diff --git a/docs/1b/ece124.md b/docs/1b/ece124.md
index 6b1c363..dd053fe 100644
--- a/docs/1b/ece124.md
+++ b/docs/1b/ece124.md
@@ -38,7 +38,7 @@ The **OR** operator returns true if and only if **at least one** argument is tru
$$A+B$$
-
(Source: Wikimedia Commons)
+(Source: Wikimedia Commons)
The **NOT** operator returns the opposite of its singular input.
@@ -46,6 +46,29 @@ $$\overline A \text{ or } A'$$
(Source: Wikimedia Commons)
+The **NAND** operator is equivalent to **NOT AND**.
+
+$$\overline{A\cdot B}$$
+
+
(Source: Wikimedia Commons)
+
+The **NOR** operator is equivalent to **NOT OR**.
+
+$$\overline{A+B}$$
+
+
(Source: Wikimedia Commons)
+
+### NAND/NOR completeness
+
+NAND and NOR are **universal gates** — some combination of them can form any other logic gate. Constructions of other gates using only these gates are called **NAND-NAND realisations** or **NOR-NOR realisations**.
+
+This is useful in SOP as if two ANDs feed into an OR, all can be turned into NANDs to achieve the same result.
+
+!!! example
+ NOT can be expressed purely with NAND as $A$ NAND $A$:
+
+ 
(Source: Wikimedia Commons)
+
### Postulates
In binary algebra, if $x,y,z\in\mathbb B$ such that $\mathbb B=\{0, 1\}$: