Tuesday, April 26, 2011
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?
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
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.