3-input OR, A = 0, B = 0, C = 1 — OR gate

coreone high input dominates

Answer

output 1

Why this example is worth doing

One high input out of three is enough. OR's absorbing value is 1, exactly mirroring AND's absorbing 0, and the page presents the pair as duals rather than as two facts. The practical form is the interrupt line: a wide OR over many request signals asserts when any single device wants attention, which is why OR trees sit at the top of interrupt controllers and why the output tells you something happened but not what.

Try your own input in the OR gate. Truth table, symbol and algebraic form for A + B, with a live two-input toggle.

How the answer is reached

The probed row

A = 0, B = 0, C = 11Row 1 of 8.

Truth table

Truth table — columns #, A, B, C, A + B + C
#ABCA + B + C
00000
10011
20101
30111
41001
51011
61101
71111

Compare with

Open this example in the OR 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