Final answer:
The maximum main memory size for a 32-bit microprocessor is capped at 4 GB, as it can address up to 2^32 bytes.
Step-by-step explanation:
In reference to a microprocessor with a word size of 32 bits, the maximum main memory size that can be addressed is determined by the number of unique addresses that can be represented by those 32 bits. Since each bit can be a 0 or a 1, there are 232 possible addresses. When calculating the maximum size, we consider each addressable unit as a byte, so the maximum memory size that can be directly addressed is 232 bytes, or 4,294,967,296 bytes.
This total amount of addressable memory equates to 4 gigabytes (GB), given that one GB equals 1,024 megabytes (MB) and one MB equals 1,024 kilobytes (KB). Therefore, with a 32-bit microprocessor, the size of the usable main memory is capped at 4 GB.