Book · 1999
Code: The Hidden Language of Computer Hardware and Software
by Charles Petzold
A retired software engineer builds a computer from telegraph relays and flashlights, one chapter at a time, until you understand what a CPU actually does.
What does Reddit think of Code: The Hidden Language of Computer Hardware and Software?
That concentration makes sense: the book exists for people who write code but have never understood what happens below the interpreter. The sub's recurring pitch is specific — this is what you read before you can explain why computers use binary, or after two years of programming when you realize the hardware layer is a black box. The ↑270 comment calls it the best book for non-programmers learning computing from scratch. The ↑380 commenter admits parts went over their head — the electricity and history chapters draw the most complaints — but finished it and recommended it anyway. r/ExperiencedDevs shows 7 mentions, mostly in lists alongside Nand2Tetris, treating it as foundational substrate rather than practical reference. Sentiment across all subs is broadly positive.
Community feedback & reader fit
Themes
- · Bottom-up computer architecture from first principles
- · Hardware fundamentals for software developers
- · History of computing from telegraph to microprocessor
- · Binary arithmetic and Boolean logic
- · How CPUs execute instructions
Common praise
- + The progression from telegraph relays to logic gates to CPU makes previously arbitrary abstractions feel inevitable.
- + The ↑270 commenter calls it the best non-programmer introduction to computing that exists.
- + Readers who finish it report that low-level concepts in other CS books stop feeling like magic.
Common criticism
- − The electricity and circuits chapters run long before anything resembling computing appears — a reported friction point in multiple threads.
- − The ↑380 commenter admits parts went over their head, and that honest caveat is the most-upvoted full endorsement the book gets.
Who it's for
If you write code every day and couldn't explain what happens between source file and CPU, this is the book r/learnprogramming points you toward. Self-taught developers who skipped formal CS get the most out of it. CS graduates with architecture coursework will find the first half redundant. Push past the circuits section or don't start — the payoff on the other side is real, but it requires finishing.
Mentions over time
Which Reddit comments matter for Code: The Hidden Language of Computer Hardware and Software?
Top-upvoted quotes across the subreddits where this book is mentioned. Click through to read the full thread.
“What I would call the classics: * Design Patterns - Elements of Reusable Object-Oriented Software * Code Complete * Rapid Development * The Pragmatic Programmer * The Mythical Man-Month * Operating Systems Design and Implementation * Refactoring - Improving the Design of Existing Code * The Algorit…
“Here's the list, for anyone interested in just that: 1. The Pragmatic Programmer by David Thomas & Andrew Hunt (67% recommended) 2. Clean Code by Robert C. Martin (66% recommended) 3. Code Complete by Steve McConnell (42% recommended) 4. Refactoring by Martin Fowler (35% recommended) 5. Hea…
“I 100% recommend Code: The Hidden Language of Computer Hardware and Software. Parts of it did go over my head, because it talks a lot about the history of computers and a lot of technical mumbo jumbo regarding electricity. I enjoyed it though, I read…
“Programming is about formally expressing processes. If this happens, do that. Do this N times. When this happens, do X and also stop doing Y. Or maybe stop Y before doing X. Thinking like a programmer isn't about code so much as thinking formally about processes. "Formally"? Consider that mat…
“Code: The Hidden Language of Computer Hardware and Software I'm surprised no one has mentioned this yet. This is the best book fo…
“Here's my list of the classics: **General Computing** * But How Do It Know? - The Basic Principles of Computers for Everyone * The Elements of Computing Systems: Building a Modern Computer from First Principles * […
“Thank you for your the effort, looks like a great list of resources but I really dislike that website, so here's a list of every chapter and its links/description in case someone else hates it too **YOU SHOULD GIVE THE WEBSITE A TRY THOUGH, SINCE IT HAS SOME HANDY FUNCTIONALITY AND OP HAS SPE…
“Your assessment of the fundamentals is correct. + Code flow + Variables + Loops + Branches (conditionals) + Input/Output + Data Structures (not complete fundamentals) You obviously fall short on the *problem solving* aspect of programming. What you have to learn is to abstract *code* from *algo…
Convinced? Pick up Code: The Hidden Language of Computer Hardware and Software
Readers also mention
Books that share discussion threads with Code: The Hidden Language of Computer Hardware and Software — counted from the comments, not curated.
Think Like a Programmer
V. Anton Spraul
V. Anton Spraul's guide to breaking down any programming problem before writing a single line of code — written for learners who know syntax but freeze at blank pages.
Structure and Interpretation of Computer Programs
Harold Abelson
MIT's 1985 Scheme textbook that 319 Reddit commenters have recommended and a noticeably smaller number have finished.
The Pragmatic Programmer
Andy Hunt
Two veterans hand you a checklist for the craft: don't write code you don't need, own your tools, and fix the broken window before someone else does.
Clean Code
Robert C. Martin
The book 536 Reddit threads cite when arguing about naming variables — revered by beginners, argued over by seniors.
The Art of Computer Programming
Donald E. Knuth
Donald Knuth's multi-volume monument to algorithms: the book programmers cite in library lists and almost nobody finishes.
The Unicorn Project
Gene Kim
The Phoenix Project retold from the developer's chair: same burning company, different seat at the fire.
Code: The Hidden Language of Computer Hardware and Software — frequently asked
Is Code: The Hidden Language still worth reading in 2026?+
Yes, for anyone who hasn't internalized how hardware works. The fundamentals don't expire. r/learnprogramming has cited it 141 times, and it appeared there as recently as March 2026. The second edition updated examples without changing the structure, so the ↑270 recommendation for non-CS beginners still holds.
What does Reddit think of Code: The Hidden Language compared to Nand2Tetris?+
Reddit treats them as different tools rather than competitors. Code is narrative and historical; Nand2Tetris is hands-on and project-based. r/learnprogramming lists them alongside each other in the ↑257 classics thread, and r/ExperiencedDevs groups them in the same breath when discussing foundational computing texts. Neither substitutes for the other.
Does Code: The Hidden Language work for people with no electrical engineering background?+
Mostly. The ↑380 r/learnprogramming commenter says parts went over their head — specifically the electricity and hardware sections — but finished it and found it worthwhile. The circuits chapters are the reported friction point. Readers who push through report the payoff on the architecture side is real.
Should experienced developers bother with Code: The Hidden Language?+
Depends on what you missed. It gets sent to juniors and career-changers. If you have a CS degree, you've probably covered this ground. If you don't, and you've been wondering about the bottom of the stack, it's the right book.