Machine Code Isn't Scary

Original Article ↗ Hacker News Discussion ↗

Demystifying Machine Code & Early Experiences

  • Many recall early 8‑bit days (BBC Micro, ZX81, Spectrum, TRS‑80, CoCo, Amiga) where BASIC was obvious, but machine code initially felt like an unreachable “secret decoder ring.”
  • The “click” often came from better explanations (books like CODE, advanced OS guides, SICP‑style thinking): realizing complex behavior is “just” data in registers/memory plus OS/hardware calls.
  • Several describe hand‑assembling hex and POKEing it into memory or using DOS debug.com; once you see bytes ↔ instructions, machine code stops being mystical and becomes “just tedious.”

Hardware, ISAs, and Instruction Encodings

  • Long subthread on how hardware implements branches: disagreement over whether “hardware executes both sides”; clarified as specific circuit patterns (muxes, ALUs, speculative execution) vs the abstract ISA model.
  • Discussion of immediate encodings on AArch64, RISC‑V, x86; big constants require multiple instructions or special patterns. Variable‑length x86 vs fixed‑length RISC designs are contrasted.
  • Some argue instruction encodings are mostly niche knowledge (assembler/disassembler writers); understanding the ISA and memory/branch behavior matters more than bit‑level formats.

JITs, Emulators, and Low‑Level Projects

  • One poster describes building a Forth that directly emits machine code for x86‑64, AArch64, and RISC‑V; finds a simple non‑optimizing JIT surprisingly approachable.
  • Others mention mapping Lisp or toy languages directly to WebAssembly or assembly, and using tools like Capstone for disassembly.
  • Emulator authors highlight opcode‑decoding recipes (e.g., Z80) and note that for actual programming, a macro assembler is far more practical than typing hex.

Should Assembly Be a First Language? (Big Disagreement)

  • Pro side: instructions are simple, map cleanly to “sequences, conditions, loops,” and expose why higher‑level languages exist. Toy ISAs, microcontrollers, and simulators give immediate, tangible feedback (LEDs, simple games).
  • Contra side: assembly is unstructured, verbose, and brittle; it doesn’t resemble the control structures students will actually use, and it distracts from problem‑solving with hardware details few will need.
  • Critics warn it can build wrong mental models for modern CPUs/compilers, and kill motivation in beginners whose goals are “make games/sites,” not “understand bits.” Many advocate starting high‑level, then introducing assembly later for context.

Assembly in Practice: Production vs Hobby

  • Embedded and OS developers still use small, targeted assembly for special instructions, calling conventions, or extreme performance, and read disassembly frequently for debugging and perf work.
  • Others with heavy production ASM experience report it’s slow and painful for general development; C (or higher) is almost always more productive, with compilers usually generating better overall code, especially on complex modern CPUs.
  • For obscure MCUs, compilers can be poor, making hand‑written assembly dramatically faster and smaller; this keeps low‑level skills relevant in some niches.

Abstraction, Mental Models, and Education

  • Several posters frame computing as “Input → Computation → Output,” or “Programs = Data + Instructions,” and say adopting this model made all levels—from machine code to OSs—much less intimidating.
  • There’s tension between two educational philosophies:
    • Start from hardware/assembly to ground abstractions.
    • Start from pure problem‑domain languages and only later show what runs underneath.
  • Consensus points: machine code itself isn’t inherently scary; good explanations, tooling (monitors, simulators, debuggers), and clear goals determine whether it feels empowering or pointless.