8087 Assembly Examples for MS-DOS

This repository provides a curated set of example programs demonstrating how to use the Intel 8087 math coprocessor in conjunction with 8086/8088 assembly code under a real-mode MS-DOS environment.

📌 Purpose

The goal of this project is to serve as a practical reference for:

• Understanding how to perform floating-point arithmetic using the 8087
• Learning how the x87 FPU integrates with 8086/8088 instructions
• Demonstrating the use of FPU instructions such as FLD, FST, FADD, F2XM1, FSCALE, FYL2X, etc.
• Showing best practices for managing the x87 FPU stack
• Implementing common math operations like exp(x) or pow(a, b) manually

🧠 Assumptions

• The code is designed to run in a 16-bit real mode environment (e.g. MS-DOS)
• You have an 8086 or 8088 CPU with an 8087 numeric coprocessor installed
• You can assemble and link .asm files using tools like NASM.
• You can run the resulting binaries in a DOSBox, DOSBox-X, or real hardware (I have tested on an IBM 5150)

▶ How to compile and run

make
make rundosbox-x

List of programs

Example	Description
01	Exponential function
02	Square root function
03	Tan function