An accessible guide to our digital infrastructure, explaining the basics of operating systems, networks, security, and other topics for the general reader.

Most of us feel at home in front of a computer; we own smartphones, tablets, and laptops; we look things up online and check social media to see what our friends are doing. But we may be a bit fuzzy about how any of this really works. In Bits to Bitcoin, Mark Stuart Day offers an accessible guide to our digital infrastructure, explaining the basics of operating systems, networks, security, and related topics for the general reader. He takes the reader from a single process to multiple processes that interact with each other; he explores processes that fail and processes that overcome failures; and he examines processes that attack each other or defend themselves against attacks.

Day tells us that steps are digital but ramps are analog; that computation is about “doing something with stuff” and that both the “stuff” and the “doing” can be digital. He explains timesharing, deadlock, and thrashing; virtual memory and virtual machines; packets and networks; resources and servers; secret keys and public keys; Moore's law and Thompson's hack. He describes how building in redundancy guards against failure and how endpoints communicate across the Internet. He explains why programs crash or have other bugs, why they are attacked by viruses, and why those problems are hard to fix. Finally, after examining secrets, trust, and cheating, he explains the mechanisms that allow the Bitcoin system to record money transfers accurately while fending off attacks.

Mark Stuart Day was Chief Scientist at Riverbed Technology for a decade and is currently Visiting Lecturer at MIT. With more than thirty patented inventions, he has also made technical contributions at Dropbox, IBM, Cisco, Digital, and BBN.

Preface ix
Acknowledgments xiii
1 Introduction 1
I Single Process
2 Steps 5
3 Processes 17
4 Names 31
5 Recursion 41
6 Limits: Imperfect Programs 49
7 Limits: Perfect Programs 65
II Interacting Processes
8 Coordination 81
9 State, Change, and Equality 89
10 Controlled Access 101
11 Interrupts 111
12 Virtualization 123
13 Separation 135
14 Packets 151
15 Browsing 155
III Unstoppable Processes
16 Failure 177
17 Software Failure 199
18 Reliable Networks 207
19 Inside the Cloud 217
20 Browsing Revisited 241
IV Defending Processes
21 Attackers 253
22 Thompson's Hack 263
23 Secrets 273
24 Secure Channel, Key Distribution, and Certificates 289
25 Bitcoin Goals 307
26 Bitcoin Mechanisms 315
27 Looking Back 335
Index of Metaphors and Examples 337
Subject Index 341