The
No-Nonsense
Guide to Assembly
From CPU anatomy to a 512-byte bootable operating system. Every program runs, every chapter has answers, and the whole thing is free.
No email. No paywall. Just the book.
What You'll Build
Six programs, zero libraries.
An Interactive Calculator
Reads two integers and an operator, prints the answer. No C library, just syscalls and the digit tricks that make numbers printable.
A Professional Hex Dumper
A working clone of xxd: 16 bytes per line, offsets, and an ASCII sidebar. Then it inspects its own binary and finds the ELF magic.
A Unix Shell
fork, execve, wait. The three syscalls behind every shell on your machine, in a working prompt-to-prompt loop.
A Web Server
Serves a live HTML page with a visitor counter over HTTP, written entirely in assembly. Verified with a real curl session.
A Custom malloc
Your own memory allocator with block headers, splitting, and free-list reuse. The layer underneath every malloc you've ever called.
A Bootable Operating System
The final chapter. A 512-byte boot sector that paints the screen and reads your keystrokes with no operating system underneath at all.
Inside the Book
55+ original diagrams. Every program verified.
The programs in this book were assembled and run on real Linux. The debugger sessions, HTTP exchanges, and the boot screenshot are real captures, not mockups.
Table of Contents
6 parts. 30 chapters.
The Machine
- 1 The Anatomy of a Computer
- 2 Inside the x86-64 CPU
- 3 The Workshop: NASM, ld, and Your First Program
- 4 Moving Data and Addressing Memory
- 5 Arithmetic, Logic, and the Division Trap
Control Flow, the Stack, and Functions
- 6 Branching: cmp, Flags, and Jumps
- 7 The Hardware Stack
- 8 Functions and the System V ABI
- 9 Strings, Arrays, and the String Engine
- 10 Capstone: An Interactive Calculator
Talking to the Operating System
- 11 Command-Line Arguments
- 12 Files and File Descriptors
- 13 Dynamic Memory: Asking the Kernel for RAM
- 14 Structs and Linked Lists
- 15 Mixing Assembly and C
- 16 NASM Macros and Project Organization
Performance
- 17 Floating-Point and SIMD
- 18 Branchless Programming and Cycle Counting
- 19 Concurrency and Atomic Operations
- 20 Inline Assembly in C and Rust
Under the Surface
- 21 How the CPU Reads Your Code: Instruction Encoding
- 22 Debugging and Reverse Engineering with GDB
- 23 Stack Smashing and Its Defenses
- 24 Position-Independent Code and Shared Libraries
- 25 Raw Terminal Mode
Real Software, from Scratch
- 26 A Professional Hex Dumper
- 27 A Unix Shell
- 28 Sockets and a Web Server
- 29 A Custom malloc and free
- 30 Booting Into the Void
About the Author
Fire the translator.
Read it online, print it, share it, remix it. The text is CC BY 4.0 and the code is MIT. Errata go straight to GitHub.
377 pages · 30 chapters · every program verified · free, forever