Digital Logic Toolkit

Digital Logic Toolkit — XNOR gate

Source
https://digitallogictoolkit.com/xnor-gate/
Printed

A = 1, B = 1 — XNOR gate

introagreement gives 1

Answer

output 1

Why this example is worth doing

Both inputs the same gives 1, which is the whole gate: XNOR is an equality detector. Opening on the both-high row rather than the both-low row is deliberate, because a student arriving from the XOR page has just seen that row give 0 and the contrast is the fastest possible explanation of what the extra bubble does.

Try your own input in the XNOR gate. Truth table, symbol and algebraic form for A ⊙ B, the equality detector.

How the answer is reached

The probed row

A = 1, B = 11— Row 3 of 4.

Truth table

Truth table — columns #, A, B, A ⊙ B
#ABA ⊙ B
0001
1010
2100
3111

Compare with

Open this example in the XNOR gate

The field arrives filled in with this example’s input.

Note:

Notation this page assumes

  • Symbols: · is AND, + is OR, ⊕ is XOR, a prime or an overline is NOT. The field also takes ∧ ∨ ¬ ~ ! & | and the words.
  • Operator precedence, tightest first: NOT, then AND (including juxtaposition), then XOR/XNOR, then NAND/NOR, then OR, then IMPLIES, then IFF.
  • Gate symbols follow whichever standard the header toggle is set to: ANSI/IEEE Std 91-1984 distinctive shapes, or IEC 60617-12 rectangles.

Sources

  • ANSI/IEEE Std 91-1984, Graphic Symbols for Logic Functions
  • IEC 60617-12, Graphical Symbols for Diagrams — Binary Logic Elements