Stage 1 of 8 · 7 lessons · ~4 weeks

How a computer runs a program

Binary, logic, the CPU, memory and the path from source code to machine instructions. Every other subject in this roadmap sits on top of this picture.

Start: Binary, hexadecimal and integers

Lessons· one lesson for each topic, in this order

Do this

Convert ten numbers between decimal, binary and hex by hand, including negative numbers in two's complement.
Print 0.1 + 0.2 in two languages and explain the output in writing.
Build the first two or three Nand2Tetris projects (gates and the adder) in the online simulator.
Compile a small C function with optimisations off and read its assembly output on Compiler Explorer.
Write a recursive function that overflows the stack on purpose and note the depth it reached.
Draw the memory layout of a running program: code, globals, stack and heap.
Draw your source-to-process diagram and explain it aloud to a classmate in five minutes.

Start with· follow one of these

CourseFree
CS50: Introduction to Computer Science
Harvard University · Beginner
The first weeks in C teach binary, memory, pointers and the stack and heap with excellent problem sets
VideoFree
Crash Course Computer Science
CrashCourse · Beginner
Short videos from transistors to CPUs and memory; the quickest way to see the whole picture

Practise

Nand to Tetris: Build a Modern Computer from First Principles
Build the gates, ALU and CPU yourself in a simulator, so the layers stop being abstract

Keep handy

roadmap.sh: Computer Science
A topic map of the whole CS curriculum to check your coverage against, stage by stage
Computerphile
Short explanations from researchers when one idea, such as floating point, will not click

Also worth your time

Understanding Memory Leaks: Causes and How to Avoid Them (opens in a new tab)Read
Connects the stack and heap to the leaks you will actually meet in garbage-collected code
The C Programming LanguageGo deeperPaid
The classic short book on C, the language closest to the machine model this stage describes

Before moving on: A one-page diagram, in your own words, that follows a small C or Python program from source file to running process: compilation or interpretation, memory layout, the fetch, decode, execute loop and where the data sits in the memory hierarchy.

Tauseef's advice

Most students skip this because it feels like first-year material, then struggle in operating systems because they never understood memory. Spend two focused weeks here. Build a few chips in Nand2Tetris if you can; nothing else makes the layers click as fast.