سؤال

I was reading about bit array and this question came up in my mind. Why are most machines not able to address individual bits? Is it because of the DMA and because it would be too (memory/circuits) expensive to keep an address for each bit?

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المحلول

A bit is the smallest unit of storage in memory.
A byte is the smallest addressable unit of storage in memory.
It doesn't make sense to make the bit addressable as it can only contain a 1 or 0 i.e. true or false information unlike a byte which can carry meaningfull information (you can encode a character set based on one byte e.g. ASCII).
This is just an intuitive explanation. I assume there are other techical low level reasons, e.g. it doesn't make sense to access memory for just 1 bit (too costly), i.e. make a 1-bit memory bus instead of 8-16 or more bits etc

نصائح أخرى

It since if you save adress just for bytes, the adress length is smaller in 3 bits.

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