Table of Contents

NAME

ASCII - American Standard Code for Information Interchange

ASCII is a standard binary code used to represent character data on computers. Most existing computers, printers, terminals, etc. use the ASCII code to communicate with each other. Older IBM systems such as 360 family mainframes use another code called EBCDIC (Extended Binary Coded Decimal Interchange Code).

The standard ASCII code uses 7 bits to represent each character. This provides codes from 0000000 to 1111111 (0 to 127 decimal). Modern computers use an 8 bit ASCII character, although the latter codes, 10000000 to 11111111 (128 to 255 decimal) are not standardized.

Codes 00000000 to 00011111 (0 to 31 decimal) are the control characters. These characters has various effects on printers and terminals. For example, sending a line-feed (LF) character to a printer causes the paper to scroll. Sending the same character to an ASCII terminal will cause the cursor to move down, the analog to a paper scroll on a printer. If the cursor is already at the bottom of the screen, then the screen will scroll up. The following is a list of the control characters and their purpose:

Name    Decimal code    Function
NUL     0               No effect - marker or delay
SOH     1               Start of header
STX     2               Start of text
ETX     3               End of text flag
EOT     4               End of transmission flag
ENQ     5               Enquiry
ACK     6               Positive acknowledgement
BEL     7               Ring printer or terminal bell
BS      8               Backspace - move left
HT      9               Horizontal TAB - Move right to next tab stop
LF      10              Line feed
VT      11              Vertical TAB
FF      12              Form feed (new page)
CR      13              Carriage return - go to left margin
SO      14              Shift out
SI      15              Shift in
DLE     16              Data link escape
DC1     17              Device control 1
DC2     18              Device control 2
DC3     19              Device control 3
DC4     20              Device control 4
NAK     21              Negative acknowledgement
SYN     22              Syncronize
ETB     23              End of transmission block
CAN     24              Cancel
EM      25              End of medium
SUB     26              Substitute
ESC     27              Escape - start of special sequence
FS      28              Form separator
GS      29              Group separator
RS      30              Record separator
US      31              Unit separator

Codes 00100000 to 01111110 (32 to 126 decimal are the printable characters.

The printable characters are grouped in several sections.

Code 00100000 (32 decimal) is the space character.

Codes 00110000 to 00111001 (48 to 57 decimal) are the digit characters '0' to '9'. The character '0' has ASCII code 48 When you type '0' on your keyboard, the computer receives a binary 00110000 (48 decimal) from your terminal, not a binary 0.

Codes 01000001 to 01011011 (65 to 71 decimal) are the capital letters.

Codes 01100001 to 01111011 (97 to 123 decimal) are the lower case letters. Note that the code for a lower case letter differs by only 1 bit from the code for the same upper case letter. This feature is intended to make it easy to capitalize or decapitalize text.

Code 01111111 (127 decimal) is the delete character.

All remaining codes between the digits and letters are used for various punctuation symbols.

The following is a table of all 256 characters. The appearance of non-standard characters 128 to 255 (third and fourth columns) will depend on the type of terminal you are viewing this on. If your terminal supports an alternate character set, it will be shown following the standard character set.