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[[Category:Computer Architecture]][[Category:Assembly Language]]''Assembly language'' is a [[Symbol|symbolic]] representation of [[Machine Language|machine language]]. It is therefore [[Portable|architecture-specific]].

Each instruction is represented by a short mnemonic word such as "LDR" for ''Load Register'', "MOV" for ''move'', or "MUL" for ''multiply'', followed by (optional) arguments. The [[Addressing Mode|addressing mode]] is implied by the format of the arguments. Different [[Assembler|assemblers]] use slightly different syntax.

Here is a "Hello, World!" program in x86 assembler for a Linux system, using the [http://www.nasm.us/xdoc/2.11/html/nasmdoc1.html#section-1.1 Nasm ] syntax:

Here is the same program with [https://sourceware.org/binutils/docs/as/ GNU Assembler (gas/as) ] syntax:

This is written in [https://sourceware.org/binutils/docs/as/ GNU Assembler (gas/as) ] syntax:

mov %r0, $1 /* file descriptor: 1 is stdout */ ldr %r1, =msg /* message location (memory address) */ ldr %r2, =len /* message length (bytes) */ mov %r7, $4 /* write is syscall #4 */ swi $0 /* invoke syscall */

mov %r0, $0 /* exit status: 0 (good) */ mov %r7, $1 /* kernel syscall number: 1 is sys_exit */ swi $0 /* invoke syscall */

.ascii "Hello, world!\n" len = . - msg

=== External Examples =Resources ==

"Hello World" in many different types of assembler: * [[Assembler Basics]]* [http://leto.net/code/asm/hw_assembler.php"Hello World" in many different types of assembler]* [[x86_64 Register and Instruction Quick Start]]* [[aarch64 Register and Instruction Quick Start]]