## Machine Code - Machine language instructions - Directly control [CPU](Processors.md) - Strictly numerical - Lowest-level representation of a compiled or assembled program - Lowest-level visible to programmer - Internally microcode might used - Hardware dependent - Higher-level languages translated to machine code - [Compilers](Compilers.md), assemblers and linkers - Not for interpreted code - Interpreter runs machine code - [Assembly](Languages/Assembly.md) is effectively human readable machine code - Has mnemonics for opcodes etc ## Microcode - Layer between CPU hardware and instruction set architecture - Normally written during design phase - Deployed to ROM or PLA - Programmable logic array - Machine code often has some backward compatibility - Microcode is circuit specific ## Byte Code Portable Code - Efficient execution by interpreter - Compact numeric codes, constants and references - Encode compiler output following analysis and validation - Can be further compiled - [Compilers](Compilers.md#JIT) - Typically passed to VM - Java, [Python](Languages/Python.md) ## Object Code - Product of compiler - Sequence of statements - Machine code - Intermediate - RTL - Linked to form executable - Object code portion of machine code not yet linked