Computer Sc IT & Management

Cache Memory

2023-01-16T13:58:00.003+05:30

Cache memory is a high-speed memory, which is small in size but faster than the main memory (RAM). The CPU can access it more quickly than the primary memory. So, it is used to synchronize with high-speed CPU and to improve its performance.

A cache memory works on the principle of locality of reference, a term for the phenomenon in which the same values, or related storage locations, are frequently accessed, depending on the memory access pattern. Caching improves access time and reduces data traffic to data sources that have limited throughput.

cache memory is much smaller than main memory. Consequently, it has less storage space. It is also more expensive than main memory, as it is a more complex chip that yields higher performance.

What it sacrifices in size and price, it makes up for in speed. Cache memory operates between 10 to 100 times faster than RAM, requiring only a few nanoseconds to respond to a CPU request.

Difference Between ASCII and EBCDIC

2022-04-05T14:52:00.004+05:30

Difference Between ASCII and EBCDIC

Definition

ASCII is a character encoding standard for electronic communication. EBCDIC is an eight-bit character encoding used mainly on IBM mainframe and IBM midrange computer operating systems.

Stands for

ASCII stands for American Standard Code for Information Interchange. EBCDIC stands for Extended Binary Coded Decimal Interchange Code.

Number of bits Represent a Character

Further, ASCII uses 7 bits to represent a character. EBCDIC uses 8 bits to represent a character.

Number of Characters

Also, ASCII represents 128 (2⁷) characters while EBCDIC represents 256 (2⁸) characters.

Efficiency

Moreover, the same character in ASCII requires 7 bits, but EBCDIC required 8 bits. Therefore, ASCII is more efficient than EBCDIC.

Character Order

Besides, ASCII arranges the characters in consecutive order. EBCDIC groups 9 characters at a time.

Compatibility

Additionally, ASCII is compatible with modern encodings such as Unicode. It is possible to open ASCII files with Unicode. On the other hand, EBCDIC is not compatible with modern encodings such as Unicode.

Conclusion

ASCII and EBCDIC are two character encoding standards. The main difference between ASCII and EBCDIC is that the ASCII uses seven bits to represent a character while the EBCDIC uses eight bits to represent a character.

ASCII & EBCDIC

2022-04-05T14:51:00.000+05:30

ASCII

ASCII stands for American Standard Code for Information Interchange. It is an encoding standard that represents digits, letters, and symbols using numbers. The digits can be 1, 2, 3, etc. while the letters are a, b, c, A, B, C, etc. The symbols are characters like !, $, and #. Therefore, it is possible to convert any piece of text to the corresponding set of numbers using ASCII. This conversion makes it easier to store them in the computer memory.

ASCII (American Standard Code for Information Interchange) is the most common character encoding format for text data in computers and on the internet. In standard ASCII-encoded data, there are unique values for 128 alphabetic, numeric or special additional characters and control codes.

ASCII encoding is based on character encoding used for telegraph data. The American National Standards Institute first published it as a standard for computing in 1963.

EBCDIC

EBCDIC stands for Extended Binary Coded Decimal Interchange Code. It is mainly used on IBM mainframe and IBM midrange computer operating systems. It is also supported by some platforms other than IBM. EBCDIC uses 8 bits to represent a single character, and it represents a 256 (2⁸) alphanumeric and special characters. There are several disadvantages to EBCDIC. When compared to ASCII, the same character which takes 7 bits to represent in ASCII will take 8 bits in EBCDIC. Therefore, EBCDIC is less efficient than ASCII.

Data Warehouse and Data Lake

2022-02-09T01:01:00.004+05:30

Data Warehouse and Data Lake in a nutshell

A Data Warehouse is used as a central storage for large amounts of structured data that might be coming from various sources.

Such stores are very important to companies as they can be used to deliver insights from across the organisation to support decision making.

On the other hand, a Data Lake is a flexible storage that is used to store unstructured, semi-structured or structured raw data. The stored data is unprocessed and the structure is usually applied when it is retrieved. Note however that a Data Lake is not a replacement for a Data Warehouse.

Which to choose

Data Warehouses and Lakes are both used by organisations as centralised data stores that enable different users and organisation units to access and use data to extract insights and perform any sort of analysis. Usually an organisation will need both a Data Lake and a Warehouse to support all the required use-cases and end users.

A data lake is capable of housing all data of any form; from structured to unstructured. Additionally, it does not require any sort of pre-processing before storing the data as this can happen once it is stored in the data lake. Data Lakes are mostly useful to Data Scientists and Engineers that require access to even unstructured data that will help them build Artificial Intelligence or Machine Learning models. Data Lakes are also more cost efficient compared to Data Warehouses as they don’t require data to have any particular format such as a schema.

Now a data warehouse is only capable of storing structured data which are ready to be analysed by specific organisation units in order to unveil business insights. Therefore, ETL processes are usually required to be built around the Data Warehouse. ETL functionality enables data to be stored in the expected format and extracted or transformed so that users can perform particular tasks over them. For that reason, Data Warehouses are very powerful for business or operations analysts that require to have access to relational data with schema that will enable them to create reports and support decision making by discovering insights.

A Final Word

In this article, we discussed the key differences between Data Lakes and Warehouses. Note though that this is not an apple-to-apple comparison.Both support different use-cases and serve different users and usually organisations require both to operate efficiently.

Data Lakes are more flexible and schema-less stores that are capable of storing unstructured, semi-structured or structured data. They are usually useful to more technical users such as Data Scientists or Engineers. On the other hand, Data Warehouses can only accept relation data which in turn is more useful to less technical people who need access to ready-for-analysis data.

Hard Disk Drive

2022-02-09T00:57:00.000+05:30

Hard drive is a non-volatile memory hardware which store all your computer’s information and data physically in it and houses the hard disk. Sometimes hard disk is also known by the terms Hard Disk Drive.

A Hard Disk Drive has a magnetic material coated plates where the information to be recorded. In contrast to sequentially addressable storage media such as magnetic tape or punched tape drives, Hard Disk Drive is a direct access storage device or DASD, as data can be accessed directly from a Hard Disk Drive.

Structure of Hard Disk Drive

Common form factors for Hard Disk Drive (the width) is 5.25 “, 3.5”, 2.5 “and 1.8” . Upto 0.85 inch Hard Disk Drive is available but usually 3.5 inch hard drive is the standard in desktop computers. A hard disk consists of one or more rotating mounted disks, one axis, also called spindle, an electric motor to rotate the disks, moving heads which read and writes the data, an IC for for controlling the motor and head, a dedicated RAM, outer very strong casing and the interfaces to attach for power supply and data exchange.

Function Of Hard Drive

The main function of hard disk is to store data for long term and data can be computer’s operating systems, applications, documents, personal files and so on. Now the main thing that need to notice that how much amount of data storage capacity hard drive have and that measured in gigabytes or terabytes. Performance refers to read and write speeds, latency, seek time. Seek and latency time measured in the time that are going to take magnetic heads in hard disk to access the data desired and the read write speed and data transfer rate are measured that how much capacity data can be written from the drive and read from a desired location in specific amount of time.

Network Model

2022-01-22T12:29:00.003+05:30

The term computer network model defines the category in which a computer network can be grouped into. Networks are divided into two broad categories:

1.Peer to peer or Workgroup Model

2.Domain based model or Client/server model

1.Peer to peer or Workgroup Model

When nodes or workstations perform the same communication functions, they are referred to as peers, in this network model, both server and client operations are performed by the same computer. Each user administers his/her workstation and the resources in it. In a peer-to-peer network, there are no dedicated servers, and there is no hierarchy among the computers. All the computers are equal and therefore are known as peers. Each computer functions as both a client and a server, and there is no administrator responsible for the entire network. The user on each computer determines which data on that computer is shared on the network.

Advantages of using peer to peer

They are easy to configure
Computers communicate easily.
They don’t require additional server hardware or software
Users can manage their own resources.
They don’t require a network administrator
They reduce total cost of network setup.

Disadvantages of using peer to peer

They provide a limited number of connections for shared resources.
Computers with shared resources suffer from sluggish performance.
They don’t allow for central management
Users are responsible for managing resources. These resources include data in shared directories, printers, fax cards, and so on.
They offer very poor security.

2.Domain based model or Client/server model

This is a network model that offers centralized access to services and devices. One computer plays the role of a server. It is the most common type of network architecture today that provides centralized data storage, security, manning of applications and network administration. Most servers operating system are Novel Netware, Windows NT, Apple talk, Linux, Banyan VINES etc…

Disadvantages

Cost: – More expensive in terms of hardware and network operating system.
Complexity: – Experienced system administrators are required to manage the systems.
Dependence: – When server goes down, operations will cease across the network.

Advantages

They are best suited for 10 or more users.
Security: – All major server based systems provides sophisticated security.
Administration: – Servers are centralized making them easier to manage.
Stability: – Server based systems are designed to support a wide range of organization sizes. Additional servers are added to increase capacity.
Client server networks offer centralized backup where data can be stored in one server.
Flexibility – New technology can be easily integrated into the system.
Accessibility – Server can be accessed remotely and across multiple platforms.

Applications of Computer

2022-01-22T11:57:00.006+05:30

There are many applications of computers and which are used in various fields.

Below are the names of the fields where the applications of a computer are used.

Education & Training centers
Business
Banking & Financial company
Entertainment
Engineering
Accounting
Communications
Digital Advertisement
Pharmacy & Hospital
Office
Library
Transporting
Gaming
CAD/CAM

Applications of Computer in Education

In the field of education too, the application of computer is being used to teach children in every school, college, the university today.

Through education applications, children are being taught in an even better way so that children are reading and understanding better. Through education applications, you can read and create digital books, digital notes. There are many applications of such education that run through the internet.

Today in every training center such as a computer training center, driving training center and many more training centers are being taught using training applications.

Applications of computer in Business

Computers are also being used in the field of business so that the business can be made more profitable and the business of businessman becomes even easier.

There are many business applications in the market today for business as well.

Through these business applications, you can completely monitor your business like - do calculations, give e-bill or paper bills to customers, do sales analyses, check price, check stock of an item, how much is left in stock now is.

Applications of computer in Banking & finance

Even in the banking sector, today all the work is being done in every bank with the use of a computer.

With the use of computers, the work of banks has become fast and convenient, due to which bank customers are also getting a lot of benefits.

Today every bank in the world is dependent on computers because every bank does its work from computers like - printing bank holder's passbook, opening new accounts, electronic fund transfers, e-banking, and many more. are done by computer. The basic work of a finance company is to give loans to its customers, before giving a loan, this company checks the credit score of that customer, after that, it decides whether to give a loan or not.

Applications of Computer in Entertainment

Computers are also being used tightly in the field of entertainment.

Today, the computer is the only means of entertainment for people around the world, due to which people never get bored and the number of people who are being entertained by computers is increasing day by day. The VLC media player is an entertainment application and there are many other types of entertainment that are given below.

YouTube
Amazon Prime
Netflix

These are all entertainment applications.

Applications of Computer in Engineering

Computers are also being widely used in the engineering sector.

Today the engineer is able to complete every one of his projects through the computer only.

Engineers used to make blueprints of their projects from sketches, which take them a lot of time, but today engineers make blueprints of their projects from computers, which saves them a lot of time.

For example, civil engineers design the map of a house, complex, mall with CAD (computer-aided design).

CAD (computer-aided design) is a 2D and 3D designing application.

Mechanical engineers also use designing applications to make model designs of vehicles.

Applications of Computer in Communication

Even in the field of communication, people are able to communicate with each other only through computer applications.

Through communication application, whenever people want to talk, they can talk to anyone.

The specialty of these applications is that it delivers your message within a few seconds from which you send the message.

These communication applications will be used by almost all the people of the world.

Through these communication applications, you can communicate with text, voice, and video.

Human Brain vs Computer

2022-01-13T20:41:00.004+05:30

Key Differences Between Brain and Computer

The brain can have 100 teraflops of memory with a density of 107 circuits per cm3 while computer memory has the 100 million megabytes with a density of 1014 bits per cm3. Memory in brain grows instantly just by connecting synaptic link whereas in a computer to scale the memory the chips need to be added.
Brain has the inbuilt backup system where the functioning pathways replace the damaged pathways. As against, backup systems are constructed manually in a computer.
The energy consumption in the brain is less than the computer.
To store information the brain uses electrochemical and electromagnetic form. Conversely, in a computer, the information is stored in the symbolic and numeric form.
In the brain, the information is transmitted with the help of chemicals to fire action potential in the neurons. On the contrary, the computer uses electrically coded signals to transmit the data.
The processing power of the brain is unlimited and provides online processing, but the brain processes information at slow speed because neurons are slow in action. In contrast, the processing power of computers is significant because of fast transistors.
The brain is self-organised while the computer is preprogrammed structure.

RISC Vs CISC

2021-10-30T11:02:00.004+05:30

BASIS FOR COMPARISON	RISC	CISC
Emphasis on	Software	Hardware
Includes	Single clock	Multi-clock
Instruction-set size	Small	Large
Instruction formats	fixed (32-bit) format	Varying formats (16-64 bits each instruction).
Addressing modes used	Limited to 3-5	12-24
General purpose registers used	32-192	8-24
Memory inferences	Register to register	Memory to memory
Cache design	Split data cache and instruction cache.	Unified cache for instructions and data.
Clock rate	50-150 MHz	33-50 MHz
Cycles Per Instruction	Single cycle for all instructions and an average CPI < 1.5.	CPI between 2 and 15.
CPU Control	Hardwired without control memory.	Micro-coded using control memory (ROM).

Master Slave Flip Flop

2021-10-09T09:36:00.005+05:30

Basically, this type of flip flop can be designed with two JK FFs by connecting in series. One of these FFs, one FF works as the master as well as other FF works as a slave. The connection of these FFs can be done like this, the master FF output can be connected to the inputs of the slave FF. Here slave FF’s outputs can be connected to the inputs of the master FF.

In this type of FF, an inverter is also used addition to two FFs. The inverter connection can be done in such a way that where the inverted CLK pulse can be connected to the slave FF. In other terms, if CLK pulse is 0 for a master FF, then CLK pulse will be 1 for a slave FF. Similarly, when CLK pulse is 1 for master FF, then CLK pulse will be 0 for slave FF.

Master-Slave FF Working

Whenever the CLK pulse goes to high which means 1, then the slave can be separated; the inputs like J & K may change the condition of the system.

The slave FF can be is detached until the CLK pulse goes to low which means to 0. Whenever the CLK pulse goes back to low-state, then the data can be transmitted from the master FF to the slave FF and finally, the o/p can be obtained.

At first, the master FF will be triggered at a positive level whereas the slave FF will be triggered at a negative level. Due to this reason, the master FF responds first.

If J=0 & K=1, then the output of the master FF ‘Q’ goes to the input K of the slave FF & the CLK forces the slave FF to RST (reset), therefore the slave FF copies the master FF.

If J=1 & K=0, then the of the master FF ‘Q’ goes to the input J of the slave FF & the CLK’s negative transition sets the slave FF, and copies the master.

If J=1 & K=1, then it toggles over the CLK’s positive transition & therefore the slave toggles over the CLK’s negative transition.

If both the J & K are 0, then the FF can be immobilized & Q remains unmovable.

BCA 1ST YEAR Previous year Question

2021-08-26T16:38:00.003+05:30

Career Awareness Session

2021-08-19T10:52:00.006+05:30

Please fill the form for attend the online session.

https://forms.gle/4ZAXgn3AQnzfZc4h7

SCANNERS

2021-07-07T10:06:00.001+05:30

A scanner is a device that captures images from photographic prints, posters, magazine pages, and similar sources for computer editing and display. Scanners come in hand-held, feed-in, and flatbed types and for scanning black-and-white only, or color.

HOW SCANNERS WORK
Scanners operate by shining light at the object or document being digitized and directing the reflected light (usually through a series of mirrors and lenses) onto a photosensitive element. In most scanners, the sensing medium is an electronic, light-sensing integrated circuit known as a charged coupled device (CCD). Light-sensitive photosites arrayed along the CCD convert levels of brightness into electronic signals that are then processed into a digital image.

A scanner consists of a flat transparent glass bed under which the CCD sensors, lamp, lenses, filters and also mirrors are fixed. The document has to be placed on the glass bed. There will also be a cover to close the scanner. This cover may either be white or black in colour. This colour helps in providing uniformity in the background. This uniformity will help the scanner software to determine the size of the document to be scanned.

The lamp brightens up the text to be scanned. Most scanners use a cold cathode fluorescent lamp (CCFL).

A stepper motor under the scanner moves the scanner head from one end to the other. The movement will be slow and is controlled by a belt. The scanner head consists of the mirrors, lens, CCD sensors and also the filter. The scan head moves parallel to the glass bed and that too in a constant path. As deviation may occur in its motion, a stabilizer bar will be provided to compromise it. The scan head moves from one end of the machine to the other. When it has reached the other end the scanning of the document has been completed. For some scanners, a two way scan is used in which the scan head has to reach its original position to ensure a complete scan.

As the scan head moves under the glass bed, the light from the lamp hits the document and is reflected back with the help of mirrors angled to one another. According to the design of the device there may be either 2-way mirrors or 3-way mirrors. The mirrors will be angled in such a way that the reflected image will be hitting a smaller surface. In the end, the image will reach a lens which passes it through a filter and causes the image to be focussed on CCD sensors. The CCD sensors convert the light to electrical signals according to its intensity. Take a look at the diagram given below.

The electrical signals will be converted into image format inside a computer. This reception may also differ according to the variation in the lens and filter design. A method called three pass scanning is commonly used in which each movement of the scan head from one end to another uses each composite colour to be passed between the lens and the CCD sensors. After the three composite colours are scanned, the scanner software assembles the three filtered images into one single -colour image.

Digitizer, stylus, Accelerometer and Gyroscope

2021-06-30T08:42:00.004+05:30

A digitizer is a hardware device that receives analog information, such as sound or light, and records it digitally. Usually, the information is stored in a file on a computing device. This process is called digitization.

For example, a digital camera is a digitizer. Light enters through the camera lens, and the hardware and software inside the camera converts that information to binary data, and stores it an image file. The user may then transfer the file to a computer, where he or she can edit the image, print it out, or share it online.

Examples of digitizers

A digital camera is one example of a digitizer. Other examples include:

Audio digitizer

Most computers have a microphone jack, where you can connect an analog microphone. The analog input (the audio signal) is processed in the computer by a discrete sound card, or by audio hardware on the motherboard itself. This data can then be used by software running on the computer. Some audio digitizers are small hand-held devices, and some are expensive peripherals that provide professional-level conversion quality. The microphone in a smartphone is another audio digitizer.

Digital Tablet

A tablet is a computing device that is controlled with a finger or a digital pen called a stylus. A tablet is usually larger than a smartphone, but smaller than a computer monitor. Some tablets have a screen, which is touched directly, and some tablets are peripheral devices, without screens, which attach to a computer. The user can write, draw, and paint by touching the tablet. Software converts the analog touch input to lines or pressure-sensitive brush strokes in a document. The software may also perform handwriting recognition to convert handwritten text to typewritten words. When dealing with graphics these tablets are often referred to as a graphics tablet.

Accelerometer and gyroscope

Digitizers inside smartphones and tablet computers can detect how fast the device is moving (an accelerometer), and the angle it's held (a gyroscope). The analog information of motion and angular rotation is converted to data your apps can use in real time. For example, using a gyroscope, a smartphone could be held up to the sky to receive information about the position of stars and planets. The accelerometer helps reduce motion blur when you're taking a photo, and can trigger safety mechanisms if the device is accidentally dropped.

MAC Address

2021-06-26T11:59:00.005+05:30

A MAC (Media Access Control) address is a 48 bit unique ID assigned to every internet-connected machine that allows it to be identified when connected to a specific network. Also known as Hardware Address or physical address of machine on network.

A MAC address is a hardware identification number that uniquely identifies each device on a network. The MAC address is manufactured into every network card, such as an Ethernet card or Wi-Fi card, and therefore cannot be changed.

MAC is divided into The vendor ID (24 bit) and other NIC identifier 24 bit.

Because there are millions of networkable devices in existence, and each device needs to have a unique MAC address, there must be a very wide range of possible addresses. For this reason, MAC addresses are made up of six two-digit hexadecimal numbers, separated by colons. For example, an Ethernet card may have a MAC address of 00:0d:83:b1:c0:8e. Fortunately, you do not need to know this address, since it is automatically recognized by most networks.

Finding Your MAC Address

windows

Click Start then Run (in Windows 7, Start and type in the Search Programs and Files box.)
Enter: cmd
Enter: ipconfig /all
If the output scrolls off your screen, and it will on Vista and Windows 7, use: ipconfig /all | more
The Physical Address is your MAC address; it will look like 00-15-E9-2B-99-3C. You will have a physical address for each network connection that you have.

Linux

Become root, using su.

Enter: ifconfig -a

# ifconfig -a
eth0      Link encap:Ethernet  HWaddr 00:09:3D:12:33:33  
          inet addr:10.248.155.17  Bcast:10.248.255.255  Mask:255.255.0.0
          inet6 addr: fe50::234:3dff:fe12:7d73/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:3489041718 errors:0 dropped:0 overruns:0 frame:0
          TX packets:3259212142 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:2732221481 (2.5 GiB)  TX bytes:4065716672 (3.7 GiB)
          Interrupt:185

The ethernet devices are called eth0, eth1, and so on The MAC address is in the first line of the output, labeled HWaddr, it is 00:09:3D:12:33:33.

UNIX -- An INTRODUCTION

2021-06-19T12:17:00.006+05:30

What Is UNIX?

UNIX is an operating system developed in the Bell Laboratories AT&T and is an example a multi-tasking, multi-user operating system. It provides its users with: program development tools; electronic communications facilities, such as an electronic mail; text editors and text formatters. There are also many development tools available as standard within the UNIX operating system that other operating systems require as add-ons.

UNIX is an operating system which was first developed in the 1960s, and has been under constant development ever since. By operating system, we mean the suite of programs which make the computer work. It is a stable, multi-user, multi-tasking system for servers, desktops and laptops.

UNIX systems also have a graphical user interface (GUI) similar to Microsoft Windows which provides an easy to use environment. However, knowledge of UNIX is required for operations which aren't covered by a graphical program, or for when there is no windows interface available, for example, in a telnet session.

Types of UNIX

There are many different versions of UNIX, although they share common similarities. The most popular varieties of UNIX are Sun Solaris, GNU/Linux, and MacOS X.

Operating System Notes Part 2 PDF

2021-06-19T12:11:00.005+05:30

OS NOTES PART 5

OS NOTES PART 6

OS NOTES PART 7

OS NOTES PART 8

OS NOTES PART 9

OS NOTES PART 1 0

OS NOTES P revious

Basic Electronics PDF

2021-06-18T13:29:00.001+05:30

Basic Electronics PDF 1

Basic Electronics PDF 2

Basic Electronics PDF 3

TYPES OF INTERNET CONNECTIONS

2021-06-18T13:25:00.003+05:30

DIAL UP CONNECTION: Dial-up Internet access is a form of Internet access that uses the facilities of the public switched telephone network (PSTN) to establish a connection to an Internet service provider (ISP) by dialing a telephone number on a conventional telephone line.
This type of connection is called dial-up because the initiating device, usually an Internet user's personal computer, will literally pick up the telephone line signal and dial up the telephone number of a receiving device, usually an Internet-connected modem.
The condition of the telephone line has a lot to do with the maximum speed of the dial up connection. Under optimal circumstances, a 56kbps throughput can be maintained. Real world speeds typically vary between 18kbps and 48kbps.

Broadband Connections:

The term broadband commonly refers to high-speed Internet access that is always on and faster than the traditional dial-up access. Broadband includes several high-speed transmission technologies such as:

Digital Subscriber Line (DSL)
Cable Modem
Fiber
Wireless
Satellite
Broadband over Powerlines (BPL)

The broadband technology you choose will depend on a number of factors. These may include whether you are located in an urban or rural area, how broadband Internet access is packaged with other services (such as voice telephone and home entertainment), price, and availability.

Digital Subscriber Line (DSL)

DSL is a wireline transmission technology that transmits data faster over traditional copper telephone lines already installed to homes and businesses. DSL-based broadband provides transmission speeds ranging from several hundred Kbps to millions of bits per second (Mbps). The availability and speed of your DSL service may depend on the distance from your home or business to the closest telephone company facility.

The following are types of DSL transmission technologies:

Asymmetrical Digital Subscriber Line (ADSL) – Used primarily by residential customers, such as Internet surfers, who receive a lot of data but do not send much. ADSL typically provides faster speed in the downstream direction than the upstream direction. ADSL allows faster downstream data transmission over the same line used to provide voice service, without disrupting regular telephone calls on that line.
Symmetrical Digital Subscriber Line (SDSL) – Used typically by businesses for services such as video conferencing, which need significant bandwidth both upstream and downstream.

Faster forms of DSL typically available to businesses include:

High data rate Digital Subscriber Line (HDSL); and
Very High data rate Digital Subscriber Line (VDSL).

Cable Modem

Cable modem service enables cable operators to provide broadband using the same coaxial cables that deliver pictures and sound to your TV set.

Most cable modems are external devices that have two connections: one to the cable wall outlet, the other to a computer. They provide transmission speeds of 1.5 Mbps or more.

Subscribers can access their cable modem service by simply turning on their computers, without dialing-up an ISP. You can still watch cable TV while using it. Transmission speeds vary depending on the type of cable modem, cable network, and traffic load. Speeds are comparable to DSL.

Fiber

Fiber optic technology converts electrical signals carrying data to light and sends the light through transparent glass fibers about the diameter of a human hair. Fiber transmits data at speeds far exceeding current DSL or cable modem speeds, typically by tens or even hundreds of Mbps.
The actual speed you experience will vary depending on a variety of factors, such as how close to your computer the service provider brings the fiber and how the service provider configures the service, including the amount of bandwidth used. The same fiber providing your broadband can also simultaneously deliver voice (VoIP) and video services, including video-on-demand.
Telecommunications providers sometimes offer fiber broadband in limited areas and have announced plans to expand their fiber networks and offer bundled voice, Internet access, and video services.
Variations of the technology run the fiber all the way to the customer’s home or business, to the curb outside, or to a location somewhere between the provider’s facilities and the customer.

Wireless

Wireless broadband connects a home or business to the Internet using a radio link between the customer’s location and the service provider’s facility. Wireless broadband can be mobile or fixed.
Wireless technologies using longer-range directional equipment provide broadband service in remote or sparsely populated areas where DSL or cable modem service would be costly to provide. Speeds are generally comparable to DSL and cable modem. An external antenna is usually required.
Wireless broadband Internet access services offered over fixed networks allow consumers to access the Internet from a fixed point while stationary and often require a direct line-of-sight between the wireless transmitter and receiver. These services have been offered using both licensed spectrum and unlicensed devices. For example, thousands of small Wireless Internet Services Providers (WISPs) provide such wireless broadband at speeds of around one Mbps using unlicensed devices, often in rural areas not served by cable or wireline broadband networks.
Wireless Local Area Networks (WLANs) provide wireless broadband access over shorter distances and are often used to extend the reach of a "last-mile" wireline or fixed wireless broadband connection within a home, building, or campus environment. Wi-Fi networks use unlicensed devices and can be designed for private access within a home or business, or be used for public Internet access at "hot spots" such as restaurants, coffee shops, hotels, airports, convention centers, and city parks.
Mobile wireless broadband services are also becoming available from mobile telephone service providers and others. These services are generally appropriate for highly-mobile customers and require a special PC card with a built in antenna that plugs into a user’s laptop computer. Generally, they provide lower speeds, in the range of several hundred Kbps.

Satellite

Just as satellites orbiting the earth provide necessary links for telephone and television service, they can also provide links for broadband. Satellite broadband is another form of wireless broadband, and is also useful for serving remote or sparsely populated areas.

Downstream and upstream speeds for satellite broadband depend on several factors, including the provider and service package purchased, the consumer’s line of sight to the orbiting satellite, and the weather. Typically a consumer can expect to receive (download) at a speed of about 500 Kbps and send (upload) at a speed of about 80 Kbps. These speeds may be slower than DSL and cable modem, but they are about 10 times faster than the download speed with dial-up Internet access. Service can be disrupted in extreme weather conditions.

Broadband over Powerline (BPL)

BPL is the delivery of broadband over the existing low- and medium-voltage electric power distribution network. BPL speeds are comparable to DSL and cable modem speeds. BPL can be provided to homes using existing electrical connections and outlets. BPL is an emerging technology that is available in very limited areas. It has significant potential because power lines are installed virtually everywhere, alleviating the need to build new broadband facilities for every customer.

VSAT (Very Small Aperture Terminal)

2021-06-18T13:14:00.003+05:30

VSAT stands for “Very Small Aperture Terminal” and refers to receive/transmit terminals installed at dispersed sites connecting to a central hub via satellite using small diameter antenna dishes (.75 to 3.8 meter).
VSAT technology represents a cost effective solution for users seeking an independent communications network connecting a large number of geographically dispersed sites. VSAT networks offer value-added satellite-based services capable of supporting the Internet, LAN, voice/fax communications, video, security, and provide powerful, dependable private and public network communications solutions.
Generally, these systems operate in the Ku-band and C-band frequencies, and soon Ka-band. Ku-band based networks are used primarily in Europe and North America and utilize the smaller sizes of VSAT antennas. C-band, used extensively in Asia, Africa and Latin America, require larger antenna sizes. These are quite common in Cyber Cafes throughout the rest of the world.

VSAT networks can be configured to receive only or transmit and receive. Examples of uses we commonly see for receive only are:

• Stock market & other news broadcasting
• Training or continuing education from a distance
• Distribute financial trends & analyses
• Introduce new products at geographically dispersed locations
• Update market related data, news, and catalog prices
• Distribute video or TV programs (Directv and DISH)
• Distribute music in stores & public areas
• Relay advertising to electronic signs in retail stores.
Examples of uses we see for receive/transmit are:
• Interactive computer transactions
• Internet
• Distance Learning Video Teleconferencing
• Database inquiries
• Bank transactions, ATM
• Reservation systems
• Distributed remote process control and telemetry
• VoIP communications
• Airport flight and weather data
• Emergency services
• Electronic fund transfer at Point-of-Sale
• E-mail
• Medical data transfer
• Sales monitoring & stock control
• Surveillance and monitoring.
VSAT networks come in various shapes and sizes ranging from point-to-point, point-to-multipoint, and customized private hubs for thousands of sites. Mesh systems have traditionally been somewhat smaller in size than star systems—5 to 30 sites is a good rule of thumb.

Fundamentals Notes

2021-06-11T11:19:00.003+05:30

Generation of Computers, etc

Fundamentals Notes

Differences between Virtual Circuits and Datagram Networks

2021-06-10T12:15:00.004+05:30

Differences between Virtual Circuits and Datagram Networks

Virtual Circuits	Datagram Networks
Virtual circuits are connection-oriented, which means that there is a reservation of resources like buffers, bandwidth, etc. for the time during which the newly setup VC is going to be used by a data transfer session.	It is connectionless service. There is no need for reservation of resources as there is no dedicated path for a connection session.
A virtual circuit network uses a fixed path for a particular session, after which it breaks the connection and another path has to be set up for the next the next session.	A Datagram based network is a true packet switched network. There is no fixed path for transmitting data.
All the packets follow the same path and hence a global header is required only for the first packet of connection and other packets will not require it.	Every packet is free to choose any path, and hence all the packets must be associated with a header containing information about the source and the upper layer data.
Packets reach in order to the destination as data follows the same path.	Data packets reach the destination in random order, which means they need not reach in the order in which they were sent out.
Virtual Circuits are highly reliable.	Datagram networks are not as reliable as Virtual Circuits.
Implementation of virtual circuits is costly as each time a new connection has to be set up with reservation of resources and extra information handling at routers.	But it is always easy and cost-efficient to implement datagram networks as there is no need of reserving resources and making a dedicated path each time an application has to communicate.

Operating System Notes PART 1 PDF

2021-06-03T21:17:00.006+05:30

Computer Fundamentals PDF 3

2021-06-02T12:08:00.002+05:30

Computer Fundamentals PDF Notes 2

2021-06-02T12:06:00.001+05:30