Question

What is the output of an assembler?

Short answer

The output of an assembler is machine code.

Step-by-step solution

Understanding Assemblers

An assembler is a program that translates assembly language, which is a low-level language closely related to machine code, into machine code. Before understanding the output, it's important to know that assemblers perform this translation process to convert the human-readable instructions into a format that the computer can execute.

Defining Machine Code

Machine code is a set of instructions executed directly by a computer's CPU. It consists of binary or hexadecimal codes that represent machine operations in the computer's instruction set. As such, it is the most fundamental level of code to run on a computer.

Assembler Output

The output of an assembler is a machine code program, also known as an object file or an object code. This file contains the translated machine code instructions that correspond to the original assembly language instructions inputted by the programmer.

Determinants of the Output

The specific output can vary slightly based on settings such as the target architecture (like ARM, x86), the specific assembler used, and additional options during the assembly process, like linking symbols. However, the core output remains machine code ready for execution or further linking.

Key concepts

Machine Code

Machine code is the foundation upon which all software operates. It is a set of binary instructions that a computer's CPU understands directly. Assembly language is translated into machine code, which consists of patterns like 0s and 1s. These patterns instruct the CPU on operations to perform, such as moving data or executing calculations. Machine code is hardware-specific and operates at the lowest level of the computer's architecture. Because it communicates directly with the hardware, it is essential for executing any program on a computer.

Assembly Language

Assembly language bridges the gap between human-readable code and machine-level instructions. It is a low-level language that closely corresponds with a computer's instruction set. Unlike machine code, it uses mnemonic codes or symbols instead of binary.

• Easy to Understand: While still complex, it's more comprehensible than machine code.
• Hardware Specific: Directly correlates with the processor's instruction set.
• Translational Role: Requires an assembler to convert into machine code.

Assembly language provides programmers with more intuitive commands to work with, while still maintaining closeness to the hardware.

Object File

An object file is the end product of the assembly process. When an assembler translates assembly language into machine code, the result is an object file, a key part of the executable program.

• Contains: Machine code instructions ready for execution.
• State of Completion: Often a segment that requires linking to become a complete executable.
• Utilization: Typically combined with other object files or libraries.

The object file acts as a crucial intermediary, containing code that is yet to be fully assembled into a runnable application.

Instruction Set

An instruction set is a collection of commands that a processor can carry out. It defines how a CPU interprets and performs tasks included in a machine code.

• Specific to Architecture: Different processors have different instruction sets.
• Basic Commands: Includes simple arithmetic, control, and data handling instructions.
• Complexity Controls: Can define the efficiency and complexity of software at the machine level.

The instruction set is essential because it dictates the specific language the CPU speaks, influencing both the assembly language and the machine code that will run on it.