What happens when the words transfered on the bus are smaller than its width?

So what happens if we're transfering lots of 8 bit words in a 32 bit bus? Does each bus cycle only transfers 8 bit at the time, wasting the other 24 lines of the bus? Or does it transfer 4 words in each bus cycle?

I would say "it depends":

• most likely you ask for 8 bits to be retrieved and you get 8 bits and ignore the other 24 lines;

• if you know you're dealing with sequential data, that you want to consider bytewise, you could retrieve 4 bytes at a time, but you'll have to split or handle the retrieved 4 bytes in code.

On specific architectures you have alignment considerations.

Specifically addressing your question, no, it is very unlikely a system would retrieve 4 words in each cycle only to then "split" them into single words to process, without a program catering for that itself.

StackExchange Computer Science Q#42897, answer score: 4