A Visual Computer Science Book

Under the
Code

From transistor to civilization. Eighteen chapters.

I The Physical World II THE SOFTWARE LAYER a packet's route III The Network redacted IV Data and Security five machines agree V The Modern Machine
I The Physical WorldCH 1–3 · BRIDGE → II The Software LayerCH 4–7 → III The NetworkCH 8–12 → IV Data and SecurityCH 13–15 → V The Modern MachineCH 16–18 →
5 PARTS· 18 CHAPTERS· 242 FIGURES· SELF-CONTAINED
BEGIN READING →
The Five Parts

From silicon to the cloud, one layer at a time.

IPART ONE
The Physical World
CHAPTERS 1 TO 3 · BRIDGE
Transistors, Boolean algebra, IEEE 754, the CPU, assembly, buffer overflows, and the hardware face of the kernel.
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IIPART TWO
The Software Layer
CHAPTERS 4 TO 7
The kernel as a real program: scheduling, virtual memory, filesystems, IPC. C's pointers, manual memory and undefined behaviour; C++'s classes and RAII; Python's interpreter and the GIL.
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IIIPART THREE
The Network
CHAPTERS 8 TO 12
Ethernet, IP, TCP, BGP, DNS, TLS, HTTP, JavaScript and the browser. From a packet on a wire to a page in a browser tab.
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IVPART FOUR
Data and Security
CHAPTERS 13 TO 15
SQL and the relational model. Cryptography from Caesar to post-quantum. The unified security chapter that turns every attack we have foreshadowed into one working theory.
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VPART FIVE
The Modern Machine
CHAPTERS 16 TO 18
Parallelism, the cloud, distributed consensus. The epilogue that synthesises the entire arc and hands the reader the four disciplines to take into the rest of computing.
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Full Contents

Eighteen chapters, one Bridge.

I
The Physical World
CHAPTER 01
The Machine Beneath Everything
CHAPTER 02
The Algebra of Switches
CHAPTER 03
The Language the CPU Speaks
BRIDGE
The Boundary
II
The Software Layer
CHAPTER 04
The Code That Owns the Machine
CHAPTER 05
C: The Language That Built Everything
CHAPTER 06
C++: When C Needed to Think in Objects
CHAPTER 07
Python: The Language That Chose Humans Over Machines
III
The Network
CHAPTER 08
The Wire
CHAPTER 09
Packets: How the Internet Decided to Work
CHAPTER 10
TCP: The Problem of Reliability
CHAPTER 11
HTTP, DNS, TLS: The Web
CHAPTER 12
JavaScript: The Language That Shouldn't Have Worked
IV
Data and Security
CHAPTER 13
SQL and the Mathematics of Data
CHAPTER 14
Cryptography: The Math That Keeps Secrets
CHAPTER 15
Attack and Defence: How Systems Break
V
The Modern Machine
CHAPTER 16
Parallelism: When One Core Isn't Enough
CHAPTER 17
The Cloud: Distributed Systems at Scale
CHAPTER 18
Epilogue: What You Now See

"Future users of large data banks must be protected from having to know how the data is organized in the machine."

E. F. Codd, 1970

A self-contained book · open any part to begin

Keep your place across devices