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I was reading my Systems Programming book and got to a chapter about Hardware organisation of Systems. This was first time me reading about Hardware organisation of Systems so I got really interested and try to understand as much as possible. This is the first time I understood the difference between 32 bit and 64 bit architectures. But Im still confused. As I understood Buses are the paralel lines that move information in computer for example from cpu to I/O bridge. But I didn't really get does each line in bus carry one bit or a whole byte? In other words does 32 bit system bus have 32 lines or it has just 4 parallel lines which transfer a single byte? or does 64 bit system have 64 parallel lins or 8 parallel lines? I tried to find the answer but couldn't find it.

does transfering 1 single 32 bit information look like this? 

---0--->          or like this  --01011100-->
---1--->                        --10000100-->
   .                            --11010111-->
   .                            --01011101-->
   32 times
   .
   .
---1--->
---1--->

P.S. I am a bit wasting time at looking in such a detail, but I really got interested.

GreedyAi
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1 Answers1

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If you have 32-bit parallel bus it indeed transfers 32 bits of data simultaneously (synchronously with clock). However, bus width is in general independent of whether system it is 32 or 64 bit system

Konstantin
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  • can you explain a bit more by meaning simultaneosly? So will like 32 bit system bus be 32 lines wide or it will be 4 lines wide? – GreedyAi Mar 29 '14 at 20:26
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    32-bit bus would contain 32 data lines + some more control lines (address, clock, chip select etc) depending on the bus type. Bus has frequency of operation, each clock cycle it can transfer 32 bits of data (there are cycles when user data isn't transmitted, their number and purpose depends on the bus type). Dont confuse bus width with whether system has 32-bit or 64-bit Memory address width. Please refer to the link for some more information http://en.m.wikipedia.org/wiki/64-bit_computing – Konstantin Mar 30 '14 at 03:10