minimum 4*16 line decoders required to realize 8*256 line decoders are

Question

i m getting 16 but the answer is 17 .please explain

Answer 1

for 8*256 decoder 1 would required in first level and 16 in second level  ....the best way to apprach this question is starting from 2nd level see 256 output lines so 256/16 decoder now to select one of 16 decoder we neead one 4:16 decoder so ans is 1+16=17

Comments

... got it 1 decoder will be used to select one of the enable input of 16 deoders ...

thanku

Answer 2

pls have a look at

similarly in your question,one 4;16 decoder will be used to select the one of 16 decoder in second level