<P> Assembly language uses a mnemonic to represent each low - level machine instruction or opcode , typically also each architectural register , flag , etc . Many operations require one or more operands in order to form a complete instruction and most assemblers can take expressions of numbers and named constants as well as registers and labels as operands , freeing the programmer from tedious repetitive calculations . Depending on the architecture , these elements may also be combined for specific instructions or addressing modes using offsets or other data as well as fixed addresses . Many assemblers offer additional mechanisms to facilitate program development , to control the assembly process , and to aid debugging . </P>
<P> Assembly language uses a mnemonic to represent each low - level machine instruction or opcode , typically also each architectural register , flag , etc . Many operations require one or more operands in order to form a complete instruction and most assemblers can take expressions of numbers and named constants as well as registers and labels as operands , freeing the programmer from tedious repetitive calculations . Depending on the architecture , these elements may also be combined for specific instructions or addressing modes using offsets or other data as well as fixed addresses . Many assemblers offer additional mechanisms to facilitate program development , to control the assembly process , and to aid debugging . </P>
a command that is recognized and executed by the assembler while the source code is being assembled
a command that is recognized and executed by the assembler while the source code is being assembled
machine instruction or opcode
machine instruction or opcode