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How the Machine Thinks

Before you write a line of Java, you should know what a computer actually is: switches, numbers built out of switches, and a set of tools that will not think for you.

Not on the exam · read it first anyway

AP Computer Science A · members' unit

How the Machine Thinks is behind a locked door

Units in AP Computer Science A are for people taking the course. Getting in takes a link or a key — signing in on its own doesn't do it.

What's in this unit · 15 min read

  1. What makes something a program
  2. Gates: how switches make a decision
  3. How can wires and electricity think?
  4. Build the tables yourself
  5. Counting in binary
  6. Hexadecimal, and why anyone bothers
  7. Your tools
  8. How you turn work in
  9. Before the next unit

9 quick checksabstraction ladderstepperlogic gate scroller

1 Sign in

With your school Google account. This is how your work reaches the gradebook — it doesn't open the unit by itself.

2 Get in

Open the class link your teacher posted — that's the usual way, and it enrols you on the spot. Or paste an access key if you were handed one.

A key unlocks this browser and keeps your progress here; signing in keeps it with you across devices. Either way the key itself is only ever checked as a hash. Manage all of this on your account, read what signing in stores, or go back to AP Computer Science A.

Sources

  • College Board — AP Computer Science A Course and Exam Description, Effective Fall 2025