Suppose you want to build a memory with 4 byte words with a capacity of…

First, calculate the total number of addressable words. The memory capacity is $2^{21}$ bits, and each word is 4 bytes (32 bits). Total words = $2^{21} / 32 = 2^{16}$.

Next, analyze the chip specifications. Each RAM chip is 2K x 8 bits, meaning it has a depth of $2^{11}$ words.

To achieve the required depth, determine how many rows of chips are needed. Rows = Target Depth / Chip Depth = $2^{16} / 2^{11} = 2^5 = 32$.

Finally, determine the decoder requirements. To select one out of 32 rows, a decoder with $\log_2(32) = 5$ input lines and 32 output lines is required.