ASCII Code
The abbreviation ASCII stands for American Standard Code for Information Interchange. It is a coding standard for characters, numbers, and symbols that is the same as the first 128 characters of the ASCII character set but differs from the remaining characters. These other characters are usually called special ASCII characters of Extended characters which have been defined by IBM.
The first 32 characters which are ASCII codes 0 through 1FH, form a special set of non-printing characters. These characters are called the control characters because these characters perform various printer and display control operations rather than displaying symbols. These characters have been listed in the ASCII character table given in this chapter. These control characters have following meanings:
NUL (Null):
No character. It is used for filling in time or filling space on the surface (such as surface of platter) of storage device where there are no data. We’ll use this character when we’ll be doing programming for data wipers (destructive and non-destructive both) to wipeout the unallocated space so that deleted data may not be recovered by any one or by any program.
SOH (Start Of Heading):
This character is used to indicate the start of heading, which may contain address or routing information.
STX (Start of Text):
This character is used to indicate the start of text and in this way this is also used to indicate the end of the heading.
ETX (End of Text):
This character is used to terminate the text that was started with STX.
EOT (End Of Transmission):
This character indicates the end of the transmission, which may have included one or more “tests” with their headings.
ENQ (Enquiry):
It is a request for a response from a remote station. It is a request for a station to identify itself.
|
