ece124: add gates

docs/1b/ece124.md

@@ -4,6 +4,44 @@
 
 Please see [ECE 150: C++#Non-decimal numbers](/1a/ece150/#non-decimal numbers) for more information.
 
-## Logic gates
+## Binary logic
 
-!!! definition
+A **binary logic variable** is a variable that has exactly two states:
+
+- 0, or false (switch open)
+- 1, or true (switch closed)
+
+**Binary logic functions** are any function that satisfies the following type signature:
+
+```python
+BoolFunc = Callable[[bool | BoolFunc, ...], bool]
+```
+
+In other words:
+
+ - it must accept a number of booleans and/or other logic functions, and
+ - it must return exactly one boolean.
+
+These can be expressed via truth table inputs/outputs, algebraically, or via a logical circuit schematic.
+
+### Logical operators
+
+Operator precedence is () > NOT > AND > OR.
+
+The **AND** operator returns true if and only if **all** arguments are true.
+
+$$A\cdot B \text{ or }AB$$
+
+<img src="https://upload.wikimedia.org/wikipedia/commons/b/b9/AND_ANSI_Labelled.svg" width=200>(Source: Wikimedia Commons)
+
+The **OR** operator returns true if and only if **at least one** argument is true.
+
+$$A+B$$
+
+<img src="https://upload.wikimedia.org/wikipedia/commons/1/16/OR_ANSI_Labelled.svg" align="middle" width=200>(Source: Wikimedia Commons)</img>
+
+The **NOT** operator returns the opposite of its singular input.
+
+$$\overline A \text{ or } A'$$
+
+<img src="https://upload.wikimedia.org/wikipedia/commons/6/60/NOT_ANSI_Labelled.svg" width=200>(Source: Wikimedia Commons)</img>