RAM
IEC random-access memory (RAM)
IEC element marked RAM with address grouping, a write control input and A-labelled data inputs and outputs.
IEC
IEC · Am
IEC address dependency (A)
Dependency label A used on memory symbols to show which word of an array the address inputs select.
In plain English
What does IEC address dependency (A) mean?
A dependency is used mainly on memory symbols. Address inputs are grouped, often with the binary grouping symbol, to produce internal affecting inputs A0 to An. Data inputs and outputs labelled A then act only on the selected word, so one symbol can represent an entire array.
A simple example
Reading a memory symbol, start with the address grouping to see the range, then follow the A-labelled data terminals. TI's public overview shows an array of latches forming a small random-access memory using this method.
What the drawings help you do
The notation does not give access time or organisation details beyond word count and width. Those are in the device data.
This particular reference
Dependency label A used on memory symbols to show which word of an array the address inputs select. M dependency selects modes, while A selects which of several identical words is accessed.
- 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: Overview of IEEE Standard 91-1984: explanation of logic symbols (SDYZ001A)
IEC · Address inputs grouped to produce A affecting inputs; affected terminals labelled A
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 · Am
What it represents
A dependency is used mainly on memory symbols. Address inputs are grouped, often with the binary grouping symbol, to produce internal affecting inputs A0 to An. Data inputs and outputs labelled A then act only on the selected word, so one symbol can represent an entire array.
Reading a memory symbol, start with the address grouping to see the range, then follow the A-labelled data terminals. TI's public overview shows an array of latches forming a small random-access memory using this method.
The notation does not give access time or organisation details beyond word count and width. Those are in the device data.
How to read it
- Find the address grouping and its range first.
- Terminals labelled A act on the selected word only.
Information to show or reference
- Show the address bus with its binary grouping.
- Label affected data terminals with A.
- State word count and width in the outline title.
A distinction that matters
M dependency selects modes, while A selects which of several identical words is accessed.
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)
A (address) dependency and memory array examples.
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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