Instruction decoding in the Intel 8087 floating-point chip
Summary
This article provides a deep dive into how the Intel 8087 coprocessor decodes instructions, including the ESCAPE mechanism, ModR/M usage, PLA-based instruction decoding, microcode control, and hardwired BIU paths. It uses diagrams and historical context to illustrate the complexity and engineering trade-offs behind instruction decoding in a vintage floating-point unit.