Email: Password: Remember Me | Create Account (Free)

Back to Subject List

Old thread has been locked -- no new posts accepted in this thread
Andy Neil
09/08/05 08:47
Read: 1021 times

#100816 - Irrelevant?
Responding to: Abhishek Singh's previous message
Abhishek Singh said:
the x86 memory is segmented and any adress has two parts.

Not quite.

Memory is memory - it is addressed in the normal way.

It's not the memory itself that is segmented - it's just the way the x86 works with it internally.

The x86 is a 16-bit processor, so all its internal registers & data paths are 16 bits wide.
But the x86 has a 20-bit address space; the Segment:Offset business is just the way it manages to get 20 bits out of two 16-bit registers!
All the memory ever sees is a 20-bit address - it knows nothing about segmentation!

offset is stored in IP(instruction pointer) and segment in the CS

The x86 has a whole bunch of registers that can be used as Segment registers, and plenty of others that can be used as offsets...

List of 16 messages in thread
Micro Controller powered?      Rupesh Deenadayalan      09/06/05 00:10      
   bible study time?      Andy Neil      09/06/05 01:22      
      Reboot ?      Rupesh Deenadayalan      09/08/05 00:53      
         See reply (Off-Topic)      Andy Neil      09/08/05 01:41      
   Not A PC      Neil Kurzman      09/06/05 09:35      
      Reboot doubt      Rupesh Deenadayalan      09/08/05 00:35      
         Off Topic.      Andy Neil      09/08/05 00:47      
            Rampant code execution      Andy Neil      09/08/05 01:00      
            CS:IP      Abhishek Singh      09/08/05 06:45      
               Irrelevant?      Andy Neil      09/08/05 08:47      
                  irrelevent: irrelevent?      Abhishek Singh      09/08/05 09:16      
                     TOTALLY irrelevant, at least at a '51 fo      Erik Malund      09/08/05 09:39      
                        Already established!      Andy Neil      09/08/05 10:37      
                     Wrong      Andy Neil      09/08/05 11:46      
                        You Sure?      Neil Kurzman      09/09/05 12:45      
                           If you want a proper answer...      Andy Neil      09/10/05 01:52      

Back to Subject List