Project ForgeDigital Logic
Combinational & Sequential Circuits
GATE 2007
Medium
How many 3-to-8 line decoders with an enable input are needed to construct a 6-to-64 line decoder without using any other logic gates?
- A7
- B8
- 9
- D10
Explanation
Use 1 first-level 3-to-8 decoder (fed by the top 3 address bits) to generate 8 enable signals, each driving one of 8 second-level 3-to-8 decoders (fed by the bottom 3 address bits) — giving all 64 outputs. Total decoders = 1 + 8 = 9.
Source: GATE CS 2007 (2007)
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