Canon T4i DSLR Officially Unveiled, Features Touchscreen Display
Canon T4i DSLR
Classes of i.p
What is an i.p address???
An Internet Protocol address (IP address) is a numerical label assigned to each device (e.g.,computer, printer) participating in a computer network that uses the Internet protocol for communication. An IP address serves two principal functions: host or network interface identification and location addressing. Its role has been characterized as follows: "A name indicates what we seek. An address indicates where it is. A route indicates how to get there.Now i know many people didnt actually understand what the above definition actually means,just as i still dont understand why the definition is in such a complicated way.So i have my own version of defining an i.p,so here i go
"An i.p address is an address that identifies where the host(in short u) is located,using the
network id nd host-id that together form an i.p address."
To get into details of what a host id and network id is,nd how to identify which is host nd which
is network,let me giv u some examples and then explain them one by one.
A simple IP Address is a lot more than just a number. It
tells us the network that the workstation
is part of and the node ID. If you don't understand what I am talking about, don't let it worry you
too much because we are going to analyse everything here :)
IP Address Classes and Structure
When the IEEE committee sat down to sort out the range of
numbers that were going to be used by all computers, they came out with 5
different ranges or, as we call them, "Classes" of IP Addresses and
when someone applies for IP Addresses they are given a certain range within a
specific "Class" depending on the size of their network.
To keep things as simple as possible, let's
first have a look at the 5 different Classes:
In the above table, you can see the 5 Classes. Our first
Class is A and our last is E. The first 3 classes ( A, B and C) are used to
identify workstations, routers, switches and other devices whereas the last 2
Classes ( D and E) are reserved for special use.
As you would already know an IP Address consists of 32 Bits,
which means it's 4 bytes long. The first octec (first 8 Bits or first byte) of
an IP Address is enough for us to determine the Class to which it belongs. And,
depending on the Class to which the IP Address belongs, we can determine which
portion of the IP Address is the Network ID and which is the Node ID.
For example, if I told you that the first octec of an IP
Address is "168" then, using the above table, you would notice that
it falls within the 128-191 range, which makes it a Class B IP Address.
Understanding the Classes
We are now going to have a closer look at the 5 Classes. If
you remember earlier I mentioned that companies are assigned different IP
ranges within these classes, depending on the size of their network. For
instance, if a company required 1000 IP Addresses it would probably be assigned
a range that falls within a Class B network rather than a Class A or C.
The Class A IP Addresses were designed for large networks,
Class B for medium size networks and Class C for smaller networks.
Introducing Network ID and Node ID concepts
We need to understand the Network ID and Node ID concept
because it will help us to fully understand why Classes exist. Putting it as
simply as possible, an IP Address gives us 2 pieces of valuable information:
1) It tells us which network the device is part of (Network
ID).
2) It identifies that unique device within the network (Node
ID).
Think of the Network ID as the suburb you live in and the
Node ID your street in that suburb. You can tell exactly where someone is if
you have their suburb and street name. In the same way, the Network ID tells us
which network a particular computer belongs to and the Node ID identifies that
computer from all the rest that reside in the same network.
The picture below gives you a small example to help you understand
the concept:
In the above picture, you can see a small network. We have
assigned a Class C IP Range for this network. Remember that Class C IP
Addresses are for small networks. Looking now at Host A, you will see that its
IP Address is 192.168.0.2. The Network ID portion of this IP Address is in
blue, while the Host ID is in orange.
I suppose the next question someone would ask is: How do I
figure out which portion of the IP Address is the Network ID and which is the
Host ID ?
That's what we are going to answer next.
The Network and Node ID of each Class
The network Class helps us determine how the 4 byte, or 32
Bit, IP Address is divided between network and node portions.
The table below shows you (in binary) how the Network ID and
Node ID changes depending on the Class:
Explanation:
The table above might seem confusing at first but it's
actually very simple. We will take Class A as an example and analyse it so you
can understand exactly what is happening here:
Any Class A network has a total of 7 bits for the Network ID
(bit 8 is always set to 0) and 24 bits for the Host ID. Now all we need to do
is calculate how much 7 bits is:
2 to the power of 7 = 128 Networks and for the hosts : 2 to
the power of 24 = 16,777,216 hosts in each Network, of which 2 cannot be used
because one is the Network Address and the other is the Network Broadcast
address (see the table towards the end of this page). This is why when we
calculate the "valid" hosts in a network we always subtract "2".
So if I asked you how many "valid" hosts can you have a on Class A
Network, you should answer 16,777,214 and NOT 16,777,216.
Below you can see all this in one picture:
Class B networks have 14 bits for the Network ID (Bits 15,
16 are set and can't be changed) and 16 bits for the Host ID, that means you can
have up to '2 to the power of 14' = 16,384 Networks and '2 to the power of 16'
= 65,536 Hosts in each Network, of which 2 cannot be used because one is the
Network Address and the other is the Network Broadcast address (see the table
towards the end of this page). So if I asked you how many "valid"
hosts can you have a on Class B Network, you should answer 65,534 and NOT
65,536.
Class
C networks have 21 bits for the Network ID (Bits 22, 23, 24 are set and can't
be changed)
and 8 bits for the Host ID, that means you can have up to '2
to the power of 21' = 2,097,152 Networks and '2 to the power of 8' = 256 Hosts
in each Network, of which 2 cannot be used because one is the Network Address
and the other is the Network Broadcast address (see the table towards the end
of this page). So if I asked you how many "valid" hosts can you have
a on Class C Network, you should answer 254 and NOT 256.
Now, even though we have 3 Classes of IP Addresses that we
can use, there are some IP Addresses that have been reserved for special use.
This doesn't mean you can't assign them to a workstation but in the case that
you did, it would create serious problems within your network. For this reason
it's best that you avoid using these IP Addresses.
The following table shows the IP Addresses that you should
avoid using:
IP
Address
|
Function
|
Network
0.0.0.0
|
Refers to the default route. This
route is to simplify routing tables used by IP.
|
Network
127.0.0.0
|
Reserved
for Loopback. The Address 127.0.0.1 is often used to refer to the local host.
Using this Address, applications can address a local host as if it were a
remote host.
|
IP
Address with all host bits set to
"0" (network address) e.g
192.168.0.0
|
Refers to the actual network
itself. For example, network 192.168.0.0 (Class C) can be used to identify
network 192.168.0. This type of notation is often used within routing tables.
|
IP
Address with all node bits set
to "1" (Subnet/network broadcast)
e.g 192.168.255.255
|
IP
Addresses with all node bits set
to "1" are local network broadcast addresses and mustNOT be
used.
Some
examples: 125.255.255.255 (Class A) ,
190.30.255.255 (Class B), 203.31.218.255 (Class C).
|
IP
Address with all bits set to
"1" (Network Broadcast) e.g 255.255.255.255
|
The
IP Address with all bits set to "1" is a broadcast address and
must NOT be used. These are destined for all nodes on a
network, no matter what IP Address they might have.
|
Memory banking
Two-part Addresses and Memory Segmentation
Memory addressing is the centerpiece of the memory management function of an operating system. Early systems had flat memory models in which each byte was numbered sequentially from zero. The address of any byte in memory was in effect just the ordinal number telling "which" byte it was, e.g., the seven hundred twenty-third or the forty-three thousand two hundred ninth. Programmers referred to each byte by its sequence number in their programs. These numbers are called "absolute" or "physical" addresses. Computers later became more complicated (in order to get more powerful). One change was that within programs, programmers could refer to memory locations (particular bytes) by other numbering systems than the physical one, and the operating systems and/or CPUs would automatically translate from one to the other.
Vintage 1980 microcomputers used physical addressing, and confined themselves to using 4-digit hexa numbers as addresses. The highest you can count with a 4-digit hexadecimal number is FFFF in hex, equivalent to 65535 in decimal. So no more than 65536 bytes or 64K of memory could be used. Even if you could have installed more, the computer could not have used it for lack of ability to refer to it.
The IBM designers wanted to allow for 1MB of memory, or 16 times as much as the previous 64K limit. But because they had all registers only 16 bit that is 2 bytes they did not wish to use numbers wider than 16 bits in their addressing system. So a system of compound addresses. Each compound address contained 2 16-bit numbers. These were the first "segmented addresses" in microcomputers and the second one called as the offset address.
To understand this in a better way let me lead with an example in decimal. Forget hexadecimal, and computers, for a moment. In decimal we'll do the same thing that the 1981 PC architects did. Suppose till now we have been content to confine ourselves to counting using 2-digit numbers. Of course, that gave us the scope to count within the range from zero to ninety-nine. That has always been adequate. Ninety-nine is enough. It really has never occurred to us to count any higher.
Now however, an ambitious engineer wants to do just that. He knows he can do it if he allows a third digit. That gets us beyond the 99 barrier alright, not only to 100 but all the way up to the unimaginably huge number 999. For design reasons though, the engineer chooses to avoid using 3-digit numbers. Instead he opts to invent a system of compound numbers, consisting of 2 ordinary 2-digit number and a special way of interpreting them.
On the number line he will mark all numbers that are multiples of 10, starting with 0. Then he will use his first 2-digit number to identify a particular "deci-mark" on the number line. If his 2-digit number is 00 he's talking about the mark at 0. If it's 01, the mark at 10. If it's 02, the mark at 20,..., if it's 09, the mark at 90. If it's 10, the one at 100. If it's 11, the one at 110. If it's 25, he means the mark at 250. Since his 2-digit numbers go up to 99 before they run out of gas, he now has a technique of referring, as the limit of his reach, to the point at 990 on the number line. What he has sacrificed is the ability to refer to any of the "in-between" numbers, like 11 or 19 or 255. He has diluted his 2-digit number so it goes farther. He gained scope at the expense of precision. That's the purpose of the second 2-digit number: to supply restored precision.
Say he wants to refer to the number 763. He could select, as his first 2-digit number, 76. Because of the special, new "times ten" method of interpretation, we know this refers to the number 760. So he constructs a second 2-digit number to get him the rest of the way from 760 to 763. And that number is of course 3, which we'll write 03 to make it 2 digits. His notation system calls for him to write:
76:03
when he wishes to talk about 763. He now has a way to talk about it, but has successfully avoided using 3-digit numbers. Note he could land on 763 several other ways. For example, by starting at 750 instead of 760, then advancing 13 instead of 3. Just as the 43 yard line on the gridiron is equivalently a 3 yard gain from the 40, a 13 yard gain from the 30, or a 23 yard gain from the 10. All, same thing. So our engineer could write any of the following to refer to 763:
76:03
75:13
74:23
73:33
72:43
71:53
70:63
69:73
68:83
67:93
That's it. He can't let his first number go any lower than 67, because that would leave him short of 763 by more than 99, and the second number can only raise him 99 beyond his first one. You can make up the following rule for converting one of these compound addresses into a non-compound (i.e., regular 3-digit) one: to find the 3-digit linear address, take the left number of the compound address, shift it left one place (i.e., multiply it by 10), then add the right number.
The PC architects did pretty much the same thing. Instead of starting with 2-digit decimal numbers that provide a range of up-to-99, they started with 4-digit hex nos.providing a range of up-to-65536. But they compounded their numbers just the same way. And they ended up with an expanded reach. Their new reach, instead of extending up to 999 (just about a thousand), extended up to 1048575 ( just about a megabyte). But the system was the same. Consider an address 8F11:312A. The interpretation of this compound address and resulting absolute address is:
Note the above arithmetic is hexadecimal arithmetic, not decimal arithmetic. And note the result, 9223A, is much bigger than is FFFF, the previous counting ceiling. The two numbers have names. The left one is the segment address, and the right one is the offset address. Using this system to refer to memory locations is called memory segmentation. It's a way of making two 4-digit (hexadecimal) numbers do the work of one 5-digit number.
This was the new style of addressing by IBM's 1981 PC architects. Meanwhile, Intel's CPU designers made their own contribution. They came out with a chip (the 8086) that featured some new registers called segment registers. Programmers would work with the two-part addresses by doing two things within their programs. When they wanted to use a certain address, they would first take the segment address half of it and write it into the segment register. Thereafter, they would forget about the segment and write only the offset addresses within their code. They could get away with leaving out an explicit segment in all their address references due to the way the CPU worked. It was designed to blend (add) with the programmer's offset addresses whatever number was sitting in the segment register. And to do it every time there was an address reference, automatically. The segment address wasn't really omitted from the code, just implicit.
When you as a programmer put a number in a segment register you have in effect defined something called a "segment." This is a section of memory 64K bytes long. If the segment address is, for example, 2915, then the addresses in this segment start at 2915:0000 and go up to 2915:FFFF, which is the highest address in this particular segment. This range expressed in terms of absolute or physical addresses is from 29150 through 3914F. The relationship between a segment and the register which defines it is shown below.
Packet transfer
SAMSUNG I9300 IS 'NOT' THE SAMSUNG GALAXY S III
But not to worry the Samsung i9300 is a superb smart phone if the specs given here are true. It has a 4-inch 720p AMOLED display. This device has a dual-core 1.4Ghz processor and Mali 400MP GPU. This device comes with 1GB of RAM and runs on Android 4.0.3 Ice Cream Sandwich. From these specs we can clearly say that this brings somewhat more than the Galaxy S II.
How to take screenshots of iPhone
How do you grab a high quality screenshot image of the iPod Touch 2.0 or the iPhone 3G screen without downloading any screen capture app or using a digital camera?
To take a screenshot of any iPhone screen and save that a picture on your computer, upgrade your iPhone OS to firmware version 2.0 in case you are still using the old firmware. If you have an iPhone 3G, you already have a built-in screen capture function.
The hidden Print Screen in iPod Touch & iPhone:
In order to take a screen capture of the iPhone or iPod, press and hold the Home button that is located at the bottom center of the iPhone and is more often used to return to the default screen of your iPhone.
While your hold the home button, also press the Sleep / Wake key on top of iPhone and a screenshot of the existing screen will get saved to your iPhone or iPod photos folder. The iPod / iPhone screen will flash momentarily to indicate that a screenshot has been captured.
javascript exp-5
<html>
<head>
<script type="text/javascript">
function startTime()
{
var today=new Date();
var h=today.getHours();
var m=today.getMinutes();
var s=today.getSeconds();
// add a zero in front of numbers<10
m=checkTime(m);
s=checkTime(s);
document.getElementById('txt').innerHTML=h+":"+m+":"+s;
t=setTimeout('startTime()',500);
}
function checkTime(i)
{
if (i<10)
{
i="0" + i;
}
return i;
}
var c=0;
var t;
var timer_is_on=0;
function timedCount()
{
document.getElementById('txt').value=c;
c=c+1;
t=setTimeout("timedCount()",1000);
}
function doTimer()
{
if (!timer_is_on)
{
timer_is_on=1;
timedCount();
}
}
function stopCount()
{
clearTimeout(t);
timer_is_on=0;
}
function timeMsg()
{
var t=setTimeout("alertMsg()",3000);
}
function alertMsg()
{
alert("Hello");
}
var i=0;
for (i=0;i<=5;i++)
{
document.write("The number is " + i);
document.write("<br />");
}
var txt="";
function message()
{
try
{
adddlert("Welcome guest!");
}
catch(err)
{
txt="There was an error on this page.\n\n";
txt+="Click OK to continue viewing this page,\n";
txt+="or Cancel to return to the home page.\n\n";
if(!confirm(txt))
{
document.location.href="#";
}
}
}
function show_alert()
{
alert("I am an alert box!");
}
function show_confirm()
{
var r=confirm("Press a button");
if (r==true)
{
alert("You pressed OK!");
}
else
{
alert("You pressed Cancel!");
}
}
function show_prompt()
{
var name=prompt("Please enter your name","vivek nayyar");
if (name!=null && name!="")
{
document.write("<p>Hello " + name + "! How are you today?</p>");
}
}
var i;
var mycars = new Array();
mycars[0] = "Saab";
mycars[1] = "Volvo";
mycars[2] = "BMW";
for (i=0;i<mycars.length;i++)
{
document.write(mycars[i] + "<br />");
}
function myFunction()
{
var fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits.sort();
var x=document.getElementById("demo");
x.innerHTML=fruits;
}
</script>
</head>
<body onload="startTime()">
<div id="txt"></div>
<pre>
<form>
<input type="button" value="Start count!" onclick="doTimer()" />
<input type="text" id="txt" />
<input type="button" value="Stop count!" onclick="stopCount()" />
</form>
<form>
<input type="button" value="Display alert box in 3 seconds"
onclick="timeMsg()" />
</form>
<input type="button" value="View message" onclick="message()" />
<input type="button" onclick="show_alert()" value="Show alert box" />
<input type="button" onclick="show_confirm()" value="Show confirm box" />
<input type="button" onclick="show_prompt()" value="Show prompt box" />
</pre>
</body>
</html>
Motorola Xyboard 8.2 will zoom your view
Motorola Xyboard 8.2 Review:
Nick named as the successor of the Honeycomb tablet, Motorola xyboard 8.2 happened to be the talk of New Year. The phone got popularity specifically among the younger generation on behalf of its classy look which adds to the stylish trend of the youngsters. The size of the phone plays a vital role as it should not disturb the users which is very well understood by the Moto family and therefore designed the tab with most comfy structure and dimension of 8.2 inch for the external appearance to make its holding an extremely happier sensation to the hands. Yet another feather is being added by its nature of being slim and light weight that measures around 386 grams.
Hardware configuration:
The internal specification of the device can be best regarded by its dual-core 1.2 GHz processor with supplement of Ram of 1 GB capacity both of which stands as proof for speedy operation. For the external look, Motorola has flourished the edges of the covering with rubber attachments that are firmed with the phone through aid of six screws to bestow the grippe feel to the users. There is a 3.5mm head phone jack lies simply left to the IR blaster on center of the tab. On the other side, lolls one from a pair of speakers. The alternate one is being shifted to underside with the ports for micro-USB and micro-HDMI in conjunction with openings for LTE SIM. The LCD display covers 1280×800 area with inclusion of the 5MP camera with 1.3 Mp cameras on face for video calling. An indicator plunges your attention whenever you have text at the inbox for you, which is operated by the LED lights.
Software configuration:
The Android operating system that acts as base for this motorola xyboard 8.2 is declared to be latest edition that have touched the market in the March of 2011, Android 3.2 Honeycomb. The further newest arrival will win the position of Xyboard 8.2 only after the few periods in the fore coming months. The Motorola family has gifted the apps to users such as MotoCast that hands on for the free flowing of media and Quickoffice HD for aiding on creativity and like many more.
Battery Backup:
The battery life is portrayed to be at least for five hours and twenty five minutes only, which somewhat reduces the grace of the phone but the engagement with CDMA rises its hand as compared to others. But none can beat the place of the Xyboard 8.2 on one fact that its connection with the network seems pretty faster and download speed of which defeats other in the race. Nearly same results for the upload speed too.
Conclusion:
At last when comes to the conclusion, it is just stated that the comparison of the Xyboard 8.2 with the rest in market holds bit good result for it, simply due to its size that fits well on the palm and on superior performance. Further, an extraordinary wireless network provision suits to the person who goes on air for many times.
New Aspects Related to Android Application Development
Android application developement is one of the recent growing trends and its amazing immediate success has taken everyone by surprise. There is an increasing demand for the Android mobile devices as it includes fascinating features and price of these mobile devices, would definitely suit the budge of the people of all income groups.
This mobile opearting system is coupled with important mobile applications and middleware and has been developed on the Linux Kernel and API’s that have been penned down in the C programming language. Its functioning system can also be used on other types of devices, such as tablet computers, mobile phones, net books, smart phones and others. It actually functions on the foundation of the application framework that comprises libraries, which are completely compatible with Java and are strongly based on the Apache Harmony. It also includes in itself VGA, 3D graphics library, 2D graphics library and offers immense support to formats, such as audio media format and video media format. Android devices also offer support to network connection platforms, such as the IDEN, Bluetooth, GSM, Wi-Fi and EDGE.
The SQLite database is made use of for the purpose of restoration and storage of data. Since it does not make any type of distinction between the prime applications of this phone and the 3rd party applications, the possibility for development is broader.
This mobile device has to its credit 20,000 applications, thus it can claim to dominate the market of mobile applications and most of these applications can be downloaded for free by the users. According to recent estimation at least 30,000 of these mobile devices are activated on a regular day to day basis. The key basis for the success story of the Android applications is its innovative and superior benefits, which the buyers or rather the users of the smartphones can enjoy. The best feature of these devices is that it allows you to perform business tasks irrespective of location and time.
The functional operations offered by this application are playing of a music as per the choice of the user, opening of a phone contact in a easy and quick way, editing a note, to name only a few. Apart from these, this application offers numerous services,
For this reason, there is also a high demand for the developers of Android applications who are well versed with all the nuances related to it. The developers, to live up to the expectations of their organizations, need to employ new techniques and apply new and innovative ideas.
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