CCB
IEC common-control block
Notched block above an array; its inputs apply to every element below unless dependency notation limits them.
IEC
IEC · COE
IEC common-output element
Element with a double top line that produces one output depending on all elements of an array above it.
In plain English
What does IEC common-output element mean?
TI's public overview of IEEE Std 91 describes the common-output element as having a double line at its top. It sits beneath an array of identical elements and produces a single output that depends on all of them, such as a combined carry or an all-equal flag. It must carry its own general additional drawing mark to say what function it performs.
A simple example
On data-book style drawings the common-output element saves repeating a gate for every bit. When reading it, look at the additional drawing mark in the element (for example & or ≥1) and remember that its inputs come from each element above as well as any external inputs drawn on its side.
What the drawings help you do
The double line only signals the structural role. Without the additional drawing mark inside, the function is undefined, and the drawing should not be accepted in that state.
This particular reference
Element with a double top line that produces one output depending on all elements of an array above it. The common-control block has a notched outline at the top of an array and distributes inputs downwards; the common-output element collects results at the bottom.
- 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: Overview of IEEE Standard 91-1984: explanation of logic symbols (SDYZ001A)
IEC · Element below an array with a double line at its top, carrying a general qualifier
Qualifying-symbol and dependency conventions as explained in TI's public overview of IEEE Std 91-1984, which incorporates IEC 617-12 work. Independent educational drawing; not certified IEC geometry or an IEC database identifier.
Shown as an independently authored educational illustration. Use the cited publication and drawing legend to verify the required drafting form.
Schematic · COE
What it represents
TI's public overview of IEEE Std 91 describes the common-output element as having a double line at its top. It sits beneath an array of identical elements and produces a single output that depends on all of them, such as a combined carry or an all-equal flag. It must carry its own general qualifier to say what function it performs.
On data-book style drawings the common-output element saves repeating a gate for every bit. When reading it, look at the qualifier in the element (for example & or ≥1) and remember that its inputs come from each element above as well as any external inputs drawn on its side.
The double line only signals the structural role. Without the qualifier inside, the function is undefined, and the drawing should not be accepted in that state.
How to read it
- Look for the qualifier inside the double-line element; it defines the function.
- Inputs come from every element in the array above.
Information to show or reference
- Draw the double line clearly at the top of the element.
- Include a general qualifier.
- Show any additional external inputs on the side.
A distinction that matters
The common-control block has a notched outline at the top of an array and distributes inputs downwards; the common-output element collects results at the bottom.
Sources you can follow
These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.
Overview of IEEE Standard 91-1984: explanation of logic symbols (SDYZ001A)
Describes the common-output element and its double-line feature.
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.
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