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A detailed reverse-engineering analysis of the microcode inside the Intel 8087 floating-point coprocessor, focusing on the FXCH register exchange instruction and the chip's internal architecture.
The article details z386, an open-source FPGA implementation of an 80386 CPU built using the original Intel microcode. It can boot DOS 6/7, run protected-mode programs, and play classic games like Doom, serving as both an educational reconstruction and a usable FPGA CPU.
A blog post detailing the successful disassembly and analysis of the Intel 80386 microcode, revealing 215 instruction entry points and the complex internal architecture.
A detailed blog series documenting the design and implementation of a scientific calculator from scratch using FPGA, covering numerical methods, CPU architecture, microcode, and hardware prototyping.
This project implements a fully functional scientific calculator in hardware using an FPGA, including a custom soft CPU, microcode firmware, and supporting tools. It provides a web-based simulator and open-source Verilog code.
A detailed reverse-engineering analysis of how the Intel 8087 floating-point coprocessor decodes instructions, explaining the interplay between the main CPU and coprocessor, the use of microcode ROM, and the bus interface unit.
A detailed technical analysis of the Intel 8086 processor's arithmetic-logic unit (ALU) control circuitry, explaining how microcode and control signals coordinate to perform 28 different operations.
A detailed examination of the conditional tests used in the Intel 8087 floating-point coprocessor's microcode, part of a reverse-engineering effort to understand its algorithms.
A detailed examination of the Pentium processor's microcode ROM, describing its structure, capacity, and how microcode implements machine instructions at the hardware level.