Question

Assume a 4GB memory:
a) What are the lowest and highest addresses if memory is byte-addressable?
b) What are the lowest and highest addresses if memory is word-addressable, assuming a 16-bit word?
c) What are the lowest and highest addresses if memory is word-addressable, assuming a 32-bit word?

Answer 1

Ans->

4GB memory is equal to 2^32 bytes

a> For Byte addressable, The highest address would be one byte before the end that is 2^32 - 1 and the lowest address is 0.

Lowest address = 0

Highest address = 2^32 - 1

b> For word addressable, assuming a 16 bit word
a word is equal to 16 bits == 2 byte because 8 bits are in a byte. so if we have 2^32 bytes then we only have 2^31 words.
Lowest address = 0
Highest address = 2^31 - 1

c> For word addressable, assuming a 32 bit word
a word is equal to 32 bits == 4 byte because 8 bits are in a byte. so if we have 2^32 bytes then we only have 2^30 words.
Lowest address = 0
Highest address = 2^30 - 1