Ram and Rom

Memory

The memory considered this section divided in two basic types

• Random access memory (RAM)
• Read only memory (ROM)

The RAM can be explained as a device that temporarily store data. RAM can be read from also written into. The key feature of the RAM is that when power of the computer is switch off the data in the ram in the lost (Volatile Memory)

As access to ram is very much faster than to a permanent storage device, it is an inefficient method to read and write to permanent storage as it will simply slow the processing down a great deal.

ROM as implied by term is a type of memory which can only be read from. This type of memory does not lose its data when the power off the computer is turned off. The most common ROM in the computer is the bios (Basic Input Output System) ROM.

The CMOS (Complementary Metal Oxide Semiconductor) chip is also belongs to volatile memory since it requires power from the battery to retain the data once the computer is turned off.

Type of Database Models

Type of Database Models

Database management systems were first introduced during the 1960s and have continued to evolve during subsequent decades. Some combinations of the fallowing three objectives always drove the development and evolution of database technology.

• To provide greater independence between programs and data
• To manage increasingly complex data types and structures
• To provide easier and faster access to data for non-computer professional

Hierarchical and network database model

The hierarchical and network database management systems (generally regarded as first-generation DBMS) were developed to cope with increasingly complex data structures. Both approach to database structure used physical pointers, or disk addresses, to relate records in different files.

Hierarchical Database Model	Network Database Model
Organized as a family tree structure (simple)	Organized as network structure (complex)
One to many relationship (parent Child)	Many to many relationship
Top most record is the root record	Many records at top level
Whole database depends on root record	Database does not depends on a root record
Data access using pointers	Data access using pointers
Access using navigational records at a time procedure	Access using navigational records at a time procedure
Single access path for a data record	Multiple access paths for a data record
Data record can be duplicated	Data records are not duplicated
Need to write complex quires to get information from multiple branches. (no cross links)	Can write simple quires to get information from multiple branches because cross link available

The Hierarchical database model was developed to overcome the limitation of file processing systems and network model has derived as a solution to problem caused by hierarchical model. And both have following problems.

• Difficult access to data based on navigational records at-a-time procedures.
• Very limited data independence
• No widely accepted theoretical foundation for either model

Numbers and Arithmetic Operations

Type of Numbers

There are sets of numbers that are used so often that they have special names and symbols:

Naturals Numbers 

The Natural Numbers or the counting numbers are whole numbers greater than zero.

Example: 1, 2, 3…

Integers

Integers are whole numbers, negative and positive, including “0”

Example:

Positive Integers: 1, 2, 3…

Non negative Integers: 0, 1, 2, 3 …

Negative Integers: -1, -2, -3…

Non positive Integers: 0, -1, -2, -3…

Rational Numbers

Rational Number is numbers that can be written as a fraction where both the top and bottom of the fraction are whole numbers.

Example:

1.5 = 3/2

0.3333… = 1/3

1.36 = 136/100

2 = 8/4

Irrational Numbers

Any number that is not a Rational Number

Example:  π √2

Real Numbers

All rational and irrational numbers. They can also be positive, negative or Zero.

Square Numbers

Square Numbers are integers that can be written as the square of some other integers, i.e. a product of an integer multiplied by it.

Surds

Surds are numbers left in the from the , where √n “n” is a positive integer that is not a square number.

Introduction to Application package

What are the application packages?

 

The computer running with lots of programs simply called as an application or application software. Everything related to computer can be grouped in two major components as hardware and software.

Some applications bundled as packages with respect to the type of work it can perform. For example, Office applications, graphic design applications, web design applications, desktop publishing applications and so on.

Example:

• Office application
• Desktop application
• Graphic design application
• Web design application
• 3D & video editing Application

Running environment of Computer Application

Different applications are running in different computer system environment. For Example: MSOffice on Windows, not on Linux, Open office running on both of windows and Linux.

Folder Structures and files for managing computer data

The first screen you seen as soon as you logged into the computer is called as “Desktop”. Double click on my computer icon on the desktop in windows environment you will see,

• User document
• Hard disk drive
• Storage device

If you click on the partition of the hard drive you can see files and folders existing in it

Windows Explorer

Windows Explorer window provides a better hierarchical view of the files and folders of a machine running with MS Windows

How to open windows explorer

• Press windows key + “E” key
• Click folder button in the standard button bar in the document window.
• Select Start > All programs > Accessories > Windows explorer

What is the internet ?

What is the internet

The internet a networking infrastructure, it is a massive network of networks. It connects millions of computers together globally [1 Billion by 2006], forming a network in which any computer can communicate with any other computer as long as they are both connected to the internet.

Information that travels over the internet dose so via variety of languages known as protocols (HTTP, FTP, SMTP, IRC, etc...) the basic protocol of the internet are TCP/IP

Much application run on internet, the most popular one is World Wide Web. some of the rest are file transfer, email, UseNet news group, instant messaging, etc...

Global infrastructure

The internet is a giant network spread throughout the world by connecting different type/levels of computers (from personal computer to high-end workstation).

Although these computers are at homes, office, school/universities and government departments, it appears as an information retrieval system with communication facilities to all users of the internet. At the same time it is system which is available on demand at all times.

Communication System

Not like telephone system which as very limited number of services (voice, phone, fax, etc…), the internet has unlimited number of services this property is called generality.

Application which run (execute) at computers connected to the internet can provide these services. Examples:

•             File Transfer
•             Email
•             Instant Messaging
•             Discussion Forums (forums on web site, news group etc.)  

   

The parts of Computer system

The parts of Computer system

A Computer can be classified as a device that takes in raw data as input and processes it and provides information as output. The computer also has the ability to store data and information.

The computer system consists of,

Hardware (physical components)

Software

User (people who use the computer)

That are necessary to make the computer function and to processes data in meaningful way and store data.

Hardware components of a computer

Logical design of the components of the computer

The physical components of the computer system are called computer hardware. All hardware components in a computer can be put in to one of these four categories.

• Processor, memory and integrated devices
• Input device
• Output device
• Storage device

The processor

The processor is device that can only follow the instruction given to it by the programmer. Processor is responsible for all the control of computer system like the brain in human. Major difference between the computer and processor and human brain is that it is incapable of

·         Independent and creative thoughts  

·         Generating new ideas

·         Learning

There are many manufactures of processors in the world

• Intel – Pentium, Celeron and Xeon processors.
• Advanced Micro Devices Inc. (AMD) – Duron and Athlon processors
• Centaur Technologies – Cyrix processors for pc
• IBM – PowerPC
• Motorola – Motorola 6800 are processors manufacture for the apple computer

The most modern processors being manufactured are the

• Hyper-threading processors
• 64 – Bit processors   

Traditional Approach vs Database Approach

Traditional Approach vs Database Approach

The traditional approach to information system design focuses on data processing needs of individual department in an organization without considering the organization as a whole. Each computer application typically designed with its own set of data file and application programs to meet the information requirements of particular department or a user group.

Database approach overcomes the limitation of file oriented system by supporting an integrated, centralized data structure which allows to sharing database by different applications.

Traditional File Approach	Database Approach
Use separate data file for each application	All Application shares a pool of related and integrated data.
Data redundancy – independent data files included a lot of duplicated data.	Minimal data redundancy – Separate data files are integrated in to a single, logical structure.
Same data is recorded and stored in several files.	Each occurrence of a data item is recorded only once.
Data inconsistency – several versions of the same data may exist.	Single version of data exist
Same update must be done in all occurrences of same data item in each file.	Single update is required.
Users have very little opportunity to share data outside of their own application.	A database is developed to share the data among the user who access to it
There is no centralized control for overall data in different files.	There is centralized control for overall data in database.
Data dependence – description of files, records and data items are embedded within individual application programs.	Data independence – the database system separates data descriptions from the application programs that use the data in it
Modification to data files requires the programs which access that file to be modified.	Data structure can be modified without changing the programs accessing the data
High program maintenance	Less program maintenance
Lack of data integration – accessing data in several files are difficult	Data are organized in to a single logical structure with logical relationships defined between associated data
Difficult to manipulation data	Easy to manipulation data