Contents

1. Introduction
2. History: how machines learned to add
3. Lesson 1. Gates and the half adder: 1 + 1 = 10
   1. 1.1. The idea: adding one digit
   2. 1.2. Building
   3. 1.3. Check
   4. Lesson 1 paste (Cmd+I)
4. Lesson 2. The full adder and 4 bits: the carry runs through the digits
   1. 2.1. The idea: column addition
   2. 2.2. Building
   3. 2.3. Check
   4. Lesson 2 paste (Cmd+I)
5. Lesson 3. Negative numbers and subtraction: two's complement
   1. 3.1. The idea: numbers on a circle
   2. 3.2. Flags
   3. 3.3. Building
   4. 3.4. Check
   5. Lesson 3 paste (Cmd+I)
6. Lesson 4. 8 bits and comparison: CMP is subtraction
   1. 4.1. The idea: two halves
   2. 4.2. The idea: comparison is subtraction
   3. 4.3. Building
   4. 4.4. Check
   5. Lesson 4 paste (Cmd+I)
7. Lesson 5. The ± calculator: the minus on a lamp, the magnitude on the display
   1. 5.1. The idea: the magnitude is one more subtraction
   2. 5.2. Building
   3. 5.3. Check
   4. Lesson 5 paste (Cmd+I)
8. Lesson 6 (bonus). Decimal math: add six
   1. 6.1. The idea: a digit in four bits
   2. 6.2. Why the display is in HEX mode
   3. 6.3. Building
   4. How to set the digits
   5. 6.4. Check
   6. Lesson 6 paste (Cmd+I)
9. Summary
10. All the parts
11. Instructions in pictures