Assemblernotation

Assembler notation refers to the human‑readable format that assemblers use to translate assembly language code into machine code. The notation specifies the syntax for mnemonics, operands, labels, directives, and comments. It serves as the bridge between programmer intent and the binary instructions that the processor actually executes.

Two principal syntaxes dominate assembler notation: Intel and AT&T. Intel syntax places the destination operand first and the source operand second, uses register names without a prefix, and writes immediate constants without a leading symbol. For example: mov eax, 5. AT&T syntax reverses operand order, prefixes registers with % and immediates with $, and appends a suffix to indicate operand size, such as movl $5, %eax. These differences affect how programmers write and read code, but the underlying instruction(s) produced by the assembler are equivalent.

Beyond mnemonics and operand conventions, assembler notation includes directives that control data placement, program segments, and linkage. Directives such as .data, .text, .bss, .global, and .align partition memory and define symbol visibility. Byte‐oriented data can be inserted with .byte or .word, and strings with .asciz or .ascii. Comments are introduced by a semicolon or a hash symbol, depending on the assembler.

Assemblers such as MASM, NASM, TASM, and GNU Assembler (GAS) interpret these notations to generate object files. Their naming conventions for registers, flags, or instruction suffixes may differ, yet all adhere to the same intent: a clear, concise textual representation of processor operations that can be readily assembled into executable code.