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Tuesday, April 19, 2011

Wednesday, April 13, 2011

Thursday, March 31, 2011

Conversions

Decimal

We count in what is called the decimal counting system. Decimal has 10 digits which are 0,1,2,3,4,5,6,7,8,9. Decimal is also called base 10 because it has 10 digits. The reason why people started counting in decimal is because it has 10 digits and we have 10 fingers and people used to use their fingers for counting.

Binary

Binary uses only 2 digits which are 0 and 1 and is also called base 2. Binary is what computers use for counting because inside a computer you get things that are like little switches that can be either off or on(0 or 1). A subscripted 2 is placed after a binary number so that it can be recognised as being a binary number like in the following example:

10012

We already know that when we count we add 1 to the current number each time to get the next number. If we start at 0 and then add 1 we get 1. Now we have to add 1 to 1 but we have run out of digits because there are only 2 digits in binary. When we get to 9 in decimal and add 1 we first change the number to a 0 and then add 1 to the imaginary 0 to the left of it which gives us 10. If we apply this to binary then we change the 1 to 0 and then increase the imaginary 0 to the left of it which gives us 10 but this 10 is actually 2. The following sequence shows you how to count to 5 in binary:

0 1 10 11 100 101

Hexadecimal

The word hexadecimal is made up of 2 parts which are hex(6) and decimal(10). If you add 6 and 10 together you get 16 and that is how many digits there are in hexadecimal. Hexadecimal is sometimes called hex or base 16. To get 16 digits we have to use letters of the alphabet and those 16 digits are 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F. Hexadecimal is often used instead of binary numbers because just 2 hexadecimal digits can make the same numbers as 8 binary digits which in turn make up a byte. A subscripted 16 is used to show that a number is hexadecimal:

7F16

Octal

Octal uses 8 digits which are 0,1,2,3,4,5,6,7 and is also called base 8. We use a subscripted 8 to show that a number is octal:

2758

Converting from decimal to binary, hexadecimal and octal

decimal -> binary2

5 -> binary2

First write a few 2s(because it's base 2) to the power of the numbers 0,1,2,3,...

23 22 21 20

Next calculate the values of these numbers.

8 4 2 1

The highest number must be greater than the number you want to convert.

Now divide the number to be converted by the number starting on the left. Write how many times the number divides into it underneath the number and then write your remainder on top of the next number to be divided. You then divide by the remainder each time after that.

5 5 1 1
8 4 2 1
0 1 0 1

The bottom line of numbers is the binary number. Make sure to leave out all leading 0s

5 -> 1012

decimal -> hexadecimal16

Decimal to hexadecimal works in the same way except that you use 16 to the power of those numbers since that is the base this time.

26 -> hexadecimal16

162 161 160

26 26 10
256 16 1
0 1 10

Before we write the answer we must change all numbers greater than 9 to their hexadecimal equivalents.

1 10
1 A

26 -> 1A16

decimal -> octal8

This time we use 8 to the power of those numbers because we are working with base 8.

12 -> octal8

82 81 80

12 12 4
64 8 1
0 1 4

12 -> 148

Converting from binary, hexadecimal and octal to decimal

binary2 -> decimal

11012 -> decimal

First write 2 to the power of the numbers 0,1,2,3,...

23 22 21 20

Now change them to their real values.

8 4 2 1

Now put the binary number underneath the other numbers and multiply the top number by the number beneath it and put the answer underneath the other 2 with + between each number and add the bottom row together to get your final answer.

8 4 2 1
1 1 0 1
8+4+0+1 = 13

11012 -> 13

hexadecimal16 -> decimal

Once again you use 16 instead of 2.

1F16 -> decimal

161 160

16 1
1 F
16+F = 16 + 15 = 31

1F16 -> 31

octal8 -> decimal

258 -> decimal

81 80

8 1
2 5
16+5 = 21

158 -> 21

Converting from hexadecimal to binary

hexadecimal16 -> binary2

2C16 -> binary2

First write the number as decimals.

2 12

Now divide each number by the numbers 8 4 2 1.

2 12
8421 8421
0010 1100

Take the leading 0s away and you have your answer.

2C16 -> 1011002

binary2 -> hexadecimal16

101112 -> hexadecimal16

First separate the binary number into groups of 4 digits. If the number at the front has less than 4 digits then add 0s to the front of it.

0001 0111

Now use the numbers 8421 and multiply each time and add the results together for each group to get the answer.

0001 0111
8421 8421
0+0+0+1 = 1; 0+4+2+1 = 7

101112 -> 1716

Converting from octal to binary

Octal to binary uses the same method as hexadecimal to binary except that you use the numbers 421 and groups of 3 digits.

octal8 -> binary2

268 -> binary2

2 6
421 421
010 110

268 -> 101102

binary2 -> octal8

10102 -> octal8

001 010
421 421
0+0+1 = 1; 0+2+0 = 2

10102 -> 128

Converting from hexadecimal to octal

We do not convert directly from hexadecimal to octal but instead first convert to binary and then to octal.

hexadecimal16 -> octal8

4516 -> octal8

First convert the hexadecimal number to binary.

4 5
8421 8421
0100 0101

Now make groups of 3 digits and then convert to octal.

001 000 101
421 421 421
0+0+1 = 1; 0+0+0 = 0; 4+0+1 = 5

4516 -> 1058

octal8 -> hexadecimal16

278 -> hexadecimal16

First convert the octal number to binary.

2 7
421 421
010 111

Make groups of 4 and then convert to hexadecimal.

0001 0111
8421 8421
0+0+0+1 = 1; 0+4+2+1 = 7

278 -> 1716

Friday, February 25, 2011

Google Music Streaming : Launching Soon?

Tonight (February 24th) is the night of the Google Android Honeycomb event, where we will get our first truly back to front view of the new OS. There are plenty of exciting features to talk about here, but one of the items that might be revealed is the Google Music Library. According to Android Community, who cites unnamed insider sources, tonight will be the night that the library is opened for business.

What exactly is the Google Music Library? There are at least three major facets. First, we have the actual music player itself. We know for a fact that this is coming out, since early debugging versions have been discovered and even released to the public for the Android 2.3 smartphone line. It may be that Honeycomb has a different interface, but in either case, the new browser is packed with features.

Second, we have the “OTA download library.” Discussed at last year’s Google I/O conference, the concept here is that you can purchase a song from a large, cloud-based music storehouse. That song can then be transferred to your phone over the air, pushed to your PC library, and otherwise attached to your Google account. This is, according to AC’s unnamed sources, going to be released alongside a revamped web-based Android marketplace.

And third, we have the “full library streaming” feature. This feature would allow users to connect their phone or tablet to their computer, streaming any song that’s currently located in their computer’s music library. This, more than the other features, is in question, partially due to simply logistics and partially due to the complex legal boundaries of allowing live music streams.

We’ll find out for sure in the next 24 hours, so stay tuned for further updates. Whatever the details, there’s little doubt that Google will make quite a showing during their official Honeycomb press event.

3 Free VPN Services Without Any Installation

To access those blocked websites, you can use free online proxy tools, free desktop proxy softwares, or below 3 free VPN (Virtual Private Network) services.

These three VPN services are all FREE and you can use them directly without installing anything in your computer.

1. MacroVPN

After registration, you will have 4 VPN server addresses, one from Italy, and the other three from USA, choose one and create a new VPN connection, then you can get access to the MacroVPN free VPN service with your username and password.

If the domain addresses (such as us6.macrovpn.com) are not workable, you can try to the IP addresses (such as 74.86.150.154) as server name, and if one VPN server is not workable, you can try another one.

The MacroVPN website supports English, Spanish, Chinese and many other languages.

Go to MacroVPN
2. ItsHidden

After registration, you can create a new Virtual Private Network connection with the VPN server address vpn.itshidden.com in your computer, and then you can get access to the ItsHidden VPN service with your username and password, but you need to reconnect every 20 minutes as a free user.

If the network access is not workable, you can try to change the VPN server address from vpn.itshidden.com to 94.75.253.244.

Go to ItsHidden
3. USA IP

For free user, you don’t need to register, just download the USAIP.pbk file, and then double-click on the file and select one of the USAIP PPTP connections. After that, you can get access to the USA IP free VPN services with the username demo and the password demo.

But you will need to reconnect the USA IP network after every 7 minutes.

Go to USA IP

All the above 3 free VPN services are tested and workable here in China, if you have any problem to use them, please let me know by adding a comment below.

[Update] It seems that ItsHidden does not offer free VPN any more.
 
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