Designing a central processing unit (CPU) from scratch is a challenging task that requires the right tools, knowledge, and determination. However, when it comes to designing a graphics processing unit (GPU), the complexity increases significantly. A software engineer named Adam Majmudar embarked on the journey of creating a GPU from scratch and documented his struggles on Twitter. While the fundamentals of CPU and GPU architecture share some common aspects, GPUs have unique characteristics in terms of memory usage and thread management.
Majmudar’s experience in designing both a CPU and a GPU revealed the significant differences between the two. While a CPU primarily focuses on executing instructions and performing general computing tasks, a GPU is designed to handle parallel processing and offload tasks related to graphics and other complex calculations. The structure of a shader unit in a GPU resembles an arithmetic logic unit in a CPU, but the way they utilize memory and manage threads is distinct.
Creating a GPU from scratch is not just about designing a system for graphics processing; in Majmudar’s case, he aimed to develop a general-purpose GPU (GPGPU) for mathematical computations. This required solving a myriad of issues, from understanding how to optimize memory usage to managing parallel threads efficiently. Despite the similarities between CPUs and GPUs, the unique characteristics of GPU design presented new challenges that Majmudar had to overcome with the help of others.
After numerous iterations and adjustments, Majmudar was able to successfully run a basic GPU design that could perform matrix calculations in a software simulation. His CPU and GPU designs will be further developed through the Tiny Tapeout project, which aims to bring his creations into physical form. One of the remarkable aspects of Majmudar’s work is his decision to share the entire project on Github, providing a valuable resource for those interested in understanding GPU hardware at a deeper level.
While designing a GPU from scratch may seem like a daunting task, learning how to program a GPU is much more accessible. With an abundance of online resources, tutorials, and exercises available, anyone can acquire the skills needed to program a GPU effectively. However, delving into the intricacies of designing a shader unit at a transistor level, as Majmudar did, requires a deeper understanding of hardware architecture that is not readily available from major chip manufacturers like AMD, Intel, and Nvidia.
The process of designing a GPU from scratch is a complex and challenging endeavor that requires a combination of technical knowledge, problem-solving skills, and perseverance. While GPUs and CPUs share common aspects, the unique characteristics of GPU design present distinct challenges that must be addressed. Adam Majmudar’s journey in creating a GPU from scratch highlights the difficulties and rewards of pushing the boundaries of hardware design. By sharing his project openly, he has created a valuable resource for those seeking to explore the inner workings of GPU hardware.
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