Question 8784 – Computer-Organization

The capacity of the RAM needed = 16K
Capacity of the chips available = 1K

No. of address lines = 16K/1K = 16

Hence we can use 4 × 16 decoder for this. But we were only given 2 × 4 decoders.

So 4 decoders are required in inner level as from one 2×4 decoder we have only 4 output lines whereas we need 16 output lines.

Now to point to these 4 decoders, another 2×4 decoder is required in the outer level.

Hence no. of 2×4 decoders to realize the above implementation of RAM = 1 + 4 = 5