Reverse-engineering the Intel 8087: A look at microcode and register exchange
By
pwg
If you only eat one bagel today, this is the bagel.
Summary
A detailed technical deep-dive into the Intel 8087 floating-point co-processor's microcode, specifically examining the register exchange operation. The article explains how the 8087 used microcode to implement complex floating-point algorithms, and is part of a reverse-engineering project by the Opcode Collective to understand and document the chip's internal workings.
Key quotes
· 5 pulledIn 1980, Intel introduced the 8087 floating-point chip, a co-processor that made floating-point operations up to 100 times faster.
This chip was highly influential, and today most processors use the floating-point standard introduced by the 8087.
The 8087 uses complicated algorithms to accurately compute functions such as square roots, tangents, and exponentials.
These algorithms are implemented inside the chip in low-level code called microcode.
I'm part of a group, the Opcode Collective, that is reverse-engineering this microcode.
You might also wanna read
Disassembling the 80386 Microcode: A Deep Dive into Intel's Processor Architecture
A technical blog post detailing the author's process of disassembling and analyzing the microcode ROM of the Intel 80386 microprocessor. The
Zero-Copy GPU Inference from WebAssembly on Apple Silicon: Direct Memory Sharing Between Wasm and GPU
The article describes a technical breakthrough on Apple Silicon where WebAssembly modules can share linear memory directly with the GPU, ena
abacusnoir.com·1mo ago
Understanding CPU Pipelining and Its Evolution into Branch Prediction
This article explores CPU pipelining concepts as part of a branch prediction series, explaining how modern processors optimize instruction e
Tailslayer: C++ Library for Reducing RAM Tail Latency from DRAM Refresh Stalls
Tailslayer is a C++ library designed to reduce tail latency in RAM reads caused by DRAM refresh stalls. It works by replicating data across
github.com·1mo ago
Understanding CPU Branch Prediction and Its Impact on Benchmarking
The article discusses how modern processors use branch prediction to execute multiple instructions per cycle, explaining that CPUs have rema
lemire.me·2mo ago
nCPU: AI-Native Computing Platform with Neural Network-Based Architecture
nCPU is an AI-native computing platform where every layer from arithmetic to operating system to compiler is either a trained neural network
github.com·2mo ago