I’m Cha Seojun, a systems programmer and independent researcher deeply focused on understanding how computers work at the lowest level.

My work explores everything from:

  • ARM Assembly and memory-level logic
  • Linux Internals, syscalls, and ELF binaries
  • Compilers & Toolchains — building from scratch in Common Lisp
  • Bare-metal hardware emulation using QEMU
  • FPGA-based CPU design with Verilog
  • System Hacking and reverse engineering real-world binaries

I’m not just building projects — I’m building understanding.

Why this blog exists

This blog is my personal lab notebook. It’s where I:

  • Document complex topics in a way that’s visually and logically clear
  • Share real engineering struggles and breakthroughs
  • Build public proof of work — one post, one project at a time

I believe the best way to learn is to build from scratch and break things along the way.

Currently Working On

  • From the Transistor
    Designing a CPU → writing an assembler, compiler, and OS → running a real shell and browser on FPGA.

  • ARM Assembly Tutorial
    A step-by-step ARMv4 assembly tutorial designed for low-level programmers.
    Covers instruction encoding, memory access, stack, branching, condition flags, and more — with hands-on examples and detailed explanations.

​ Services

I offer freelance development and consulting in the following areas:

  • Low-Level & Embedded Programming — ARM assembly, memory-mapped I/O, embedded C
  • System Internals & Analysis — Linux kernel, syscall tracing, ELF reverse engineering
  • Compiler & Toolchain Engineering — parsing, code generation, optimization
  • Reverse Engineering & Refactoring — legacy code analysis, modernization, debugging support

Although all my technical content is written in English for global reach and sharing, my freelance services are currently limited to Korean-speaking clients only. This is to ensure clear and effective communication for project success.

Interested in working together? Please fill out the following form so I can understand your needs:

Request a Service

I will review your submission and get back to you promptly.

Vision

I’m building toward becoming a world-class independent hacker and technical creator —
someone like George Hotz, but in my own way, in Korean and global hacker culture.

Contact

Thanks for stopping by. Stay curious, and keep building.