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Guy Harris (talk | contribs) Use the Wayback Machine for a now-dead link. |
Guy Harris (talk | contribs) Most of the references for the statement about non-portability are talking about assembly language as the only example of a low-level language; move that to the section about assembly language. |
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A '''low-level programming language''' is a [[programming language]] that provides little or no [[Abstraction (computer science)|abstraction]] from a computer's [[instruction set architecture]], memory or underlying physical hardware; commands or functions in the language are structurally similar to a processor's instructions. These languages provide the programmer with full control over program memory and the underlying machine code instructions. Because of the low level of abstraction (hence the term "low-level") between the language and machine language, low-level languages are sometimes described as being "close to the hardware".
== Machine code ==
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== Assembly language ==
An [[assembly language]], classified as a [[second-generation programming language]],<ref name=":3"/><ref name=":4"/> provides a level of abstraction on top of machine code. A program written in assembly language is [[Software portability |non-portable]], due to being written and optimized for a particular architecture.<ref name=":0">{{Cite web |date=2021-03-05 |title=3.1: Structure of low-level programs |url=https://workforce.libretexts.org/Bookshelves/Information_Technology/Information_Technology_Hardware/Advanced_Computer_Organization_Architecture_(Njoroge)/03%3A_Computer_Organization_and_low-level_Programming/3.01%3A_Structure_of_low-level_programs |access-date=2023-04-03 |website=Workforce LibreTexts |language=en}}</ref><ref>{{Cite web |date=2023-11-19 |title=What is a Low Level Language? |url=https://www.geeksforgeeks.org/what-is-a-low-level-language/ |access-date=2024-04-27 |website=GeeksforGeeks |language=en-US}}</ref><ref>{{Cite web |title=Low Level Language? What You Need to Know {{!}} Lenovo US |url=https://www.lenovo.com/us/en/glossary/low-level-language/ |access-date=2024-04-27 |website=www.lenovo.com |language=en |url-status=dead |archive-url=https://web.archive.org/web/20240724093734/https://www.lenovo.com/us/en/glossary/low-level-language/ |archive-date=2024-07-24}}</ref><ref>{{Cite web |title=Low-level languages - Classifying programming languages and translators - AQA - GCSE Computer Science Revision - AQA |url=https://www.bbc.co.uk/bitesize/guides/z4cck2p/revision/2 |access-date=2024-04-27 |website=BBC Bitesize |language=en-GB}}</ref>
An [[assembly language]], classified as a [[second-generation programming language]],<ref name=":3"/><ref name=":4"/> provides a level of abstraction on top of machine code. In the early days of coding on computers like [[TX-0]] and [[PDP-1]], the first thing [[MIT]] [[Hacker culture|hackers]] did was to write assemblers.<ref name=":1">{{cite book|last=Levy|first=Stephen|year=1994|title=Hackers: Heroes of the Computer Revolution|title-link=Hackers: Heroes of the Computer Revolution|publisher=Penguin Books|page=32|isbn=0-14-100051-1}}</ref>▼
Assembly language has little [[Semantics (computer science)|semantics]] or formal specification, being only a mapping of human-readable symbols, including symbolic addresses, to [[opcode]]s, [[memory address|addresses]], numeric constants, [[string (computer science)|strings]] and so on. Typically, one [[machine instruction (computing)|machine instruction]] is represented as one line of assembly code, commonly called a ''mnemonic''.<ref>{{Cite web |title=Machine Language/Assembly Language/High Level Language |url=https://www.cs.mtsu.edu/~xyang/2170/computerLanguages.html |access-date=2024-04-27 |website=www.cs.mtsu.edu |archive-url=https://web.archive.org/web/20241214053921/https://www.cs.mtsu.edu/~xyang/2170/computerLanguages.html |archive-date=2024-12-14 |url-status=dead}}</ref> Assemblers produce [[object file]]s that can [[linker (computing)|link]] with other object files or be [[loader (computing)|loaded]] on their own. Most assemblers provide [[macro (computer science)|macros]] to generate common sequences of instructions.
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== C programming language ==
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