SYMPL: The Obsolete Programming Language of the 1970s and 1980s
In the history of computer programming, many languages have emerged and evolved over time, each serving specific needs of their era. Some languages, however, have become obsolete or are no longer in common use, yet they played crucial roles in the early development of computing. One such language is SYMPL, a programming language developed by the Control Data Corporation (CDC) in the 1970s for use on their CDC 6000 series computer systems. Though SYMPL is largely forgotten today, it was a significant player in the computing landscape of its time, offering a robust alternative to assembly language and other contemporary languages like Fortran.
Historical Context and Development of SYMPL
The 1970s were a pivotal decade for computing. Computer hardware was becoming more advanced, with larger memory capacities and faster processors. The CDC 6000 series, which was a major series of supercomputers produced by Control Data Corporation, was at the forefront of this technological revolution. These machines were used for scientific, engineering, and military purposes, and they required programming languages that could efficiently exploit their advanced capabilities.
SYMPL was developed as an alternative to assembly language and was specifically designed for the CDC 6000 series computers. Its primary purpose was to provide a higher-level programming environment that could allow for more structured, readable code while still maintaining the performance necessary for these high-powered systems. The language was based on a subset of JOVIAL, another programming language used by the military and other high-performance sectors. While JOVIAL was well-suited to certain tasks, SYMPL simplified its structure to make it more accessible for a broader range of programming applications.
Features of SYMPL
SYMPL, short for “Simplified Programming Language,” was a compiled, imperative, and procedural language. It incorporated several key features that made it distinct from both assembly language and other high-level languages of the time.
Strong Typing and Variable Declaration
One of the key features of SYMPL was its strong typing system. Unlike assembly language, where variables could be used without explicit declaration, SYMPL required that all variables be declared before they could be used in a program. This helped prevent many common programming errors and allowed the compiler to perform more rigorous checks during the compilation process.
The need to declare variables prior to use also meant that SYMPL supported more sophisticated data structures. Programmers could define complex data structures, including dynamically allocated “based” structures, which were crucial for managing memory efficiently in the context of the large, high-performance systems like the CDC 6000.
Data Structures and Memory Management
Compared to its contemporaries, SYMPL offered more advanced support for data structures. The language provided mechanisms for dynamic memory allocation, allowing developers to manage memory more efficiently than with languages like Fortran, which at the time relied on fixed memory allocations. This was particularly important for the CDC 6000, which was capable of running large and complex scientific applications that required sophisticated memory handling.
Structured Programming Constructs
SYMPL was designed with structured programming in mind, which was becoming a popular paradigm in the 1970s as developers sought to improve the reliability and maintainability of software systems. Structured programming emphasized the use of control structures such as loops, conditionals, and subroutines to promote clearer and more logical program flow.
In SYMPL, programmers could nest procedures and create more organized and modular code, which helped reduce errors and improve readability. The language provided built-in constructs that made it easier to structure programs without having to resort to the less manageable “goto” statements common in earlier languages.
In-Fix “Bead” and Character Manipulation
SYMPL also supported more advanced operations for manipulating data at a low level. This included the use of in-fix “bead” operations, which allowed for bit-level manipulation of data, a feature that was particularly useful for scientific and engineering applications requiring precise control over data. In addition, SYMPL supported character manipulation, a useful feature for text processing tasks that were becoming more common in software applications.
Macro Facility
Another notable feature of SYMPL was its simple macro facility. Macros allow programmers to define shorthand notations for frequently used code patterns, thus reducing the amount of repetitive typing required. This feature was an early precursor to the more sophisticated preprocessor directives found in later languages like C. While the macro facility in SYMPL was relatively basic, it nevertheless represented a useful tool for developers working on large projects.
Simplifications Compared to JOVIAL
While SYMPL shared its roots with JOVIAL, it was a simplified version of the latter language. One of the main differences was that SYMPL had fewer built-in data types, making it more streamlined and easier to use. Additionally, SYMPL did not support recursive procedure calls, a feature present in JOVIAL. This simplification helped avoid some of the complexities that came with recursion, making SYMPL more straightforward to learn and use, especially for those coming from a background in assembly language programming.
Another simplification in SYMPL was the absence of the COMPOOL concept, which was a memory-sharing mechanism used in JOVIAL. While this concept had its advantages in certain types of applications, its removal in SYMPL made the language easier to work with for simpler tasks.
Major Contributions and Implementations
During its short period of use, SYMPL played an important role in the development of software for the CDC 6000 series. A number of important CDC software products were implemented in SYMPL, including compilers, libraries, a full-screen editor, and major subsystems. These products demonstrated the power of the language and its ability to streamline software development on the CDC 6000 machines.
One of the most significant contributions was the implementation of a compiler for SYMPL itself. This allowed the language to be used to develop new programs and applications, creating a feedback loop that helped to refine the language and expand its capabilities. In addition, SYMPL was used to develop large-scale systems and tools that supported the military, scientific, and engineering applications for which the CDC 6000 was so well known.
Decline and Obsolescence
Despite its usefulness during the 1970s and early 1980s, SYMPL eventually fell out of favor as newer, more powerful programming languages gained traction. The rise of languages like C, Ada, and others that offered more advanced features, better portability, and greater community support made SYMPL less relevant. As the CDC 6000 series computers were phased out in favor of more modern systems, the need for SYMPL diminished, and the language was largely forgotten.
The obsolescence of SYMPL can be seen as part of a broader trend in the history of computing, where languages that were once groundbreaking eventually give way to more powerful and versatile alternatives. While SYMPL may not have had the lasting impact of languages like Fortran or C, it nonetheless played an important role in the evolution of programming languages during the early days of high-performance computing.
Conclusion
SYMPL was a significant programming language for its time, designed to meet the specific needs of the CDC 6000 series computers. It offered a high-level alternative to assembly language, with advanced features such as strong typing, dynamic data structures, structured programming, and low-level memory management. While it was ultimately overshadowed by more modern languages, SYMPL’s contributions to the development of computing in the 1970s and 1980s are undeniable. Its emphasis on structured programming, strong typing, and efficient memory handling laid the foundation for many of the programming concepts that would later become central to modern software development.
Though SYMPL is no longer in use today, its legacy lives on in the languages and systems that followed. For those with an interest in the history of programming languages, SYMPL serves as an important reminder of the early efforts to make computing more accessible and efficient, even as new languages and paradigms continue to evolve.