 Hello friends, myself, Narshan Pandit, assistant professor, department of computer science and engineering from Walton Institute of Technology, Soulapur. So, today we are going to discuss about segmented display file and display file compilation. So, at the end of this session student will be able to describe segmented display file and display file compilation. So, in this first we will see introduction after that segment format, segment attribute, segment states, segment command and display file compilation. So, we know application programmer uses high level graphics package which include various images and to view entire image or part of image we require various attribute, we need to organize image information in particular manner as the structure of display file do not satisfy our requirement of weaving an image. So, in order to achieve this display we need to divide into segments. So, segments are nothing but small part of image and these segments are stored in display device as a linked list of blocks and each segment represent a logical separate portion of an image and segment should include in a refresh cycle for display onto the screen. So, we are having starting address after that segment 1, segment 1 is linked to segment 2, segment 3 and so on till segment n. So, the figure shows simple conceptual model of display process where we are having application data in which it contains segmented display file. After that we need to define segments which is a display processor. After that from here segments are transformed onto a display file that is to refresh display cycle. After that these segments are sent to a display controller that is to generate display. After that these are mapped to display device that is displayed on display device. So, this is nothing but simple conceptual model of display process. So, segmented display file is read by display processor the term segment is used for a unit of picture that is named for modification purpose and programmer require to recognize the existence of display file as stored representation of display image. So, it is simply collection of display file instruction representing graphics primitive which can be manipulated by instruction. So, in this way we are having the segment format first we are having segment name after that display point of field that is visibility point of field. So, visibility point of field is linked to output parameter and end of segment point of field it is linked to next segment point of field and next segment point of field is linked to the next segment. So, this is basic segment format which includes segment parameters and output parameters. So, segment attributes we are having visibility. So, if we set visibility with the segment ID V then the segment is posted if it is visible and unposted if it is invisible that is posted is nothing but it is displayed and unposted it is nothing but it is not displayed that is it is invisible. Next attribute is priority set segment priority with the ID and P is nothing but priority highlight set highlight with the ID of the segment and H is nothing but the segment is highlighted or it is kept normal after that size position and orientation set segment transformation. So, this can be done by transformation and this transformation is applied with the help of transformation matrix on the segment ID. So, these are the two states segment states pented and unpented. So, pented marks all posted segment as visible and unpented marks all unposted segment as invisible. So, pented segments are visible and unpented segments are invisible that is these segments are not sent to the display device. Segment commands so, with the ID we can create the segment with the segment ID we can close the segment and by providing ID we can delete or rename them segment ok. So, for renaming the segment we require old ID and new ID that is old ID is replaced by new ID. Next is display file compilation so, now we have created the segments that is images divided into smaller sets that is nothing but segment. Now we need to display those segments one after the another in display file compilation we need to construct a display file compiler and this ensures uninterrupted refresh for flicker free and maintains constant refresh during all display modification that is segment one after that segment two is displayed after that segment three. So, it is nothing but a three segment display file. The corruption of file occurs when display fails to represent valid sequence of instruction. So, that is why we use double buffering where a new segment is constructed in unused memory leaving the old version in a display file. So, here we can see so, this is in the discontinuity in the display file ok. So, we are having segment one after that segment two and after that we are adding new segment and after this new segment is mapped to segment three and here we are leaving the free space that this is nothing but the discontinuity in a display file. So, when a new version is closed or posted the old version is replaced by display file and space is vacated for further use. So, here you can see the figure shows segment one after that you are it is mapped to old segment two, old segment two is mapped to segment three after that new segment three and now I need to add new segment two before new segment three and I need to vacate old segment two. So, here directly I can link segment one to new segment two and after that new segment two is linked to segment three. So, this can be achieved with the help of double buffering and corruption in display file. So, the display file compiler at frequent interval needs block of unused memory in order to construct the new segment and discard block of memory which has no further use and a free storage allocation system is required. So, here you can see fragmenting effect of free storage of double buffering. So, this is one of the problem of double buffering where we are having old segment after that new segment again old segment two again new segment. So, this old segments are creating some free space after every new segment we are having free space. So, this is nothing but fragmenting effect of free storage of double buffering. So, when new segment is added, a new segment is separated with the main free block and factored segments are created and these factored segments are more troublesome. That is whenever a largest large size image we want to fit in the free block. So, it is it won't fit in that free block as the size of free block will be smaller than the image size. So, that size will be wasted. So, to eliminate this problem, we always fetch largest available block of memory and later return the unused portion and the vacated block should be placed on a temporary free storage list and added to the main list only after end of the refresh cycle. So, that all free space is collected all together and it can be utilized for new segments. So, this figure shows amalgamating free blocks by garbage collection. So, here you can pause the video and answer the question analyze the problem with double buffering. So, double buffer increase discontinuity in display file where each segment is followed by next consecutive segment or point of and it creates factored segment which are more troublesome. So, these are the references which are used to create this video.