Coding Schemes
Coding schemes are a common way of representing alphabetic, numeric, and special characters in the internal storage of computers or on magnetic media. They are necessary to exchange data in the computer. Any form of text-based data is stored in the form of bits or a series of 1s and 0s by a computer. This is done according to a specified encoding scheme, which is a standard that can tell the user which character represents which set of bytes.
There are many different coding schemes, but some of the most common include:
ASCII (American Standard Code for Information Interchange):
It is a character encoding scheme that uses 7 bits to represent each character. This means that there are a total of 128 possible characters that can be encoded in ASCII.
ASCII was developed in the 1960s, when computers had limited memory and storage capacity. 7 bits was enough to encode the characters that were needed at the time, including the numbers 0-9, the uppercase and lowercase letters of the Latin alphabet, and some punctuation marks.
ASCII works by assigning a unique 7-bit value to each character. For example, the character A is assigned the value 01000001, and the character B is assigned the value 01000010. These values can then be stored in computer memory or on magnetic media.
When a computer needs to display a character, it takes the 7-bit value of the character and converts it into a graphical representation. This is done by using a lookup table that maps the 7-bit values to the corresponding graphical representations.
ASCII is a simple and efficient encoding scheme, but it has some limitations. For example, it cannot represent all of the characters used in the world's languages. This is why other encoding schemes, such as Unicode, have been developed.
Here is a table that shows the ASCII values for some of the most common characters:
EBCDIC (Extended Binary Coded Decimal Interchange Code):
It is an 8-bit character encoding scheme that was developed by IBM in the 1960s. It is used by some mainframe computers and some other devices.
The reason why EBCDIC is an 8-bit encoding scheme is because it was designed to be more flexible than ASCII. ASCII uses 7 bits to represent each character, which means that it can only represent a total of 128 characters. EBCDIC uses 8 bits, which means that it can represent a total of 256 characters. This makes it possible for EBCDIC to represent a wider range of characters, including characters from non-Latin alphabets, as well as control characters that are not used in ASCII.
EBCDIC works by assigning a unique 8-bit value to each character. For example, the character A is assigned the value 11000001, and the character B is assigned the value 11000010. These values can then be stored in computer memory or on magnetic media.
When a computer needs to display a character, it takes the 8-bit value of the character and converts it into a graphical representation. This is done by using a lookup table that maps the 8-bit values to the corresponding graphical representations.
EBCDIC is a more complex encoding scheme than ASCII, but it offers some advantages. For example, it can represent a wider range of characters, and it is more efficient for storing data. However, ASCII is more widely used, and it is easier to learn.
Here is a table that shows the EBCDIC values for some of the most common characters:
Unicode:
Unicode is a 16-bit character encoding scheme that can represent a much wider range of characters than ASCII or EBCDIC. It is the most widely used encoding scheme today.
ASCII and EBCDIC are both 8-bit encoding schemes, which means that they can only represent a total of 256 characters. This is not enough to represent all of the characters used in the world's languages. Unicode, on the other hand, can represent a total of 1,114,112 characters. This makes it possible for Unicode to represent the characters used in almost all of the world's languages, as well as mathematical symbols, technical symbols, and emojis.
Unicode works by assigning a unique 16-bit code point to each character. A code point is a number that uniquely identifies a character. For example, the code point for the character A is 0x0041, and the code point for the character B is 0x0042. These code points can then be stored in computer memory or on magnetic media.
When a computer needs to display a character, it takes the code point of the character and converts it into a graphical representation. This is done by using a lookup table that maps the code points to the corresponding graphical representations.
Unicode is a more complex encoding scheme than ASCII or EBCDIC, but it offers a number of advantages. For example, it can represent a wider range of characters, and it is more future-proof. As new languages and symbols are developed, Unicode can be extended to accommodate them.
Here are some of the reasons why Unicode is the most widely used encoding scheme today:
- It can represent a wider range of characters than ASCII or EBCDIC.
- It is more future-proof.
- It is supported by a wide range of software and hardware.
- It is easy to learn and use.
Unicode is also a more efficient encoding scheme than ASCII or EBCDIC. This is because it uses fewer bits to represent each character. This makes it possible to store more data in a smaller amount of space.
Each coding scheme has its own advantages and disadvantages. For example, ASCII is simple and efficient, but it cannot represent all of the characters used in the world's languages. EBCDIC is more complex than ASCII, but it can represent a wider range of characters. Unicode is the most complex of the three encoding schemes, but it can represent the characters used in almost all of the world's languages.
The choice of which encoding scheme to use depends on the specific needs of the application. For example, if an application only needs to support English, then ASCII may be a good choice. However, if an application needs to support a wider range of languages, then Unicode may be a better choice.