Programming Languages: High-Level vs Low-Level

This lesson covers the difference between high-level and low-level programming languages, including machine code and assembly language. This is part of OCR J277 Section 1.5.3.

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What Is a Programming Language?

A programming language is a formal language used to write instructions that a computer can execute. These instructions tell the computer what operations to perform.

Programming languages can be divided into two broad categories:

1. High-level languages — closer to human language
2. Low-level languages — closer to machine language (binary)

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Low-Level Languages

Low-level languages are closer to the binary instructions that the CPU directly understands. There are two types:

1. Machine Code

Machine code is the lowest-level programming language. It consists entirely of binary (1s and 0s) and is the only language the CPU can directly execute.

Example (simplified):

10110000 01100001

Feature	Detail
Format	Pure binary (or sometimes hexadecimal)
Readability	Virtually impossible for humans to read
Portability	Not portable — specific to a particular CPU architecture
Speed	Fastest execution — no translation needed
Use	Rarely written directly; usually generated by translators

2. Assembly Language

Assembly language is a low-level language that uses mnemonics (short abbreviations) to represent machine code instructions. It is much easier to read than machine code but still very close to the hardware.

Example:

MOV AL, 61h    ; Move the hexadecimal value 61 into register AL
ADD AL, 05h    ; Add 5 to the value in register AL
HLT            ; Halt the processor

Feature	Detail
Format	Mnemonics (e.g. MOV, ADD, SUB, JMP, HLT)
Readability	Difficult but more readable than machine code
Portability	Not portable — specific to a CPU architecture
Translation	Requires an assembler to convert to machine code
Use	Device drivers, embedded systems, performance-critical code

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High-Level Languages

High-level languages use syntax that is closer to human language and mathematical notation. They are designed to be easier to read, write, and maintain.

Examples of High-Level Languages

Language	Common Use
Python	Education, data science, web development, scripting
Java	Enterprise applications, Android apps
C#	Windows applications, game development (Unity)
JavaScript	Web development (front-end and back-end)
C++	Games, operating systems, performance-critical applications