Low level language

A low level programming language is a programming language where you have more direct control over the computer’s hardware. This means you can write code that interacts closely with the CPU, memory, and other hardware components.

Often, each instruction you write in a low level language corresponds closely to a single machine code instruction that the CPU can execute directly. This allows for really efficient and optimized code, but it also means that low level languages can be much harder to write programs in!

Examples of low level languages

There are only two low level languages:

Machine code - the binary instructions that the CPU executes directly.
Assembly language - a human-readable representation of machine code, using instructions (like MOV, ADD, SUB, etc) to represent the binary ‘opcodes’.

Uses of low level languages

Low level programming languages are used in:

Writing operating systems and system software
Writing device drivers
Embedded systems programming
Performance-critical applications (like game engines, graphics rendering, etc)
Reverse engineering and security research

That last one is because, often, a program is compiled down to machine code, so if you want to understand how it works, you need to read the low level code!

“Everything is open-source if you know assembly” ;)

Advantages of low-level languages

High performance (runs fast) IF you know what you’re doing
Complete control over hardware

Disadvantages of low-level languages

Hard to learn and use
Time-consuming to write and maintain
Not portable across different hardware architectures
- This one is key. If you write some assembly code for an x86 CPU, it won’t run on, say, an ARM or RISC-V CPU without being rewritten. This is unlike high level languages, which can often be compiled or interpreted on different architectures with little to no changes (thanks to the LLVM project).

flashcards

Question	Answer
What is a low level programming language?	A programming language that gives more direct control over a computer’s hardware, with instructions that often correspond closely to machine code instructions.
What are the only two examples of low level languages?	Machine code (binary instructions for the CPU) and assembly language (a human-readable representation using instructions like MOV, ADD, SUB).
List four common uses of low level programming languages.	Writing operating systems and system software, writing device drivers, embedded systems programming, performance-critical applications (like game engines), and reverse engineering/security research.
What is a major advantage of low level languages?	High performance (runs fast) if you know what you’re doing, and complete control over hardware.
What are three key disadvantages of low level languages?	Hard to learn and use, time-consuming to write and maintain, and not portable across different hardware architectures (e.g., x86 code won’t run on ARM).
Why is lack of portability a key disadvantage?	If you write assembly code for one architecture (e.g., x86), it cannot run on another (e.g., ARM or RISC-V) without being rewritten, unlike many high level languages which can be compiled/interpreted across architectures with little change.