Computer - Components

All types of computers follow a same basic logical structure and perform the following five basic operations for converting raw input data into information useful to their users.

Sr.No.	Operation	Description
1	Take Input	The process of entering data and instructions into the computer system
2	Store Data	Saving data and instructions so that they are available for processing as and when required.
3	Processing Data	Performing arithmetic, and logical operations on data in order to convert them into useful information.
4	Output Information	The process of producing useful information or results for the user, such as a printed report or visual display.
5	Control the workflow	Directs the manner and sequence in which all of the above operations are performed.

Input Unit

This unit contains devices with the help of which we enter data into computer. This unit makes link between user and computer. The input devices translate the information into the form understandable by computer.

CPU (Central Processing Unit)

CPU is considered as the brain of the computer. CPU performs all types of data processing operations. It stores data, intermediate results and instructions(program). It controls the operation of all parts of computer.

CPU itself has following three components

• ALU(Arithmetic Logic Unit)
• Memory Unit
• Control Unit

Output Unit

Output unit consists of devices with the help of which we get the information from computer. This unit is a link between computer and users. Output devices translate the computer's output into the form understandable by users.

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Computer - Types

Computers can be broadly classified by their speed and computing power.

Sr.No.	Type	Specifications
1	PC (Personal Computer)	It is a single user computer system having moderately powerful microprocessor
2	WorkStation	It is also a single user computer system which is similar to personal computer but have more powerful microprocessor.
3	Mini Computer	It is a multi-user computer system which is capable of supporting hundreds of users simultaneously.
4	Main Frame	It is a multi-user computer system which is capable of supporting hundreds of users simultaneously. Software technology is different from minicomputer.
5	Supercomputer	It is an extremely fast computer which can execute hundreds of millions of instructions per second.

PC (Personal Computer)

A PC can be defined as a small, relatively inexpensive computer designed for an individual user. PCs are based on the microprocessor technology that enables manufacturers to put an entire CPU on one chip. Businesses use personal computers for word processing, accounting, desktop publishing, and for running spreadsheet and database management applications. At home, the most popular use for personal computers is playing games and surfing Internet.

Although personal computers are designed as single-user systems, these systems are normally linked together to form a network. In terms of power, now-a-days High-end models of the Macintosh and PC offer the same computing power and graphics capability as low-end workstations by Sun Microsystems, Hewlett-Packard, and Dell.

Workstation

Workstation is a computer used for engineering applications (CAD/CAM), desktop publishing, software development, and other such types of applications which require a moderate amount of computing power and relatively high quality graphics capabilities.

Workstations generally come with a large, high-resolution graphics screen, large amount of RAM, inbuilt network support, and a graphical user interface. Most workstations also have a mass storage device such as a disk drive, but a special type of workstation, called a diskless workstation, comes without a disk drive.

Common operating systems for workstations are UNIX and Windows NT. Like PC, Workstations are also single-user computers like PC but are typically linked together to form a local-area network, although they can also be used as stand-alone systems.

Minicomputer

It is a midsize multi-processing system capable of supporting up to 250 users simultaneously.

Mainframe

Mainframe is very large in size and is an expensive computer capable of supporting hundreds or even thousands of users simultaneously. Mainframe executes many programs concurrently and supports many simultaneous execution of programs

Supercomputer

Supercomputers are one of the fastest computers currently available. Supercomputers are very expensive and are employed for specialized applications that require immense amount of mathematical calculations (number crunching). For example, weather forecasting, scientific simulations, (animated) graphics, fluid dynamic calculations, nuclear energy research, electronic design, and analysis of geological data (e.g. in petrochemical prospecting).

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Computer - Applications

Following list demonstrates various applications of computers in today's arena.

Business

A computer has high speed of calculation, diligence, accuracy, reliability, or versatility which made it an integrated part in all business organisations.

Computer is used in business organisations for:

• Payroll calculations
• Budgeting
• Sales analysis
• Financial forecasting
• Managing employees database
• Maintenance of stocks etc.

Banking

Today banking is almost totally dependent on computer.

Banks provide following facilities:

• Banks provide online accounting facility, which includes current balances, deposits, overdrafts, interest charges, shares, and trustee records.
• ATM machines are making it even easier for customers to deal with banks.

Insurance

Insurance companies are keeping all records up-to-date with the help of computers. The insurance companies, finance houses and stock broking firms are widely using computers for their concerns.

Insurance companies are maintaining a database of all clients with information showing

• procedure to continue with policies
• starting date of the policies
• next due installment of a policy
• maturity date
• interests due
• survival benefits
• bonus

Education

The computer has provided a lot of facilities in the education system.

• The computer provides a tool in the education system known as CBE (Computer Based Education).
• CBE involves control, delivery, and evaluation of learning.
• The computer education is rapidly increasing the graph of number of computer students.
• There are number of methods in which educational institutions can use computer to educate the students.
• It is used to prepare a database about performance of a student and analysis is carried out on this basis.

Marketing

In marketing, uses of computer are following:

• Advertising - With computers, advertising professionals create art and graphics, write and revise copy, and print and disseminate ads with the goal of selling more products.
• At Home Shopping - Home shopping has been made possible through use of computerised catalogues that provide access to product information and permit direct entry of orders to be filled by the customers.

Health Care

Computers have become important part in hospitals, labs, and dispensaries. The computers are being used in hospitals to keep the record of patients and medicines. It is also used in scanning and diagnosing different diseases. ECG, EEG, Ultrasounds and CT Scans etc., are also done by computerised machines.

Some major fields of health care in which computers are used are:

• Diagnostic System - Computers are used to collect data and identify cause of illness.
• Lab-diagnostic System - All tests can be done and reports are prepared by computer.
• Patient Monitoring System - These are used to check patient's signs for abnormality such as in Cardiac Arrest, ECG etc.
• Pharma Information System - Computer checks Drug-Labels, Expiry dates, harmful drug’s side effects etc.
• Surgery : Nowadays, computers are also used in performing surgery.

Engineering Design

Computers are widely used in Engineering purpose.

One of major areas is CAD (Computer aided design). That provides creation and modification of images. Some fields are:

• Structural Engineering - Requires stress and strain analysis for design of Ships, Buildings, Budgets, Airplanes etc.
• Industrial Engineering - Computers deal with design, implementation and improvement of integrated systems of people, materials and equipments.
• Architectural Engineering - Computers help in planning towns, designing buildings, determining a range of buildings on a site using both 2D and 3D drawings.

Military

Computers are largely used in defence. Modern tanks, missiles, weapons etc. Military also employs computerised control systems. Some military areas where a computer has been used are:

• Missile Control
• Military Communication
• Military Operation and Planning
• Smart Weapons

Communication

Communication means to convey a message, an idea, a picture or speech that is received and understood clearly and correctly by the person for whom it is meant for. Some main areas in this category are:

• E-mail
• Chatting
• Usenet
• FTP
• Telnet
• Video-conferencing

Government

Computers play an important role in government. Some major fields in this category are:

• Budgets
• Sales tax department
• Income tax department
• Male/Female ratio
• Computerization of voters lists
• Computerization of driving licensing system
• Computerization of PAN card
• Weather forecasting

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Accounting - Process

Accounting cycle refers to the specific tasks involved in completing an accounting process. The length of an accounting cycle can be monthly, quarterly, half-yearly, or annually. It may vary from organization to organization but the process remains the same.

Accounting Process

The following table lists down the steps followed in an accounting process -

1	Collecting and Analyzing Accounting Documents	It is a very important step in which you examine the source documents and analyze them. For example, cash, bank, sales, and purchase related documents. This is a continuous process throughout the accounting period.
2	Posting in Journal	On the basis of the above documents, you pass journal entries using double entry system in which debit and credit balance remains equal. This process is repeated throughout the accounting period.
3	Posting in Ledger Accounts	Debit and credit balance of all the above accounts affected through journal entries are posted in ledger accounts. A ledger is simply a collection of all accounts. Usually, this is also a continuous process for the whole accounting period.
4	Preparation of Trial Balance	As the name suggests, trial balance is a summary of all the balances of ledger accounts irrespective of whether they carry debit balance or credit balance. Since we follow double entry system of accounts, the total of all the debit and credit balance as appeared in trial balance remains equal. Usually, you need to prepare trial balance at the end of the said accounting period.
5	Posting of Adjustment Entries	In this step, the adjustment entries are first passed through the journal, followed by posting in ledger accounts, and finally in the trial balance. Since in most of the cases, we used accrual basis of accounting to find out the correct value of revenue, expenses, assets and liabilities accounts, we need to do these adjustment entries. This process is performed at the end of each accounting period.
6	Adjusted Trial Balance	Taking into account the above adjustment entries, we create adjusted trial balance. Adjusted trial balance is a platform to prepare the financial statements of a company.
7	Preparation of Financial Statements	Financial statements are the set of statements like Income and Expenditure Account or Trading and Profit & Loss Account, Cash Flow Statement, Fund Flow Statement, Balance Sheet or Statement of Affairs Account. With the help of trial balance, we put all the information into financial statements. Financial statements clearly show the financial health of a firm by depicting its profits or losses.
8	Post-Closing Entries	All the different accounts of revenue and expenditure of the firm are transferred to the Trading and Profit & Loss account. With the result of these entries, the balance of all the accounts of income and expenditure accounts come to NIL. The net balance of these entries represents the profit or loss of the company, which is finally transferred to the owner’s equity or capital.
9	Post-Closing Trial Balance	Post-closing Trial Balance represents the balances of Asset, Liabilities & Capital account. These balances are transferred to next financial year as an opening balance.

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Cloud Computing Network as a Service (NaaS)

Network-as-a-Service allows us to access to network infrastructure directly and securely. NaaS makes it possible to deploy custom routing protocols.

NaaS uses virtualized network infrastructure to provide network services to the customer. It is the responsibility of NaaS provider to maintain and manage the network resources. Having a provider working for a customer decreases the workload of the customer. Moreover, NaaS offers network as a utility. NaaS is also based on pay-per-use model.

How NaaS is delivered?

To use NaaS model, the customer is required to logon to the web portal, where he can get online API. Here, the customer can customize the route.

In turn, customer has to pay for the capacity used. It is also possible to turn off the capacity at any time.

Mobile NaaS

Mobile NaaS offers more efficient and flexible control over mobile devices. It uses virtualization to simplify the architecture thereby creating more efficient processes.

Following diagram shows the Mobile NaaS service elements:

NaaS Benefits

NaaS offers a number of benefits as discussed below:

Independence

Each customer is independent and can segregate the network.

Bursting

The customer pays for high-capacity network only on requirement.

Resilience

The reliability treatments are available, which can be applied for critical applications.

Analytics

The data protection solutions are available, which can be applied for highly sensitive applications.

Ease of Adding New Service Elements

It is very easy to integrate new service elements to the network.

Support Models

A number of support models are available to reduce operation cost.

Isolation of Customer Traffic

The customer traffic is logically isolated.

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Cloud Computing Identity as a Service (IDaaS)

Employees in a company require to login to system to perform various tasks. These systems may be based on local server or cloud based. Following are the problems that an employee might face:

• Remembering different username and password combinations for accessing multiple servers.
• If an employee leaves the company, it is required to ensure that each account of that user is disabled. This increases workload on IT staff.

To solve above problems, a new technique emerged which is known as Identity-as–a-Service (IDaaS).

IDaaS offers management of identity information as a digital entity. This identity can be used during electronic transactions.

Identity

Identity refers to set of attributes associated with something to make it recognizable. All objects may have same attributes, but their identities cannot be the same. A unique identity is assigned through unique identification attribute.

There are several identity services that are deployed to validate services such as validating web sites, transactions, transaction participants, client, etc. Identity-as-a-Service may include the following:

• Directory services
• Federated services
• Registration
• Authentication services
• Risk and event monitoring
• Single sign-on services
• Identity and profile management

Single Sign-On (SSO)

To solve the problem of using different username and password combinations for different servers, companies now employ Single Sign-On software, which allows the user to login only one time and manage the access to other systems.

SSO has single authentication server, managing multiple accesses to other systems, as shown in the following diagram:

SSO Working

There are several implementations of SSO. Here, we discuss the common ones:

Following steps explain the working of Single Sign-On software:

• User logs into the authentication server using a username and password.
• The authentication server returns the user's ticket.
• User sends the ticket to intranet server.
• Intranet server sends the ticket to the authentication server.
• Authentication server sends the user's security credentials for that server back to the intranet server.

If an employee leaves the company, then disabling the user account at the authentication server prohibits the user's access to all the systems.

Federated Identity Management (FIDM)

FIDM describes the technologies and protocols that enable a user to package security credentials across security domains. It uses Security Markup Language (SAML) to package a user's security credentials as shown in the following diagram:

OpenID

It offers users to login into multiple websites with single account. Google, Yahoo!, Flickr, MySpace, WordPress.com are some of the companies that support OpenID.

Benefits

• Increased site conversation rates
• Access to greater user profile content
• Fewer problems with lost passwords
• Ease of content integration into social networking sites

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Cloud Computing Software as a Service (SaaS)

Software-as–a-Service (SaaS) model allows to provide software application as a service to the end users. It refers to a software that is deployed on a host service and is accessible via Internet. There are several SaaS applications listed below:

• Billing and invoicing system
• Customer Relationship Management (CRM) applications
• Help desk applications
• Human Resource (HR) solutions

Some of the SaaS applications are not customizable such as Microsoft Office Suite. But SaaS provides us Application Programming Interface (API),which allows the developer to develop a customized application.

Characteristics

Here are the characteristics of SaaS service model:

• SaaS makes the software available over the Internet.
• The software applications are maintained by the vendor.
• The license to the software may be subscription based or usage based. And it is billed on recurring basis.
• SaaS applications are cost-effective since they do not require any maintenance at end user side.
• They are available on demand.
• They can be scaled up or down on demand.
• They are automatically upgraded and updated.
• SaaS offers shared data model. Therefore, multiple users can share single instance of infrastructure. It is not required to hard code the functionality for individual users.
• All users run the same version of the software.

Benefits

Using SaaS has proved to be beneficial in terms of scalability, efficiency and performance. Some of the benefits are listed below:

• Modest software tools
• Efficient use of software licenses
• Centralized management and data
• Platform responsibilities managed by provider
• Multitenant solutions

Modest software tools

The SaaS application deployment requires a little or no client side software installation, which results in the following benefits:

• No requirement for complex software packages at client side
• Little or no risk of configuration at client side
• Low distribution cost

Efficient use of software licenses

The customer can have single license for multiple computers running at different locations which reduces the licensing cost. Also, there is no requirement for license servers because the software runs in the provider's infrastructure.

Centralized management and data

The cloud provider stores data centrally. However, the cloud providers may store data in a decentralized manner for the sake of redundancy and reliability.

Platform responsibilities managed by providers

All platform responsibilities such as backups, system maintenance, security, hardware refresh, power management, etc. are performed by the cloud provider. The customer does not need to bother about them.

Multitenant solutions

Multitenant solutions allow multiple users to share single instance of different resources in virtual isolation. Customers can customize their application without affecting the core functionality.

Issues

There are several issues associated with SaaS, some of them are listed below:

• Browser based risks
• Network dependence
• Lack of portability between SaaS clouds

Browser based risks

If the customer visits malicious website and browser becomes infected, the subsequent access to SaaS application might compromise the customer's data.

To avoid such risks, the customer can use multiple browsers and dedicate a specific browser to access SaaS applications or can use virtual desktop while accessing the SaaS applications.

Network dependence

The SaaS application can be delivered only when network is continuously available. Also network should be reliable but the network reliability cannot be guaranteed either by cloud provider or by the customer.

Lack of portability between SaaS clouds

Transferring workloads from one SaaS cloud to another is not so easy because work flow, business logics, user interfaces, support scripts can be provider specific.

Open SaaS and SOA

Open SaaS uses those SaaS applications, which are developed using open source programming language. These SaaS applications can run on any open source operating system and database. Open SaaS has several benefits listed below:

• No License Required
• Low Deployment Cost
• Less Vendor Lock-in
• More portable applications
• More Robust Solution

The following diagram shows the SaaS implementation based on SOA:

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