Just A Little Bit

That represents 24 bits—count them.  However, the only way the computer sees them  is as electrical conditions.

In the light switch analogy, the 0's and 1's would represent the off and on positions needed to form VIC in lights.

A lot of bits for just 3 letters you might be thinking.

But think about this—those 24 bits can be rearranged to form a multitude of different patterns.
It might not seem apparent, but in fact,  there are 16,777,216  unique possibilities with 24 bits!  If that were a lottery ticket, your odds of winning (getting the right combo of 24 digits) would be 1 in 16,777,216 (that's 16 MILLION....).

Obviously, the more bits you have the more  unique patterns you can form or  the more instructions the computer can process.

Let's start with a  single bit. One bit can't do very much.

As we already know, one bit can represent only  two values, 0  or  1

With two bits, it  would be like having two light switches on your wall. Two bits can have 4  different values.

The number of  possible unique  values DOUBLES with EACH bit you add. (2 to the power)
It's an amazing exponential growth as you will see.

Therefore, 3 bits = 8 values.  Now the possibilities are:

We call a collection of 8 bits a byte and it takes one byte to form one plain character(a number, letter or symbol).

If you count all the common  printable characters on your keyboard—26 lower case letters, 26 upper case letters, 10 numbers, and 32 punctuation keys—you come up with 94 keys. As you can see from the bit values in the sample list above, 7 bits can have 128 unique values. This is more than enough to display all those characters and others, and  in fact, 7 bits are enough to identify each character.

I.e., A= 1000001 (in your computer,  however,  A is stored as 01000001 since 8 bits per character is the standard—read on).

The binary values of all  those keyboard characters  have been standardized into what is known as the ASCII code (pronounced askey) which stands for American Standard Code for Information Exchange, and each character has been assigned a decimal value to make it easier for us to deal with the long binary values.

For example,  A = 65  B=66, C=67, D=68, and so on.  Try it—open a text document and press ALT + 65  on the number pad of your keyboard (make sure to have the num lock on). It should display the letter A. Of course, your computer only sees the binary value, regardless if you press A directly or Alt + 65. 

There are 128 characters( the complete number of possibilities for 7 bits)  in the Standard ASCII code (numbered 0 to 127). The first 32  codes represent non printable characters, many of which are obsolete and  no longer used. They date back to the days of teletype terminals.  ASCII was finalized in 1968, and in case you are not aware, ASCII means plain text. When you hear the term "ASCII" file, it just means a text file—plain and unformatted. ASCII is most commonly used for transmitting data— as when you send a plain text email—and was actually developed as a telecommunication standard.

Here's a chart  I made to show you the Standard (0 -127) ASCII character set,  with their binary, hex and decimal equivalents.

http://www.personal-computer-tutor.com/ascii.html

If you're observant, you will notice that the chart shows 8, not 7 bits for each character. The reason for this is that the ASCII code  was later updated to an extended 8 bit set which is enough for 256 characters. So a  0 value is usually added as the 8th bit.

For example, the character A in original ASCII is 1000001, but you'll usually see it listed as  01000001. And all the characters are stored in 8 bit (one byte) format in your computer.

You can see  that too—open up Notepad, type a single character and save. Then look at the File size in Properties.

That 0 bit also serves a function as an error checking or parity bit during transmissions.

Now a bit more about this Extended ASCII Set. As I said, it's an 8 bit code which is enough to encode 256, 8 bit characters—enough for the previous Standard 7 bit set with the extra 0 bit,  and the extended characters which consist of 128  special symbol characters that require the full 8 bits to identify. So in total, there are 256 characters in the ASCII code (0 to 255).

However, the  extended set is usually  shown separately. In other words we have the Standard set covering character numbers 0 to 127 and an Extended set which covers character numbers 128 to 255. Also, the extended ASCII code is not a true standard in the sense that different extended sets exist (using the same codes can give you different characters depending on your computer),  but the original was created for the IBM PC and that's the most commonly known set. Here are a few of them, most of which you can get in Windows by pressing Alt + the code or if that doesn't work, use the code at an MS-Dos prompt.

128 = Ç  129 = ü  130 = é  131 = â  132 = ä 133 = à  134 = å 135 = ç 136 = ê 137 = ë 138 = ê 139 = ï 140 = î 141 =ì 142 = Ä 143 = Å 144 = É  145 = æ 146 = Æ 147 = ô 148 = ö 149 = ò 150 = û  151 = ù  152 = ÿ 153 = Ö 154 = Ü 155 = ¢ 156 = £ 157 = ¥

To see the entire extended character set along with decimal, hex and binary equivalents, see my extended ASCII page here:
http://www.personal-computer-tutor.com/extended.htm

Hexadecimal Number System

Though the Decimal system is used for the ascii code, it is not the best number system to represent binary values in a computer. The hexadecimal system is much better and in fact, the most widely used number system to represent binary values. Hex values are used not only for characters, but for specifying colors, memory addresses, and in programming.  Also, If you play in the Windows registry at all, you are probably familiar with class id (clsid) keys that follow this alpha numeric format—{441E9D47-9F52-11D6-9672-0080C88B3613}—which are actually hex values. The source of program files are also commonly viewed with in hex format with hex editors.

Hex stands for 6 and decimal stands for 10. Hexadecimal counts 0 to 9, and then A B C D E F  Why hex you might be asking?  Because it's a compact and more  logical and compatible number system to use with binary. It's also easier to use than decimal for mental math (but you would have to become fluent in it as you are in decimal to know). Two hexadecimal digits neatly represent 8 bits:

As you've learned, the highest number of possibilities for 8 bits is 256 in DECIMAL  (0 to 255)
In hex, this would translate to 00 to FF.

But still, whether you use 0 to 255, or 00 to FF, to your computer it's only binary bits:  00000000 to 11111111.

All conversions are just man's attempt to make the binary system easier to work with.

As already mentioned,  the ASCII code only applies to plain unformatted text. It's what you use when you type a plain text email or inside a notepad document. The one byte per character does not apply to formatted characters  such as rich text or html with different font styles, colors and sizes.  Such characters would naturally  require more than 8 bits and much more than 256 possibilities to show all the variations possible with formatting. But, as we know, each single bit added DOUBLES the unique values possible.

By just adding one more byte, which is made up of  8 bits, the number of unique values jumps to  65,536!

That makes a character standard  like the 16 bit Unicode possible  which can encode over 65,000  different characters - enough to support almost every language.  What a difference a byte can make, eh?

So:

Even 64 bits doesn't sound like much—only 8 bytes—the ASCII equivalent of ABCDEFGH, but the possible unique values are mind boggling.

Because of this, computers are limited to the number of bits they can handle at one time - 64 bits is the max, currently.

In  binary that 64 bits making up the string ABCDEFGH translates to:

That shows the maximum number of bits that can be processed at one time to calculate 8,496,527,156,231,722 possible unique results.

And that's basically what is meant when you hear of computers being referred to as 16 bit, 32 bit or 64 bit. The number refers to how many bits the CPU can manipulate at one time or the amount of data it can process per clock cycle.

If in a 32 bit processor, more than 32 bits are needed for a job,  the computer needs to do more math work breaking down the numbers and recombining them.

For example, a 32 bit processor can add two 32 bit numbers at one time. For a 16 bit processor  to do the same would require two instructions instead of just one to come up with the same answer.

So that means the 32 bit processor can process double the amount of data than a 16 bit processor can, in the same time ( twice as fast). Likewise, a 64 bit processor has the potential to do the job twice as fast as a 32 bit one. The Apple Power Mac G-5 was the first widely available 64 bit system for consumers. However, the majority of  home PC's  today,  are 32 bit, though it shouldn't be long before 64 bit becomes common.

Image quality is also measured by bit—by bit depth—the number of bits used for one pixel.
The more bits per pixel, the higher the image quality.  To make this easy to understand, let's again begin with a single bit.

You now know that one bit can only be in one of two states. But it's important to realize that the computer doesn't care what you use to associate those off and on electrical states with. 0's and 1's.can  be Yes or No,  True or False,  Open or Close,  Black and White or whatever else. So with a one bit image, we can use Black or White,  Red or Blue, or any two colors, which means, all you can expect with a one bit image  is a monochrome  image—a single solid color.   But add 7 more bits, and you have an 8 bit image—and as you've seen in the ASCII section, 8 bits = 256 values. Again those values can be applied to anything logical. So with an 8 bit image, we have an image capable of displaying 256 different colors.

A 16 bit image can have  65,536 color variations.
A 24 bit image can have 16, 777,216 color variations (my name VIC, remember?)

Bit depth is also often specified with video cards, i.e., 32 bit graphics which equates to
4,294,967,296 values and more than enough for realistic 3D rendering.

More bits per anything always equals better quality or performance. Same applies to sound bits—when you hear of sound being referred to as 8 bit or 16 bit, it refers to the sampling size. With 8 bits you can have 256 levels but with 16 bits you can have 65,536 levels. 16 bits also gives you double the dynamic range of 8 bits. 16 bit is the CD standard.  Even higher quality is DVD audio which play 24 bit samples.

With sound cards, the bit specification does not refer to sample size.  For example, a 32 bit sound card does not mean 32 bit sound quality!

Your CD quality remains 16 bits.  32 bits refers more to the performance of the card—the  bit size of the data path—how many bits can travel  through at one time. For a 32 bit card it's 4,294,967,296 bits (again,  the maximum possibilities for 32 bits). For a 16 bit sound card, the path is 65,536 bits wide. In general, this means the 32 bit card will play your music and sounds more smoothly.

What about bits in relation to memory and hard drives?

In a nutshell,  bits—0's and 1's  can be recorded (tape drives make this obvious). With RAM, the recording is electrical and, as you know, when you turn off the power, the electricity is gone, and thus so is the data in the RAM chips. 

A hard drive on the other hand uses magnetism to permanently record 0's and 1's. So the data remains.

With memory and hard drives, we are dealing with holding and storage capacities only and we measure them in bytes.

Many hard drive makers misrepresent the capacity of their hard drives by using the decimal system to calculate size which means you can be losing out on several gigs when you buy a new hard drive. For more info on this, see my upcoming article in ABC, entitled "When a Byte Isn't a Byte" which also includes a byte converter I made.

This is the link but it's  not due for release till November 8.
http://personal-computer-tutor.com/abc3/v30/vic30.htm

Vic

Wintips&Tricks
http://groups.yahoo.com/group/WinTips-Tricks/

Powerpoint to EXE
http://www.angelfire.com/va3/vic3/index.html