Transcript:

Hi, students welcome back. So in the previous video. I explained about the segmentation. Now let us see the segmentation architecture, and with an example, so then you will understand what exactly the segmentation will perform in the concept of logical Idris and the physical address. So I explained that this Eggman Tation is a always a or the Sigmund will store in the logical unit. So this logical address contains two tuples two tuples, so that is the segment number or the name and the offset. So actually this in this segment, a teacher, you are having the segment table, it maps, two dimensions, so that is a physical address, two dimensions of the let me write that point segment table mat’s, two dimensional physical edges, so the segment table maps, two dimensional physical address, so each table in has each table entry has one is base and another is limit, so the segment table consisting of two address space. So that is one is a base and another is the limit, so the base is nothing, but it contains of starting physical address base contains, so just remember this terms, the base, the limit, which other terms that are present in the segment table base, holds the starting address, contains the starting physical address, so where the segment resides in memory so in this fist starting physical address segment resides in that memory and the limit, consisting of specifies, the length of the segment specifies the length of segment, So just remember this the segment table. So this is a sigma, this segment table consisting of base and limit, so this base holds starting the physical address so in which that segment is resides and the limit mentions the length length of the segment length of segment and address address of segment that is a starting address of the segment, so this completely call it as a segment table. Okay, so now let us see the segment table base register so here you are having some to some terms in the architecture that is the segment table base register. That is St B R. So what Stbr means segment table base register, so it points to thee. It points to the segment table’s, location, location in memory so exactly it holds now in the memory. You have to store the data. So this the segment table base register, so whatever. I said the base limit. So this is the base and this is the limit. So this base register segment table base register points to the segment table location in memory and Vira’s segment table length register means the limit. I am talking about the limit length register. So that is st. L R. H TL R MS. Segment table length register. So it indicates the number of indicates number of segments used by program indicates number of means the length of the segments indicates the number of segments used by program signal used by program. So you have to remember that the segment number that is the name? The segment number S is legal whenever it is legal if the segment is less than segment table length register. So whatever the segment that you are storing in the table that segment should be less than the total length of the segment table length register. Okay, now let us see the example of these segment table segmentation. Let me explain the example example of segmentation. So let us take. This is the user space and here you are having the segment table. Okay, and here you are having the physical memory, so the physical memory, thirsty and here you are having this segment table. That is the limit and base so limit holds the length of the segment and base is the starting address of that physicality segment and you are having the segments, so let us take different segments, So let us take the subroutine. Stack Square root is one of the function like, and let us take the symbol table and main program, so let us say this is a segment zero segment, one segment, two segment, three and segment four, so this is completely the user space that you call it as a logical address space, so the a logical address space consisting of all this segment name. Plaza offset. So these are the segments these segments when stored in the segment table segment table, so the limit is let us take suppose the length of that one segment that is his segment zero. The segment zero length is Tao Zi and the base address. Starting address is 1400 okay, and the next the length of the c-segment square root is let us take It is 400 and the base address. The starting physical address is the 6300 and the segment to the segment to limit is 400 and the starting that resists 4,300 and sigma3. The stack length of the stack segment is 1100 and the physical base address is 3200 and Sigmund for the symbol table limit is let us take it is thousand and base address is 4700 Okay, so each segment is having that address starting address of that means to where it has to store in the main program means a physical memory and the size of that segment, so this complete user program is divided into set of segments, the first whatever the program that I have written that will be divided into set of the segments that will be stored in logical address space, so each segment is having some length means the size of that segment and the starting address of that segment. Now let us come into the physical memory how it is stored in the physical memory. So first segment 0 so the segment 0 so the base address? The starting address of the segment 0 is 1400 So this is the segment 0 then what is the size of that segment? The length of the segment thousand, so fourteen thousand plus thousand two thousand four hundred. So the Sigma is zero stored in this location now? Coming to the next next size is three thousand two hundred. That is a segment three. So let us take the segment three. The starting address is 3200 and the limit the length of that is 1100 so just add 1100 to this, so it becomes four thousand three hundred. So the next address base address is 4,300 so here. The segment two has to be stored and the size of that segment is four hundred just for add four hundred to this 4,300 So then it becomes four thousand seven hundred. So next next Look, e minimum is four thousand seven hundred so already. It is there so just at segment for what is the size of this segment for that is the thousand, so just add thousand to this. It becomes five thousand. So the starting address is four thousand seven hundred and ending of that segment is five thousand seven hundred so next size is six thousand Three hundred So right somewhere here. Six thousand three hundred, and this is the segment one. So the limit is 400 so just add 400 to this six thousand seven hundred. So this is how each segment will be stored in the physical memory so adding the limit and the base, so which is present in the segment table, so then it’s stored in the physical memory. So let me explain the. Cygnet Ation Hardware. So that I’ll explain the next video, also with a simple example, so taking some segmentation hardware, thank you.