Running Doom on Our Custom CPU and Going Viral
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Hacker News
Engineers recently achieved a viral milestone by porting the 1993 classic game DOOM to a custom-built CPU. This project involved designing hardware at the logic gate level and deploying it on an FPGA to run the game in real time.
The Engineering Feat: Running DOOM on Custom Silicon
In a remarkable display of hardware engineering, a team of developers recently achieved the viral feat of running the 1993 seminal first-person shooter DOOM on a CPU designed entirely from scratch. While DOOM is famous for the community adage that it "can run on anything," moving from running the game on unconventional hardware like toasters or bacteria to creating a dedicated, custom-built processor represents a significant escalation in technical ambition.
Designing at the Logic Gate Level
The project’s complexity lies in the fundamental approach: the team did not simply repurpose existing architecture but instead designed a custom CPU at the logic gate level. This process requires an intimate understanding of instruction sets, data paths, and the physical constraints of digital logic. By building the processor from the ground up, the team had to ensure that their hardware could interpret and execute the complex instructions required to render the game's engine, which originally revolutionized 3D gaming through its use of ray-casting and sector-based geometry.
FPGA Deployment and Real-Time Execution
To bridge the gap between abstract design and physical reality, the team utilized a Field Programmable Gate Array (FPGA). This allowed them to synthesize their custom architecture into a functional device capable of running the game in real time. The transition from running simple, foundational programs to executing a resource-heavy software like DOOM is a testament to the robustness of their design, marking a successful validation of their custom instruction set architecture (ISA).
Adapting the Source Code
Beyond the hardware design, the project necessitated a deep dive into the DOOM source code. Because the engine was originally optimized for the hardware of the early 1990s, the developers had to adapt the codebase to communicate effectively with their specific custom peripherals and memory constraints. This bridge between legacy software and bespoke hardware highlights the enduring flexibility of the DOOM engine, which remains the gold standard for testing the capabilities of new or unusual computing platforms.
Broader Implications and Future Trends
This viral experiment serves as more than just a technical curiosity; it highlights a growing trend in the hobbyist and academic engineering communities toward open-source hardware and custom silicon design. As FPGAs become more accessible to enthusiasts, we are likely to see an increase in projects that push the boundaries of what is possible with custom microarchitecture. By successfully running a piece of gaming history on hardware they built themselves, these engineers have underscored the importance of understanding computing at its most fundamental, hardware-level abstraction.
Conclusion
The successful execution of DOOM on a custom CPU serves as a powerful case study in hardware-software integration. By successfully navigating the complexities of logic design, FPGA synthesis, and source code adaptation, the team has not only secured millions of views but has also demonstrated the profound technical prowess required to bridge the gap between modern computing needs and custom-built digital architecture.