Alphanumeric code - AbsoluteAstronomy.com

SYNOP

SYNOP is a numerical code used for reporting weather observations made by manned and automated weather stations. SYNOP reports are typically sent every six hours on shortwave using RTTY...

and CLIMAT

CLIMAT

CLIMAT is a code for reporting monthly climatological data assembled at land-based meteorological surface observation sites to data centres. CLIMAT-coded messages contain information on several meteorological variables that are important to monitor characteristics, changes, and variability of climate...

(alphanumeric codes used for meteorological and climatological data transmission)

In general, in computing

Computing

Computing is usually defined as the activity of using and improving computer hardware and software. It is the computer-specific part of information technology...

, an alphanumeric code is a series of letters and numbers (hence the name) which are written in a form that can be processed by a computer.

Specifically, in computer hacker

Hacker (computer security)

In computer security and everyday language, a hacker is someone who breaks into computers and computer networks. Hackers may be motivated by a multitude of reasons, including profit, protest, or because of the challenge...

terminology, alphanumeric code

Code

A code is a rule for converting a piece of information into another form or representation , not necessarily of the same type....

is machine code

Machine code

Machine code or machine language is a system of impartible instructions executed directly by a computer's central processing unit. Each instruction performs a very specific task, typically either an operation on a unit of data Machine code or machine language is a system of impartible instructions...

that is written so that it assembles into entirely alphanumeric ASCII

ASCII

The American Standard Code for Information Interchange is a character-encoding scheme based on the ordering of the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that use text...

or Unicode

Unicode

Unicode is a computing industry standard for the consistent encoding, representation and handling of text expressed in most of the world's writing systems...

characters such as 0-9, A-Z and a-z. This type of encoding was created by hackers

Hacker (computer security)

to hide working machine code inside what appears to be text. This can be useful to avoid detection of the code and to allow the code to pass through filters that modify or remove non-alphanumeric characters unchanged. A similar type of encoding is called printable code and uses all printable

Control character

In computing and telecommunication, a control character or non-printing character is a code point in a character set, that does not in itself represent a written symbol.It is in-band signaling in the context of character encoding....

characters (0-9, A-Z, a-z, !@#%^&* etc...) It has been shown that it is possible to create shellcode that looks like normal text in English.

Writing alphanumeric or printable code require good understanding of the instruction set architecture of the machine on which the code is to be executed.

See also

Further reading