The article describes reproducing the GPT-2 (124M) model in llm.c, a C/CUDA implementation, in 90 minutes for $20 on a single 8X A100 80GB SXM node. The model is trained on 10 billion tokens of FineWeb data and achieves comparable performance to the original GPT-2 model. The article provides a step-by-step guide on how to reproduce the result on a Linux system with a GPU. The training process and results are also visualized using a Jupyter notebook.