Ascii is of two types ascii 7 and ascii 8 ascii 7 is

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: al American computer manufacturers as their computers' internal code. This code is popular in data communications, is used almost exclusively to represent data internally in microcomputers, and is frequently found in the larger computers produced by some vendors. ASCII is of two types - ASCII-7 and ASCII-8. ASCII-7 is a 7-bit code that allows 128 (27) different characters. The first 3 bits are used as zone bits and the last 4 bits indicate the digit. Microcomputers using 8-bit byte (group of 8 bits for 1 byte) use the 7-bit ASCII by leaving the leftmost first bit of each byte as a zero. Figure 4.6 shows the alphabetic and numeric characters in ASCII-7 notation. ASCII-8 is an extended version of ASCII-7. It is an 8-bit code that allows 256 (2 8) different characters rather than 128. The additional bit is added to the zone bits. Figure 4.7 shows the alphabetic and numeric characters in ASCII-8 notation. Observe that other than the zone-value differences, ASCII-7 and ASCII-8 are identical. ASCII also uses hexadecimal as its four-to-one shortcut notation for memory dump. Figures 4.6 and 4.7 also show the hexadecimal equivalent of the ASCII notations. Example 4.7. Write the binary coding for the word BOY in ASCII-7. How many bytes are required for this representation? Character ASCII-7Code 0 1 .2 3 4 5 6 7* 8 9 Zone Oil Oil Oil Oil on on on on on on Hexadecimal Equivalent Digit 0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 30 31 32 33 34 35 36 37 38 39 A B C D E F G H I J K L M N 0 100 100 100 100 100 100 100 foo 100 100 100 100 100 100 100 0001 0010 0011 0100 0101 0110 0111 1000 1001 1010 1011 1100 1101 1110 mi 41 42 43 44 45 46 47 48 49 4A 4B 4C 4D 4E 4F P Q R S T U V W X Y Z 0 1 2 3 4 5 6 7 8 9 101 101 101 101 101 101 101 101 101 101 101 0101 0101 0101 0101 0101 0101 0101 0101 0101 0000 0001 - 0010 0011 0100 0101 0110 0111 1000 1001 1010 0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 50 51 52 53 54 55 56 57 58 59 5A 50 51 52 53 54 55 56 57 58 59 A B C D E F G 1010 1010 1010 1010 1010 1010 1010 0001 0010 0011 0100 0101 0110 0111 Al A2 A3 A4 A5 A6 A7 H I J K L M N O 1010 1010 1010 1010 1010 1010 1010...
View Full Document

Ask a homework question - tutors are online