A system programming language is a

programming language A programming language is a system of notation for writing computer programs. Most programming languages are text-based formal languages, but they may also be graphical. They are a kind of computer language. The description of a programming ...

used for

system programming Systems programming, or system programming, is the activity of programming computer system software. The primary distinguishing characteristic of systems programming when compared to application programming is that application programming aims to ...

; such languages are designed for writing

system software System software is software designed to provide a platform for other software. Examples of system software include operating systems (OS) like macOS, Linux, Android and Microsoft Windows, computational science software, game engines, search engin ...

, which usually requires different development approaches when compared with application software.

Edsger Dijkstra Edsger Wybe Dijkstra ( ; ; 11 May 1930 – 6 August 2002) was a Dutch computer scientist, programmer, software engineer, systems scientist, and science essayist. He received the 1972 Turing Award for fundamental contributions to developing progra ...

refers to these language as Machine Oriented High Order Languages, or mohol. Proceedings published 1974. General-purpose programming languages tend to focus on generic features to allow programs written in the language to use the same code on different platforms. Examples of such languages include

ALGOL ALGOL (; short for "Algorithmic Language") is a family of imperative computer programming languages originally developed in 1958. ALGOL heavily influenced many other languages and was the standard method for algorithm description used by the ...

and Pascal. This generic quality typically comes at the cost of denying direct access to the machine's internal workings, and this often has negative effects on performance. System languages, in contrast, are designed not for compatibility, but for performance and ease of access to the underlying hardware while still providing high-level programming concepts like

structured programming Structured programming is a programming paradigm aimed at improving the clarity, quality, and development time of a computer program by making extensive use of the structured control flow constructs of selection ( if/then/else) and repetition ( ...

. Examples include SPL and ESPOL, both of which are similar to

in syntax but tuned to their respective platforms. Others are cross-platform but designed to work close to the hardware, like

BLISS BLISS is a system programming language developed at Carnegie Mellon University (CMU) by W. A. Wulf, D. B. Russell, and A. N. Habermann around 1970. It was perhaps the best known system language until C debuted a few years later. Since then, C b ...

JOVIAL JOVIAL is a high-level programming language based on ALGOL 58, specialized for developing embedded systems (specialized computer systems designed to perform one or a few dedicated functions, usually embedded as part of a larger, more complete dev ...

and

BCPL BCPL ("Basic Combined Programming Language") is a procedural, imperative, and structured programming language. Originally intended for writing compilers for other languages, BCPL is no longer in common use. However, its influence is still ...

. Some languages straddle the system and application domains, bridging the gap between these uses. The canonical example is C, which is used widely for both system and application programming. Some modern languages also do this such as

Rust Rust is an iron oxide, a usually reddish-brown oxide formed by the reaction of iron and oxygen in the catalytic presence of water or air moisture. Rust consists of hydrous iron(III) oxides (Fe2O3·nH2O) and iron(III) oxide-hydroxide (FeO(OH) ...

and

Swift Swift or SWIFT most commonly refers to: * SWIFT, an international organization facilitating transactions between banks ** SWIFT code * Swift (programming language) * Swift (bird), a family of birds It may also refer to: Organizations * SWIFT, ...

Features

In contrast with application languages, system programming languages typically offer more-direct access to the physical hardware of the machine: an archetypical system programming language in this sense was

. System programming languages often lack built-in

input/output In computing, input/output (I/O, or informally io or IO) is the communication between an information processing system, such as a computer, and the outside world, possibly a human or another information processing system. Inputs are the signals ...

(I/O) facilities because a system-software project usually develops its own I/O mechanisms or builds on basic monitor I/O or screen management facilities. The distinction between languages used for system programming and application programming became blurred over time with the widespread popularity of

PL/I PL/I (Programming Language One, pronounced and sometimes written PL/1) is a procedural, imperative computer programming language developed and published by IBM. It is designed for scientific, engineering, business and system programming. I ...

, C and Pascal.

History

The earliest system software was written in

assembly language In computer programming, assembly language (or assembler language, or symbolic machine code), often referred to simply as Assembly and commonly abbreviated as ASM or asm, is any low-level programming language with a very strong correspondence b ...

primarily because there was no alternative, but also for reasons including efficiency of object code, compilation time, and ease of debugging. Application languages such as FORTRAN were used for system programming, although they usually still required some routines to be written in assembly language.

Mid-level languages

Mid-level languages "have much of the syntax and facilities of a higher level language, but also provide direct access in the language (as well as providing assembly language) to machine features." The earliest of these was ESPOL on Burroughs mainframes in about 1960, followed by

Niklaus Wirth Niklaus Emil Wirth (born 15 February 1934) is a Swiss computer scientist. He has designed several programming languages, including Pascal, and pioneered several classic topics in software engineering. In 1984, he won the Turing Award, generally ...

PL360 PL360 (or PL/360) is a system programming language designed by Niklaus Wirth and written by Wirth, Joseph W. Wells Jr., and Edwin Satterthwaite Jr. for the IBM System/360 computer at Stanford University. A description of PL360 was published in earl ...

(first written on a Burroughs system as a

cross compiler A cross compiler is a compiler capable of creating executable code for a platform other than the one on which the compiler is running. For example, a compiler that runs on a PC but generates code that runs on an Android smartphone is a cross ...

), which had the general syntax of

ALGOL 60 ALGOL 60 (short for ''Algorithmic Language 1960'') is a member of the ALGOL family of computer programming languages. It followed on from ALGOL 58 which had introduced code blocks and the begin and end pairs for delimiting them, representing a ...

but whose statements directly manipulated CPU registers and memory. Other languages in this category include

MOL-360 MOL-360 is a mid-level systems programming language for the IBM System/360 family of computers based on Algol. The only data structure supported by the language is arrays. It has no support for floating point data, but allows direct access to ...

and

PL/S PL/S, short for Programming Language/Systems, is a "machine-oriented" programming language based on PL/I. It was developed by IBM in the late 1960s, under the name Basic Systems Language (BSL), as a replacement for assembly language on internal ...

. As an example, a typical PL360 statement is R9 := R8 and R7 shll 8 or R6, signifying that registers 8 and 7 should be and'ed together, the result shifted left 8 bits, the result of that or'ed with the contents of register 6, and the final result placed into register 9.

Higher-level languages

While PL360 is at the semantic level of assembly language, another kind of system programming language operates at a higher semantic level, but has specific extensions designed to make the language suitable for system programming. An early example of this kind of language is LRLTRAN, which extended Fortran with features for character and bit manipulation, pointers, and directly addressed jump tables. Subsequently, languages such as C were developed, where the combination of features was sufficient to write system software, and a

compiler In computing, a compiler is a computer program that translates computer code written in one programming language (the ''source'' language) into another language (the ''target'' language). The name "compiler" is primarily used for programs th ...

could be developed that generated efficient object programs on modest hardware. Such a language generally omits features that cannot be implemented efficiently, and adds a small number of machine-dependent features needed to access specific hardware abilities;

inline assembly In computer programming, an inline assembler is a feature of some compilers that allows low-level code written in assembly language to be embedded within a program, among code that otherwise has been compiled from a higher-level language such as ...

code, such as C's statement, is often used for this purpose. Although many such languages were developed, C and

C++ C, or c, is the third letter in the Latin alphabet, used in the modern English alphabet, the alphabets of other western European languages and others worldwide. Its name in English is ''cee'' (pronounced ), plural ''cees''. History "C" ...

are the ones which survived.

System Programming Language A system programming language is a programming language used for system programming; such languages are designed for writing system software, which usually requires different development approaches when compared with application software. Edsger ...

(SPL) is also the name of a specific language on the

HP 3000 The HP 3000 series is a family of 16-bit and 32-bit minicomputers from Hewlett-Packard. It was designed to be the first minicomputer with full support for time-sharing in the hardware and the operating system, features that had mostly been limit ...

computer series, used for its operating system

HP Multi-Programming Executive MPE (Multi-Programming Executive) is a discontinued business-oriented mainframe computer real-time operating system made by Hewlett-Packard. While initially a mini-mainframe, the final high-end systems supported 12 CPUs and over 2000 simultaneous ...

(MPE), and other parts of its system software.

Major languages

Notes

References

External links

* {{cite journal , title=PL/I as a Tool for System Programming , journal=Datamation , date=1969-05-06 , first=Fernando , last=Corbató , pages=68–76 , url=http://home.roadrunner.com/~pflass/PLI/plisprg.html , access-date=2012-01-23
System Programming Languages
Programming language topics System software Systems programming languages