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Foundations — the machine and the toolkit

# The layer under everything — text, time, algorithms, the OS, the network, and version control — learned by building the tools instead of trusting them.

Pathsaved 2026-08-08updated 2026-08-09 #path#fundamentals#algorithms#linux#networking#git

Goal

Build the substrate every later path stands on: how computers represent text and time, how to reason about cost, what the operating system and the network actually do, and how the one tool used every single day works underneath. The method throughout is the KB's house method: read the concept, then build the thing until it stops being a diagram. Everything here pays compound interest — nothing in the later paths is learnable properly without it.

Modules

1. Text, correctly

2. Time, honestly

  • Read: Time, timezones & datetime.
  • Do: DST-safe scheduler.
  • Proof: the scheduler's acceptance suite passes — Kiritimati, the half-hour zone, both DST edges, a year of "daily at 02:30" without a double-fire; "how do we store a future meeting time?" is answered by the passing tzdb-update test, not a paragraph.

3. Algorithms & data structures

  • Read: Algorithms & data structures.
  • Do: Interview-prep track — structures-from-scratch milestones first; the full pattern ladder continues in the background for the whole curriculum (spaced re-solves included).
  • Proof: per the track's subject — patterns solved within quota, explained aloud inside 25 minutes.

4. The operating system

5. The network

  • Read: Networking fundamentals.
  • Do: Build a DNS resolver.
  • Proof: the resolver walks from a root server to an authoritative answer, checked against dig; its two annotated captures (the resolver's own walk, and a full TCP + TLS + HTTP exchange), plus a whiteboard walk of what happens between typing a URL and pixels (the network half; the browser half comes in the full-stack path).

6. Version control, beneath the porcelain

  • Read: Git internals.
  • Do: Write Yourself a Git.
  • Proof: two-way interop with stock git per the subject; you can recover a "lost" commit via the object store without the reflog.

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