One kilobyte Tiny BASIC for the 8080
In celebration of the Intel 8080’s birthday, a programmer has embarked on a fascinating project to develop a BASIC interpreter in assembly language that can fit into a mere 1K of memory. The result is an impressive accomplishment, as this interpreter not only boasts an array of features but also optimizes memory usage for program storage. While there are other sub-1K BASIC interpreters available, this particular one stands out for its richness in features and efficient memory utilization. The program’s performance is enhanced due to tokenization of programs. Though similar to Palo Alto Tiny BASIC in terms of features, it does have some syntax differences. Notably, it supports GOSUB/RETURN, FOR/NEXT loops, and functions such as RND, ABS, and USR. Additionally, it introduces a single array variable, @. Remarkably, this implementation is approximately 60% smaller than the smallest PATB (Palo Alto Tiny BASIC) implementation. The interpreter is written in 8080 assembly language and was developed using a bespoke 8080 emulator. While it has not been tested on a physical 8080 system, the developer eagerly awaits the opportunity to witness it in action for anyone who may have such a system available.
This achievement showcases the ingenuity and craftsmanship of the programmer, who managed to squeeze a fully functional BASIC interpreter into just 1K of memory. The project not only pays tribute to the Intel 8080 but also pushes the boundaries of what can be achieved in the realm of assembly language programming.
When asked about their motivation behind this endeavor, the programmer stated, I wanted to investigate writing a BASIC interpreter in assembly language and decided to fit a BASIC interpreter into 1K. This desire to explore and overcome the challenge of working within such tight constraints drove the development of this impressive interpreter.
In terms of functionality, this interpreter stands as one of the most feature-rich sub-1K BASIC interpreters available. By tokenizing the programs, it ensures efficient execution and processing speed. The support for GOSUB/RETURN, FOR/NEXT loops, and functions like RND, ABS, and USR enhances its capabilities, making it a powerful tool for budding programmers.
Despite its compact size, this interpreter manages to provide a satisfactory programming experience. With a single array variable (@), users can store and manipulate data efficiently. Furthermore, its size advantage, being only 60% of the smallest PATB implementation, allows for more flexibility and creative possibilities within the 1K memory footprint.
The interpreter’s development exercise took place using a custom 8080 emulator, perfectly tailored to facilitate seamless testing and debugging before deploying it on a physical 8080 system. The programmer, eager to witness their creation running on a genuine 8080, expressed interest in connecting with anyone who has access to such a system.
This remarkable achievement in the realm of assembly language programming not only showcases the possibilities within tight memory constraints but also highlights the dedication and creativity of programmers in pushing technological boundaries. While the interpreter is not yet battle-tested on a real Intel 8080 system, its potential and promise are evident, opening doors for further exploration and innovation in the world of microprocessors.
