What are the best resources and projects for learning how computers work under the hood?

For programming languages, check out Crafting Interpreters. It walks you through lexical analysis, parsing, an interpreter, bytecode, and a virtual machine, with practical implementations rather than just theory. I’d do it after learning some computer architecture, then try writing a tiny stack-based language or assembler of your own.

For operating systems, use Operating Systems: Three Easy Pieces and actually complete the exercises. Computer Systems: A Programmer’s Perspective is also excellent for connecting C programs to assembly, memory, processes, linking, and hardware. For the hardware foundation, Code: The Hidden Language of Computer Hardware and Software is very readable, while computer architecture and digital logic textbooks provide more depth.

A great starting point is Nand2Tetris. You build a complete computer from NAND gates upward, including the CPU, memory, assembler, virtual machine, and a simple compiler. Since you’re studying electronics, the hardware sections should be especially approachable. After that, a structured curriculum such as OSSU Computer Science or Teach Yourself Computer Science can fill in the broader theory.

If you prefer interactive projects, Turing Complete and Logisim Evolution are useful for experimenting with logic gates, registers, an ALU, and a simple CPU. Ben Eater’s breadboard computer project is another good hands-on route. Once you understand how instructions execute, try writing a small shell in C, an assembler, or a minimal emulator. You don’t need to abandon your current shell project—use it as a practical way to learn processes, system calls, files, and memory while studying the lower layers.