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Abhishek Singh
09/08/05 09:16
Read: 981 times
Bilaspur
India


 
#100820 - irrelevent: irrelevent?
Responding to: Andy Neil's previous message
Andy Neil said:


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.


exactly thats why i called it x86 memory


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!


what is proved?


All the memory ever sees is a 20-bit address - it knows nothing about segmentation!


?? processor is executing the code so rollover ocuurs in processor!


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...


ok but here op talks about the IP roll over all those register (SS, DS ES (FS GS)) cant be used to execute code, the instruction fetch always occurs corresponding to the CS. On execution, procvessor incremets IP. if rollover occurs all it will start executing the CS:0000 i.e. same segment offset zero. it will not jump to 0000:0000, that was my question.


Abhishek



List of 16 messages in thread
TopicAuthorDate
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      

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