decimal Numeral System".

• For example:

2 (one digit)

45 (two digit)

643 (three digit)

8785 (four digit)

etc.

• In Decimal Numeral Systems, the value of a digit is multiplied according to its placement in a numerical sequence: (base-number ^ 0,1,2,3,...), from right to left.

First digit = (base-number ^ 0): 10^0 = 1

Second digit =(base-number ^ 1): 10^1 = 10

Third digit =(base-number ^ 2): 10^2 = 100

Fourth digit =(base-number ^ 3): 10^3 = 1000

Etc.

• For example:

20 = (2*10)+(0*1) = 20+0 = 20

456 = (4*100)+(5*10)+(6*1) = 400+50+6

84568 = (8*10000)+(4*1000)+(5*100)+(6*10)+(8*1) = 80000+4000+500+60+8

* Binary Numeral System:

• Numbers expressed with 2 symbols (0, 1) are called Binary, or "base-2" numbers.

• For example:

1 (one-digit-read: 1)

10 (two-digit-read: 1, 0)

100 (three-digit-read: 1,0,0)

1101 (four-digit-read: 1, 1, 0, 1)

etc.

• In the Binary Numeral System, digits have a value specified, this value being equal with (base-number ^ 0,1,2,3,...): (right to left)

First digit (base-number^0): 2^0 = 1

Second digit (base-number^1): 2^1 = 2

Third digit (base-number^2): 2^2 = 4

Fourth digit (base-number^3): 2^3 = 8

etc.

* Converting Binary to Decimal:• To convert binary to decimal, each digit is multiplied by the value of its position, and the results are added.

• For example:10 = (1*2^1) + (0*2^0) = 1*2 + 0*1 = 2 + 0 = 2

→ 10 (binary) =2 (decimal)

101 = (1*2^2) + (0*2^1) + (1*2^0) = 1*4 + 0*2 + 1*1 = 4 + 0 +

1 = 5 → 101 (binary) =5 (decimal )

11001 = (1*2^4) + (1*2^3) + (0*2^2) + (0*2^1) + (1*2^0) =

1*16 + 1*8 + 0*4 + 0*2 + 1*1 = 16 + 8 + 0 + 0 + 1 = 25

→ 11001 (binary) =25 (decimal)

111011 = (1*2^5) + (1*2^4) + (1*2^3) + (0*2^2) + (1*2^1) +

(1*2^0) = 1*32 + 1*16 + 1*8 + 0*4 + 1*2 + 1*1 = 32 + 16 +

8 + 0 + 2 + 1 = 59 → 111011 (binary) =59 (decimal)

* Converting Decimal to Binary:

• To convert decimal to binary, divide the decimal number by 2:

o If there IS a remainder the rightmost column will be a 1.

o If there is NO remainder, the rightmost column will be a 0.

• Then repeat the process, moving one column to the left each time until you have divided down to 1.

* Data Sizes & Speeds:

- Names For Different Sizes Of Data:

1. Bit: A bit is a binary unit, simply a 1 or a 0. A true or a false. It is the most basic unit of data in a computer.

Bits are machine readable.

2. Nibble: A nibble is 4 bits, or half of a byte. One hexadecimal digit is one nibble in size.

3. Byte: In computer science a byte is a unit of measurement of information storage, that equals '8 bits', can be used to represent letters and numbers.

For example, the number 01000001 is 8 bits long, and represents the letter A in 8-bit encoding.

4. KB: A kilobyte, or KB, is a unit of data that equals 1024 bytes, or 2^10.

5. MB: A megabyte, or MB, is a unit of data that equals 1,048,576 bytes, or 2^20.

6. GB: A gigabyte, or GB, is a unit of data that equals 1,073,741,824 bytes, or 2^30.

7. TB: A terabyte, or TB, is a unit of data that equals 1,099,511,627,776 bytes, or 2^40.

- Measurements of Data Speed:

• Data transfer speeds can be measured in bits per second, or in bytes per second.

• A byte is (generally) 8 bits long. Network engineers describe network speeds in bits per second, while web browsers usually measure a file download rate in bytes per second. A lowercase "b" usually means a bit, while an uppercase "B" represents a byte.

1. bps:

Known as bits per second, bps was the main way of describing data transfer speeds several decades ago.

2. Kbps:

Kilobits per second, or 1000 bits per second.

3. Mbps:

Megabits per second, or 1,000,000 bits per second.

Internet service providers usually measure their Internet connectivity in Mbps.

4. Gbps:

Gigabits per second, or 1,000,000,000 bits per second.

Modern local area networks, Internet infrastructure, and consumer Internet connections in some countries can operate at these speeds.

* Data Coding & Information Decoding:

• Unique Code: Data are Numbers, Text, Sounds, Image, Video, etc.; in order to define them in the real world, we are using Numbers (0,...9), an Alphabet (A,...Z) and symbols (@,[,\,...) or a combination of them, for example:

2012 (Number) University (Alphabet)

3 < 5 (Combination of Number & Symbol)

X = (Y*Z) + W-U (Combination of Alphabet & Symbols)

N123 (Combination of Alphabet & Number)

Computers, however, don't understand the definitions for Numbers (0,...9), the Alphabet (A,...Z) and symbols (@,[,\,...), so in order to process those pieces of information a unique code must be assigned to each of them. The unique code for Numbers (0,...9), the Alphabet (A,...Z) and symbols (@,[,\,...) is a binary numeral.

Examples of Unique Codes:

The unique code for 0 is → 00000000

The unique code for 1 is → 00000001

The unique code for " A " is → 01000001

The unique code for " B " is → 01000010

The unique code for " @ " is → 01000000