While most individuals associate speedrunning strictly with video games, the concept has recently found its way into the realm of computer hardware design. Traditionally, speedruns involve completing a game or a specific level in the shortest time possible, pushing the boundaries of gameplay strategies. However, a unique intersection of speedrunning with CPU construction was recently showcased by Hackaday writer Julian Scheffers. His project, named Stovepipe, stands as a pioneering example of how the principles of efficiency and minimalism can be applied to the intricate field of computer architecture.
Scheffers undertook the ambitious task of designing and simulating a fully functional CPU from scratch within the remarkably short time frame of just six hours. The name “Stovepipe” was chosen somewhat whimsically as a placeholder rather than as a reference to sartorial history. The project’s primary focus was on streamlining the design process. In less than four hours, Scheffers effectively constructed the hardware, reserving the subsequent two hours for developing an assembler.
One of the most interesting aspects of Stovepipe is its instruction set architecture (ISA), which emerged through a minimalist lens. Unlike Scheffers’s earlier project, the GR8CPU, which boasted an impressive 8,192 bits, Stovepipe operates on a much leaner 512 bits. The reduction is the result of stripping away superfluous elements, leaving behind eight primary opcodes to handle essential computational tasks. This intense focus on simplicity not only serves the project’s ethos but also raises questions about what constitutes the ‘essence’ of a CPU from a design standpoint.
In its final form, Stovepipe represents a quintessential minimalist approach to CPU design. With a mere 256 bytes of RAM and no input/output ports, the design is remarkably sparse. The CPU utilizes an accumulator as its sole user-accessible register, emphasizing a streamlined operational model. Instruction execution is designed to be efficient, with fetching an instruction taking only one cycle, while running it requires between one to three cycles.
Despite its limitations, Stovepipe stands in stark contrast to its predecessor, Boa³², which featured a richer architecture with 32 registers and a more sophisticated pipelined design. While Boa³² executes instructions faster, the sheer rapidity with which Stovepipe was conceived is noteworthy. The speed at which these minimal architecture designs can emerge is a testament to the ingenuity involved in both the theory and practice of computing.
When comparing Stovepipe to previous builds, particularly Boa³² and the earlier GR8CPU, one can draw fascinating insights into the evolution of CPU design. Boa³², which took two months to complete, stands as a more powerful entity thanks to its pipelined architecture and dedicated data handling mechanisms. Conversely, Stovepipe, with its minimalist design, opens up a dialogue about efficiency versus power. Although it may not possess the raw speed of its predecessors, the speed of its creation signifies a revolutionary shift in how we perceive CPU design.
Scheffers mentioned the possibility of a sequel, Stovepipe 2, that would be timed with a speedrun timer—an intriguing proposition that reflects both the playful spirit of the project and the dedication to further refining the process. The potential development of a faster iteration of Stovepipe invites speculation on the future of CPU design, particularly when minimalism and time constraints are at play.
While the practical applications of rapidly designed CPUs such as Stovepipe may be limited, the achievement itself is groundbreaking. It challenges conventional wisdom about the timeline necessary for hardware design and stimulates a conversation around minimalist engineering. Scheffers’s work symbolizes a fantastic confluence of creativity, efficiency, and speed—elements that will likely inspire further exploration in both the gaming and computing realms. The merging of speedrunning concepts with hardware development stands not just as a novelty but as a new paradigm in CPU design that encourages a reevaluation of what is possible within the constraining frameworks of traditional engineering practices.