superharrydude09
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I was learning about address bus, and that if it was 32 bit, then there would be 2^32 maximum addressable locations, which is roughly 4 GB. What is confusing me is that 32 bits is 4 bytes, so why does 32 bit convert to 4GB in this case.
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gcseeeman
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(Original post by superharrydude09)
I was learning about address bus, and that if it was 32 bit, then there would be 2^32 maximum addressable locations, which is roughly 4 GB. What is confusing me is that 32 bits is 4 bytes, so why does 32 bit convert to 4GB in this case.
32 bits can represent 2^32 different values. If they are addresses, then 32 bits can represent 2^32 different 32-bit addresses.

When you say 32 bits is 4 bytes, you are talking about the information held directly in those 32 bits; when you talk about the 32-bit addresses that can be represented by those 32 bits (or by 4 bytes), you are talking about the information that can be held in the 2^32 (or 2^8 * 2^8 * 2^8 * 2^8) different addresses (e.g. 2^32 different bytes, as seems to be the case in the 4 GiB example you give).

Does that help at all?
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RogerOxon
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(Original post by superharrydude09)
I was learning about address bus, and that if it was 32 bit, then there would be 2^32 maximum addressable locations, which is roughly 4 GB. What is confusing me is that 32 bits is 4 bytes, so why does 32 bit convert to 4GB in this case.
A byte (more formally, an octet) is 8 bits, so a byte of address can access 256 locations. Therefore, if you want to convert n bytes of address to number of locations, it's 256^n={2^8}^n=2^{8n}. It's not a linear relationship - 2 bytes of address only allows for 64KB.

Note that memory chips don't typically offer byte accesses. They have a much wider data bus - 256b (16B), or more, so some of the byte address lines actually serve to address the byte within the data read.
Last edited by RogerOxon; 4 weeks ago
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