Looking at the datasheet of 74LS145 and 74LS147, determine if their input/output

Question

Looking at the datasheet of 74LS145 and 74LS147, determine if their input/outputs are active-LOW or active-HIGH. 1. 74LS 145 BCD-to-Decimal decoder has inputs and 1) (active-LOW/active-HIGH) (active-LOW/active-HIGH) outputs. 2) 74LS147 Decmila-to-BCD encoder has_(active-LOW/active-HIGH) inputs and (active-LOW/active-HIGH) outputs. 2. What is meant by "priority encoding" for the encoder circuit you designed? 3. If converting octal to binary, which chip may be used? How about for hexadecimal to binary?

Explanation / Answer

1. 1) active-HIGH, active-LOW

2) active-LOW, active-LOW

2. Priority encoding means responding to just one input in accordance with some priority system, among all those that may be simultaneously HIGH. The most common priority system is based on the relative magnitudes of the inputs; whichever decimal point is the largest, is the one that is encoded.  

3. octal to binary : 74138 and Hexadecimal to binary : 74154

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