Binary coding schemes

   Now let us consider an important question.  How are characters represented as 0s and 1s ("off" and "on " electrical states)  in the computer? The answer is the use of binary coding schemes.  A binary coding scheme assigns a unique sequence of bits to each character.  Two of the most popular binary coding schemes use eight bits or one byte.  There two codes are ASCII and EBCDIC.  A recently developed code,  Unicode use 16 bits.

• ASCII,  pronounced "as-key ", stands for American Standard Code for Information Interchange.  This is an alder code that is still widely used for microcomputer.  For example,  the number 3 is represented in ASCII code as 0011 0011.
• EBCDIC, pronounced "ed-see-dick", stand for Extended Binary coded Decimal Interchange Code.  It is an older code originally developed by IVM and used primarily for large computers.  For example,  the number 3 is represented in EBCDIC code as 1111 0011 
• Unicode is a family of 16-bit codes that support both ASCII and EBCDIC.  It is also used for international languages likes Chinese and Japanese.  There language have too many characters to be represented by the eight -bit ASCII and EBCDIC codes

      When you press a on the keyboard,  a character is automatically converted into a series of electronic pules that the system can recognize.  For example,  pressing the number 3 on a keyboard causes an electronic signal to be send to the microcomputer's system unit where it is converted to the character code of 0011 0011
        Coding schemes are particularly important to hardware designers and computer programmers for tracking down error and other of problems.  But why are coding schemes important to end users?  There are several reasons.  One of the most important is that data created by one computer system using a different coding schemes. Generally this is not a problem if both computers store data using this code.  However, problems can occur when data is shared between microcomputers mad older computers that use EBCDIC code.  The data may have to be translated from one coding scheme to the other before processing can begin.  Fortunately,  special conversion programs are available to help with this translation.