<P> Assembly language, or just assembly, is a low - level programming language, which uses mnemonics, instructions and operands to represent machine code . This enhances the readability while still giving precise control over the machine instructions . Most programming is currently done using high - level programming languages, which are typically easier to read and write . These languages need to be compiled (translated into assembly language), or run through other compiled programs . </P> <P> Opcodes can also be found in so - called byte codes and other representations intended for a software interpreter rather than a hardware device . These software - based instruction sets often employ slightly higher - level data types and operations than most hardware counterparts, but are nevertheless constructed along similar lines . Examples include the byte code found in Java class files which are then interpreted by the Java Virtual Machine (JVM), the byte code used in GNU Emacs for compiled LISP code, . NET Common Intermediate Language (CIL), and many others . </P>

The op code in a machine language instruction specifies the data