大学计算机基础大学计算机基础 (24).ppt

Characters in the digital worldEncoding English charactersThe encoding of English characters usually uses ASCII(American Standard Code for Information Interchange)code.There are two types of ASCII codes:7-bit version and 8-bit version.The 7-bit version is commonly used internationally.The 7-bit version has 128 elements,including 34 control characters,10 Arabic numerals,52 uppercase and lowercase English letters,32 various punctuation marks and arithmetic symbols.In the computer,8 characters are used to represent a character,and the highest bit is 0.The table lists the ASCII codes of all 128 symbols048A65a97Space32Expressed in hexadecimal,030HA41HEncoding Chinese characters All Chinese characters and symbols of the national standard form a 94 94 matrix.In this square matrix,each row is called a“zone”(zone code is 01-94),and each column is called a“bit”(bit number is 01-94),the square matrix actually constitutes a Chinese character set with 94 zones,and each zone has 94 bits.Each Chinese character or symbol has a unique position code in the code table,which is called the characters area code.Area code,GB code,Internal codeArea code(decimal)Area code(hexadecimal)2020HGB(National standard)codeArea code,GB code,Internal codeGB code(hexadecimal)+8080HInternal codeArea code,GB code,Internal codeIn the Chinese character matrix,the encoding of In the Chinese character matrix,the encoding of“中中中中”makes makes 54 rows and 48 54 rows and 48 columnscolumns01（54 48）D=（36 30）H Area code02（36 30）H+（20 20）H=（56 50）H GB code03（56 50）H+（80 80）H=（D6 D0）H Internal codeFont codeThe font code of a Chinese character is like the storage code of a black-and-white image(binary image),which only uses black and white colors.The font code of 24 24 dot matrix needs to be expressed by 72 bytes(24 24 8=72).