Steve Jobs

Steve Jobs started his career as Co-founder of Apple in 1976.By his introduction of Apple -2 and Macintosh computers, he democratized computers i.e. can be used by any person who knows basic computer languages, much user friendly. Later he was out of Apple in 1985.Again he was back in Apple in 1997 as an Interim- CEO.This was the first step forward of Steve to save Apple from bankruptcy and reported losses of $700mn. Within two years as Interim -CEO, Steve changed the strategies of product lines and introduced iMac, Mac G3 tower and Wi-Fi product; turned around Apple and gained back its old legacy.
Career Outlook


Career of Steve Jobs was like a roller coaster ride with full of excitement and a dream to achieve heights in making a world’s best computer. Jobs in 1974 was desperately in need of money and took a job at Atari; known to be a first video gaming company making pinball machines, started by Bushnell. When he was at Atari, he made a trip to India to meet a baba for enlightenment, but returned disappointed. In 1974, Steve worked for Atari and his high school friend Woz was working for HP; and both of them attended Homebrew, a computer hobbyists club. Steve found the potential and got interested in homemade computer of Woz, thought that computer is essential to run software programs. Finally, they planned to assemble the computers themselves and sell the whole board at Homebrew meetings. Therefore, in 1976, Steve and Woz started Apple Computer Co; the name was suggested by Jobs after visiting an “apple orchard”. To get 1,000 dollars required to make the first computer board, Jobs sold his Volkswagen van and Woz his HP 65 calculator. Both the friends shared 45% of shares of the company each and remaining 10% was given to Ron Wayne ,Job’s friend at Atari; who helped them for paperwork to start the company and drew the logo for the company.
 
More about Steve Jobs


Born: Steven Paul Jobs February 24, 1955 San Francisco, California, U.S.

Died: COctober 5, 2011 (aged 56) Palo Alto, California, U.S.

Nationality: American

Alma mater: Reed College (Dropped out after one semester in 1972)

Occupation: Co-founder and CEO, Apple Inc (1974-2011)

Religion: Buddhism

Board member of: The Walt Disney Company, Apple Inc.

Marital Status: Married

Children: 3 daughters and 1 son

Megabytes, Gigabytes, Terabytes… What Are They?

Megabytes, Gigabytes, Terabytes… What Are They?

These terms are usually used in the world of computing to describe disk space, or data storage space, and system memory. For instance, just a few years ago we were describing hard drive space using the term Megabytes. Today, Gigabytes is the most common term being used to describe the size of a hard drive. In the not so distant future, Terabyte will be a common term. But what are they? This is where it gets quite confusing because there are at least three accepted definitions of each term.

According to the IBM Dictionary of computing, when used to describe disk storage capacity, a megabyte is 1,000,000 bytes in decimal notation. But when the term megabyte is used for real and virtual storage, and channel volume, 2 to the 20th power or 1,048,576 bytes is the appropriate notation. According to the Microsoft Press Computer Dictionary, a megabyte means either 1,000,000 bytes or 1,048,576 bytes. According to Eric S. Raymond in The New Hacker's Dictionary, a megabyte is always 1,048,576 bytes on the argument that bytes should naturally be computed in powers of two. So which definition do most people conform to?

When referring to a megabyte for disk storage, the hard drive manufacturers use the standard that a megabyte is 1,000,000 bytes. This means that when you buy an 80 Gigabyte Hard drive you will get a total of 80,000,000,000 bytes of available storage. This is where it gets confusing because Windows uses the 1,048,576 byte rule so when you look at the Windows drive properties an 80 Gigabyte drive will report a capacity of 74.56 Gigabytes and a 250 Gigabyte drive will only yield 232 Gigabytes of available storage space. Anybody confused yet? With three accepted definitions, there will always be some confusion so I will try to simplify the definitions a little.

The 1000 can be replaced with 1024 and still be correct using the other acceptable standards. Both of these standards are correct depending on what type of storage you are referring.

Processor or Virtual Storage	Disk Storage
· 1 Bit = Binary Digit · 8 Bits = 1 Byte · 1024 Bytes = 1 Kilobyte · 1024 Kilobytes = 1 Megabyte · 1024 Megabytes = 1 Gigabyte · 1024 Gigabytes = 1 Terabyte · 1024 Terabytes = 1 Petabyte · 1024 Petabytes = 1 Exabyte · 1024 Exabytes = 1 Zettabyte · 1024 Zettabytes = 1 Yottabyte · 1024 Yottabytes = 1 Brontobyte · 1024 Brontobytes = 1 Geopbyte	· 1 Bit = Binary Digit · 8 Bits = 1 Byte · 1000 Bytes = 1 Kilobyte · 1000 Kilobytes = 1 Megabyte · 1000 Megabytes = 1 Gigabyte · 1000 Gigabytes = 1 Terabyte · 1000 Terabytes = 1 Petabyte · 1000 Petabytes = 1 Exabyte · 1000 Exabytes = 1 Zettabyte · 1000 Zettabytes = 1 Yottabyte · 1000 Yottabytes = 1 Brontobyte · 1000 Brontobytes = 1 Geopbyte

This is based on the IBM Dictionary of computing method to describe disk storage - the simplest.

Now let's go into a little more detail.

Bit: A Bit is the smallest unit of data that a computer uses. It can be used to represent two states of information, such as Yes or No.

Byte: A Byte is equal to 8 Bits. A Byte can represent 256 states of information, for example, numbers or a combination of numbers and letters. 1 Byte could be equal to one character. 10 Bytes could be equal to a word. 100 Bytes would equal an average sentence.

Kilobyte: A Kilobyte is approximately 1,000 Bytes, actually 1,024 Bytes depending on which definition is used. 1 Kilobyte would be equal to this paragraph you are reading, whereas 100 Kilobytes would equal an entire page.

Megabyte: A Megabyte is approximately 1,000 Kilobytes. In the early days of computing, a Megabyte was considered to be a large amount of data. These days with a 500 Gigabyte hard drive on a computer being common, a Megabyte doesn't seem like much anymore. One of those old 3-1/2 inch floppy disks can hold 1.44 Megabytes or the equivalent of a small book. 100 Megabytes might hold a couple volumes of Encyclopedias. 600 Megabytes is about the amount of data that will fit on a CD-ROM disk.

Gigabyte: A Gigabyte is approximately 1,000 Megabytes. A Gigabyte is still a very common term used these days when referring to disk space or drive storage. 1 Gigabyte of data is almost twice the amount of data that a CD-ROM can hold. But it's about one thousand times the capacity of a 3-1/2 floppy disk. 1 Gigabyte could hold the contents of about 10 yards of books on a shelf. 100 Gigabytes could hold the entire library floor of academic journals.

Terabyte: A Terabyte is approximately one trillion bytes, or 1,000 Gigabytes. There was a time that I never thought I would see a 1 Terabyte hard drive, now one and two terabyte drives are the normal specs for many new computers.  To put it in some perspective, a Terabyte could hold about 3.6 million 300 Kilobyte images or maybe about 300 hours of good quality video. A Terabyte could hold 1,000 copies of the Encyclopedia Britannica. Ten Terabytes could hold the printed collection of the Library of Congress. That's a lot of data.

Petabyte: A Petabyte is approximately 1,000 Terabytes or one million Gigabytes. It's hard to visualize what a Petabyte could hold. 1 Petabyte could hold approximately 20 million 4-door filing cabinets full of text. It could hold 500 billion pages of standard printed text. It would take about 500 million floppy disks to store the same amount of data.

Exabyte: An Exabyte is approximately 1,000 Petabytes. Another way to look at it is that an Exabyte is approximately one quintillion bytes or one billion Gigabytes. There is not much to compare an Exabyte to. It has been said that 5 Exabytes would be equal to all of the words ever spoken by mankind.

Zettabyte: A Zettabyte is approximately 1,000 Exabytes. There is nothing to compare a Zettabyte to but to say that it would take a whole lot of ones and zeroes to fill it up.

Yottabyte: A Yottabyte is approximately 1,000 Zettabytes. It would take approximately 11 trillion years to download a Yottabyte file from the Internet using high-power broadband. You can compare it to the World Wide Web as the entire Internet almost takes up about a Yottabyte.

Brontobyte: A Brontobyte is (you guessed it) approximately 1,000 Yottabytes. The only thing there is to say about a Brontobyte is that it is a 1 followed by 27 zeroes!

Geopbyte: A Geopbyte is about 1000 Brontobytes! Not sure why this term was created. I'm doubting that anyone alive today will ever see a Geopbyte hard drive. One way of looking at a geopbyte is 1₅267 650₄600 228₃229 401₂496 703₁205 376 bytes!

Now you should have a good understanding of megabytes, gigabytes, terabytes and everything in between. Now if we can just figure out what a WhatsAByte is......:)

http://www.godwindinesh.blogspot.com/

This Post  published  by

S.G.Godwin Dinesh MCA

Next Generation of IPv6

Next Generation of IPv6

       The world will soon have a new internet. Each device connected to the World Wide Web is identified through a unique number, similar to a phone number, called the internet protocol (IP) address.

       A 32 – bit identifier, the internet protocol version 4 (IPv4), has been in use since 1981. Now the numbers are running out.

             For example, a typical Ipv4 address would look like this: 

                        192.168.1.165

        On February 1, the internet assigned numbers authority assigned the last batch of IPv4 addresses. Most countries are now gearing to shift to the next generation of IP.

       IPv6 is a 128 – bit protocol, offering a vastly expanded address space. The shift to a new version is akin to Indian telephone operators converting their landline numbering scheme from 6 digits to 8 digits so as to accommodate more subscribers. This shift, which is inevitable due to the rapid growth of the internet, will require both hardware as well as software upgrade.

         For example, a typical Ipv6 address would look like this:

               3ffe:0501:0008:0000:0260:97ff:fe40: efab

           Such an address will require eight slots, whereas most devices and associated software that exist today have only four slots.

            The existing pool of IP address allocated to the Asia pacific region will run out sometime in 2012, says S.G.Godwin Dinesh, a executive in the network information centre in Blessing InfoTech limited. This is the regional internet registry for the Asia pacific region. However, unlike countries like Japan that have made 75 percent of their networks IPv6-ready, the situation in India is quite alarming.

          Only five to six percent of networks in India have deployed IPv6 compatibles equipment. Network elements such as routers, switches and servers must be upgraded immediately to be able to communicate with IPv6 networks or else the Inter – web will become fragmented. Indian internet users would just be able to access some portions of the Internet,”Mr. Godwin Dinesh says.

       He says the residential user need not panic as their Operating System (OS) will definitely be IPv6-compatible, and they will be alerted by their Internet Service Provider (ISP) if a modem upgrade is required. “Corporates and medium enterprises will face a major challenge as they must also start installing translation engines to achieve inter-operability between IPv4 and IPv6.
       The Internet Service Providers Association of India, says the government has prepared a road map to make all networks IPv6-compatible, but it will have to start by putting official websites, banks and railway booking sites on the IPv6 network.”

       As part of the road map, a national internet registry will soon be set up. It claims ISP’s have not migrated their customers “owing to the absence of content.” Also we cannot just scrap all IPv4 equipment. Migration requires some investment, and it can only be done by the government.”

Published Author

Godwin Dinesh

                                                                                               

Networking Concepts

Networking concepts



1. What are the two types of transmission technology available?

(i) Broadcast and (ii) point-to-point



2. What is subnet?

A generic term for section of a large networks usually separated by a bridge or router.



3. Difference between the communication and transmission.

Transmission is a physical movement of information and concern issues like bit polarity, synchronisation, clock etc.

Communication means the meaning full exchange of information between two communication media.



4. What are the possible ways of data exchange?

(i) Simplex (ii) Half-duplex (iii) Full-duplex.



5. What is SAP?

Series of interface points that allow other computers to communicate with the other layers of network protocol stack.



6. What do you meant by "triple X" in Networks?

The function of PAD (Packet Assembler Disassembler) is described in a document known as X.3. The standard protocol has been defined between the terminal and the PAD, called X.28; another standard protocol exists between hte PAD and the network, called X.29. Together, these three recommendations are often called "triple X"



7. What is frame relay, in which layer it comes?

Frame relay is a packet switching technology. It will operate in the data link layer.



8. What is terminal emulation, in which layer it comes?

Telnet is also called as terminal emulation. It belongs to application layer.



9. What is Beaconing?

The process that allows a network to self-repair networks problems. The stations on the network notify the other stations on the ring when they are not receiving the transmissions. Beaconing is used in Token ring and FDDI networks.



10. What is redirector?

Redirector is software that intercepts file or prints I/O requests and translates them into network requests. This comes under presentation layer.



11. What is NETBIOS and NETBEUI?

NETBIOS is a programming interface that allows I/O requests to be sent to and received from a remote computer and it hides the networking hardware from applications.

NETBEUI is NetBIOS extended user interface. A transport protocol designed by microsoft and IBM for the use on small subnets.



12. What is RAID?

A method for providing fault tolerance by using multiple hard disk drives.



13. What is passive topology?

When the computers on the network simply listen and receive the signal, they are referred to as passive because they don’t amplify the signal in any way. Example for passive topology - linear bus.



14. What is Brouter?

Hybrid devices that combine the features of both bridges and routers.



15. What is cladding?

A layer of a glass surrounding the center fiber of glass inside a fiber-optic cable.



16. What is point-to-point protocol

A communications protocol used to connect computers to remote networking services including Internet service providers.



17. How Gateway is different from Routers?

A gateway operates at the upper levels of the OSI model and translates information between two completely different network architectures or data formats



18. What is attenuation?

The degeneration of a signal over distance on a network cable is called attenuation.



19. What is MAC address?

The address for a device as it is identified at the Media Access Control (MAC) layer in the network architecture. MAC address is usually stored in ROM on the network adapter card and is unique.



20. Difference between bit rate and baud rate.

Bit rate is the number of bits transmitted during one second whereas baud rate refers to the number of signal units per second that are required to represent those bits.

baud rate = bit rate / N

where N is no-of-bits represented by each signal shift.



21. What is Bandwidth?

Every line has an upper limit and a lower limit on the frequency of signals it can carry. This limited range is called the bandwidth.



22. What are the types of Transmission media?

Signals are usually transmitted over some transmission media that are broadly classified in to two categories.

a) Guided Media:

These are those that provide a conduit from one device to another that include twisted-pair, coaxial cable and fiber-optic cable. A signal traveling along any of these media is directed and is contained by the physical limits of the medium. Twisted-pair and coaxial cable use metallic that accept and transport signals in the form of electrical current. Optical fiber is a glass or plastic cable that accepts and transports signals in the form of light.

b) Unguided Media:

This is the wireless media that transport electromagnetic waves without using a physical conductor. Signals are broadcast either through air. This is done through radio communication, satellite communication and cellular telephony.



23. What is Project 802?

It is a project started by IEEE to set standards to enable intercommunication between equipment from a variety of manufacturers. It is a way for specifying functions of the physical layer, the data link layer and to some extent the network layer to allow for interconnectivity of major LAN

protocols.

It consists of the following:

 802.1 is an internetworking standard for compatibility of different LANs and MANs across protocols.

 802.2 Logical link control (LLC) is the upper sublayer of the data link layer which is non-architecture-specific, that is remains the same for all IEEE-defined LANs.

 Media access control (MAC) is the lower sublayer of the data link layer that contains some distinct modules each carrying proprietary information specific to the LAN product being used. The modules are Ethernet LAN (802.3), Token ring LAN (802.4), Token bus LAN (802.5).

 802.6 is distributed queue dual bus (DQDB) designed to be used in MANs.



24. What is Protocol Data Unit?

The data unit in the LLC level is called the protocol data unit (PDU). The PDU contains of four fields a destination service access point (DSAP), a source service access point (SSAP), a control field and an information field. DSAP, SSAP are addresses used by the LLC to identify the protocol stacks on the receiving and sending machines that are generating and using the data. The control field specifies whether the PDU frame is a information frame (I - frame) or a supervisory frame (S - frame) or a unnumbered frame (U - frame).



25. What are the different type of networking / internetworking devices?

Repeater:

Also called a regenerator, it is an electronic device that operates only at physical layer. It receives the signal in the network before it becomes weak, regenerates the original bit pattern and puts the refreshed copy back in to the link.

Bridges:

These operate both in the physical and data link layers of LANs of same type. They divide a larger network in to smaller segments. They contain logic that allow them to keep the traffic for each segment separate and thus are repeaters that relay a frame only the side of the segment containing the intended recipent and control congestion.

Routers:

They relay packets among multiple interconnected networks (i.e. LANs of different type). They operate in the physical, data link and network layers. They contain software that enable them to determine which of the several possible paths is the best for a particular transmission.

Gateways:

They relay packets among networks that have different protocols (e.g. between a LAN and a WAN). They accept a packet formatted for one protocol and convert it to a packet formatted for another protocol before forwarding it. They operate in all seven layers of the OSI model.



26. What is ICMP?

ICMP is Internet Control Message Protocol, a network layer protocol of the TCP/IP suite used by hosts and gateways to send notification of datagram problems back to the sender. It uses the echo test / reply to test whether a destination is reachable and responding. It also handles both control and error messages.



27. What are the data units at different layers of the TCP / IP protocol suite?

The data unit created at the application layer is called a message, at the transport layer the data unit created is called either a segment or an user datagram, at the network layer the data unit created is called the datagram, at the data link layer the datagram is encapsulated in to a frame and finally transmitted as signals along the transmission media.



28. What is difference between ARP and RARP?

The address resolution protocol (ARP) is used to associate the 32 bit IP address with the 48 bit physical address, used by a host or a router to find the physical address of another host on its network by sending a ARP query packet that includes the IP address of the receiver.

The reverse address resolution protocol (RARP) allows a host to discover its Internet address when it knows only its physical address.



29. What is the minimum and maximum length of the header in the TCP segment and IP datagram?

The header should have a minimum length of 20 bytes and can have a maximum length of 60 bytes.



30. What is the range of addresses in the classes of internet addresses?

Class A 0.0.0.0 - 127.255.255.255

Class B 128.0.0.0 - 191.255.255.255

Class C 192.0.0.0 - 223.255.255.255

Class D 224.0.0.0 - 239.255.255.255

Class E 240.0.0.0 - 247.255.255.255



31. What is the difference between TFTP and FTP application layer protocols?

The Trivial File Transfer Protocol (TFTP) allows a local host to obtain files from a remote host but does not provide reliability or security. It uses the fundamental packet delivery services offered by UDP.

The File Transfer Protocol (FTP) is the standard mechanism provided by TCP / IP for copying a file from one host to another. It uses the services offer by TCP and so is reliable and secure. It establishes two connections (virtual circuits) between the hosts, one for data transfer and another for control information.



32. What are major types of networks and explain?

 Server-based network

 Peer-to-peer network

Peer-to-peer network, computers can act as both servers sharing resources and as clients using the resources.

Server-based networks provide centralized control of network resources and rely on server computers to provide security and network administration



33. What are the important topologies for networks?

 BUS topology:

In this each computer is directly connected to primary network cable in a single line.

Advantages:

Inexpensive, easy to install, simple to understand, easy to extend.



 STAR topology:

In this all computers are connected using a central hub.

Advantages:

Can be inexpensive, easy to install and reconfigure and easy to trouble shoot physical problems.



 RING topology:

In this all computers are connected in loop.

Advantages:

All computers have equal access to network media, installation can be simple, and signal does not degrade as much as in other topologies because each computer regenerates it.



34. What is mesh network?

A network in which there are multiple network links between computers to provide multiple paths for data to travel.



35. What is difference between baseband and broadband transmission?

In a baseband transmission, the entire bandwidth of the cable is consumed by a single signal. In broadband transmission, signals are sent on multiple frequencies, allowing multiple signals to be sent simultaneously.



36. Explain 5-4-3 rule?

In a Ethernet network, between any two points on the network ,there can be no more than five network segments or four repeaters, and of those five segments only three of segments can be populated.



37. What MAU?

In token Ring , hub is called Multistation Access Unit(MAU).



38. What is the difference between routable and non- routable protocols?

Routable protocols can work with a router and can be used to build large networks. Non-Routable protocols are designed to work on small, local networks and cannot be used with a router



39. Why should you care about the OSI Reference Model?

It provides a framework for discussing network operations and design.



40. What is logical link control?

One of two sublayers of the data link layer of OSI reference model, as defined by the IEEE 802 standard. This sublayer is responsible for maintaining the link between computers when they are sending data across the physical network connection.



41. What is virtual channel?

Virtual channel is normally a connection from one source to one destination, although multicast connections are also permitted. The other name for virtual channel is virtual circuit.



42. What is virtual path?

Along any transmission path from a given source to a given destination, a group of virtual circuits can be grouped together into what is called path.



43. What is packet filter?

Packet filter is a standard router equipped with some extra functionality. The extra functionality allows every incoming or outgoing packet to be inspected. Packets meeting some criterion are forwarded normally. Those that fail the test are dropped.



44. What is traffic shaping?

One of the main causes of congestion is that traffic is often busy. If hosts could be made to transmit at a uniform rate, congestion would be less common. Another open loop method to help manage congestion is forcing the packet to be transmitted at a more predictable rate. This is called traffic shaping.



45. What is multicast routing?

Sending a message to a group is called multicasting, and its routing algorithm is called multicast routing.



46. What is region?

When hierarchical routing is used, the routers are divided into what we will call regions, with each router knowing all the details about how to route packets to destinations within its own region, but knowing nothing about the internal structure of other regions.



47. What is silly window syndrome?

It is a problem that can ruin TCP performance. This problem occurs when data are passed to the sending TCP entity in large blocks, but an interactive application on the receiving side reads 1 byte at a time.



48. What are Digrams and Trigrams?

The most common two letter combinations are called as digrams. e.g. th, in, er, re and an. The most common three letter combinations are called as trigrams. e.g. the, ing, and, and ion.



49. Expand IDEA.

IDEA stands for International Data Encryption Algorithm.



50. What is wide-mouth frog?

Wide-mouth frog is the simplest known key distribution center (KDC) authentication protocol.



51. What is Mail Gateway?

It is a system that performs a protocol translation between different electronic mail delivery protocols.



52. What is IGP (Interior Gateway Protocol)?

It is any routing protocol used within an autonomous system.



53. What is EGP (Exterior Gateway Protocol)?

It is the protocol the routers in neighboring autonomous systems use to identify the set of networks that can be reached within or via each autonomous system.



54. What is autonomous system?

It is a collection of routers under the control of a single administrative authority and that uses a common Interior Gateway Protocol.



55. What is BGP (Border Gateway Protocol)?

It is a protocol used to advertise the set of networks that can be reached with in an autonomous system. BGP enables this information to be shared with the autonomous system. This is newer than EGP (Exterior Gateway Protocol).



56. What is Gateway-to-Gateway protocol?

It is a protocol formerly used to exchange routing information between Internet core routers.



57. What is NVT (Network Virtual Terminal)?

It is a set of rules defining a very simple virtual terminal interaction. The NVT is used in the start of a Telnet session.



58. What is a Multi-homed Host?

It is a host that has a multiple network interfaces and that requires multiple IP addresses is called as a Multi-homed Host.



59. What is Kerberos?

It is an authentication service developed at the Massachusetts Institute of Technology. Kerberos uses encryption to prevent intruders from discovering passwords and gaining unauthorized access to files.



60. What is OSPF?

It is an Internet routing protocol that scales well, can route traffic along multiple paths, and uses knowledge of an Internet's topology to make accurate routing decisions.



61. What is Proxy ARP?

It is using a router to answer ARP requests. This will be done when the originating host believes that a destination is local, when in fact is lies beyond router.





62. What is SLIP (Serial Line Interface Protocol)?

It is a very simple protocol used for transmission of IP datagrams across a serial line.



63. What is RIP (Routing Information Protocol)?

It is a simple protocol used to exchange information between the routers.



64. What is source route?

It is a sequence of IP addresses identifying the route a datagram must follow. A source route may optionally be included in an IP datagram header.

This Poster Published By
         S.G.Godwin Dinesh MCA