Address decoder ― 7485

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An address decoder is a circuit whose task is to signal to its device that the processor has generated its address on the bus.

When the HIGH state appears at the system output, it means that the decoder has detected that the address of its device is on the bus.

Instruction - The bus consists of 8 address lines A0 - A7, but in this example the decoder only listens on 4 lines.
• Click on the bus line - change the state to LOW/HIGH.
• Click on pins B3..B0 to change their state.
• When A3..A0 (from bus) = B3..B0 → A=B = HIGH.
• LOW (green) = 0,    HIGH (red) = 1.