NOR
NOR gate
A logic gate that inverts an inclusive-OR result.
Schematic
IEEE / ANSI · NOR3
ANSI three-input NOR gate
Three-input OR outline with an output bubble; the output is high only when all three inputs are low.
In plain English
What does ANSI three-input NOR gate mean?
The three-input NOR gate is the OR outline with three inputs and a bubble at the pointed output. The output is high only when all inputs are low. Triple three-input NOR packages provide the function and it is often used to create an all-clear signal.
A simple example
When all inputs are themselves active-low alarm lines, the same function may be easier to read as an AND outline with bubbled inputs. A consistent choice across the drawing set makes reviews quicker.
What the drawings help you do
The symbol does not show output drive strength or whether the output may be wired to others. Check the device type before connecting outputs together.
This particular reference
Three-input OR outline with an output bubble; the output is high only when all three inputs are low. An AND outline with three bubbled inputs is the De Morgan equivalent of this gate.
- Terminal
- An identified point where a conductor connects.
- Signal
- Electrical information passed between devices, rather than necessarily the main power supply.
- Schematic
- A drawing showing function and connections rather than physical appearance.
Read the source: SNx4HC27 triple 3-input NOR gates
IEEE / ANSI · OR outline with three inputs and an output bubble
Distinctive-shape form as used in IEEE/ANSI-style schematics and manufacturer data books. Independent educational drawing; exact standard geometry and compliance are not asserted. The counterpart is the matching functional concept; no equivalence of every detailed standard graphic is asserted.
Shown as an independently authored educational illustration. Use the cited publication and drawing legend to verify the required drafting form.
Schematic · NOR3
What it represents
The three-input NOR gate is the OR outline with three inputs and a bubble at the pointed output. The output is high only when all inputs are low. Triple three-input NOR packages provide the function and it is often used to create an all-clear signal.
When all inputs are themselves active-low alarm lines, the same function may be easier to read as an AND outline with bubbled inputs. A consistent choice across the drawing set makes reviews quicker.
The symbol does not show output drive strength or whether the output may be wired to others. Check the device type before connecting outputs together.
How to read it
- Look for the output bubble at the point of the outline.
- Check whether a De Morgan form is used elsewhere for the same signal.
Information to show or reference
- Show the output bubble clearly.
- Name the condition each input represents.
- Note the device section and pin numbers.
A distinction that matters
An AND outline with three bubbled inputs is the De Morgan equivalent of this gate.
Sources you can follow
These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.
SNx4HC27 triple 3-input NOR gates
Manufacturer documentation for triple three-input NOR gates.
About this graphic
This illustration was authored independently by Elora Grid to explain the concept. It is not reproduced from a customer drawing, an official standard graphic or a manufacturer CAD file. Its correspondence to an exact IEC or IEEE symbol identifier has not been certified.
SVG and DXF downloads contain this original artwork. DXF uses unscaled drawing units; a GA envelope supplies no product dimensions, clearances or fabrication information. Original artwork is available under CC BY 4.0. Third-party references retain their own terms.
Explore related references
NOR
ANSI NOR gate drawn as negative-input AND
AND outline with bubbled inputs, the De Morgan form of a NOR that reads as all inputs low gives a high output.
IEEE / ANSI
≥1
IEC NOR gate (rectangular form)
IEC ≥1 element with a negated output; the output is active only when none of the inputs are active.
IEC
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