74155: Dual 1-of-4 Data Distributor

This dual package may be used to provide two 1-low-out-of-4 outputs or may be used to send input data to one selected output of four, the remaining three staying high. Both halves of the circuit are identically addressed.

The output address is selected with the 1 and 2 Address inputs. For instance, a 1 low and a 2 low input selects output No. 0 on both sides of the circuit.

If the Data input is made high and the Enable input low on circuit No. 1, the selected output address goes low. If the Data input is made low and the Enable is made low on circuit No. 2, the selected output address goes low.

If the Enable is made low on circuit No. 1, the complement of the input data appears at the selected output. If the Enable is made low on circuit No. 2, the input data appear at the selected output.

Note that the two halves of this circuit are not identical. Side No. I inverts the data. Side No. 2 does not.

The circuit is converted into a 1-of-8 data distributor by connecting the two Data input lines together and using them as a 4-address line. If both Enables are low, the selected 1-of-8 output goes low. If both Enables are paralleled and fed data, the data are routed to the selected output.

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