Unusual circuits in the Intel 386's standard cell logic

434 · Ken Shirriff · Nov. 22, 2025, 4:40 p.m.
Summary
This post explores unusual circuits in the Intel 386 processor, particularly its use of standard cell logic, which streamlined the chip's design process. It discusses various unique features of the 386's circuitry, such as large multiplexers and unexpected circuit configurations, drawing insights from reverse engineering. The author highlights the historical significance of these design choices in the context of the chip's successful development. Detailed illustrations and schematics are provided to support the analysis, suggesting that the post is capable of encouraging a deeper understanding of processor architecture.