# IEC address dependency (A)

Canonical URL: https://eloragrid.ai/symbols/iec-address-dependency-a
Publisher: Elora Grid
Updated: 2026-10-28
Lookup label: Am
Drawing use: Schematic
Reference families: IEC, Manufacturer

## Symbol convention

Convention: IEC
Form: 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.

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.

### Terms

- 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.

Concept diagram: Identify the device and form → Read the connections and state → Check the equipment reference
A guide to reading this reference. The original symbol illustration and its drawing notes appear below; these boxes are not a wiring diagram.

- [Overview of IEEE Standard 91-1984: explanation of logic symbols (SDYZ001A)](https://www.ti.com/lit/ml/sdyz001a/sdyz001a.pdf)


## 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.

## Important distinction

M dependency selects modes, while A selects which of several identical words is accessed.

## Facts

- Affecting input at 1: Permits action (address selected)
- Typical device: RAM or ROM
- Artwork scope: Original educational illustration; consult the applicable standard and the selected device documentation for the exact graphic

## Public references

- [Overview of IEEE Standard 91-1984: explanation of logic symbols (SDYZ001A)](https://www.ti.com/lit/ml/sdyz001a/sdyz001a.pdf) — Texas Instruments. A (address) dependency and memory array examples.

## Graphic scope

Independent original educational concept illustration by Elora Grid. Not a certified standards graphic or manufacturer footprint. Unitless; not to scale. Original artwork licence: https://creativecommons.org/licenses/by/4.0/. Publisher material is linked only.