The chip select logic for a certain DRAM chip in a memory system design is shown below. Assume that the memory system has 16 address lines denoted by A15 to A0

Q. The chip select logic for a certain DRAM chip in a memory system design is shown below. Assume that the memory system has 16 address lines denoted by A₁₅ to A₀. What is the range of addresses (in hexadecimal) of the memory system that can get enabled by the chip select (CS) signal?

(A) C800 to CFFF

(B) CA00 to CAFF

(C) C800 to C8FF

(D) DA00 to DFFF

Ans: C800 to CFFF

Solution:

A15 A14 A13 A12 A11 A10 A9 … …. A0

1    1   0   0   1   0   0 … …. 0  = C800

|-Chip select (CS)-| …   … …. 1  = C801

1    1   0   0   1   …   … …. .  = …

1    1   0   0   1   1   1 … …. 1  = CFFF