Talk:Segment descriptor

message: I removed this text: "The memory is subdivided into segments. A segment in the x86 architecture can be from 1 byte to 4Gbyte long. It can start at any base address in memory. Each segment has a segment descriptor associated with it." It's unsourced, and per this discussion there is a significant concern about copyvios in unsourced material from the India Education Program. Mike Christie (talk - contribs -  library) 01:16, 28 October 2011 (UTC)
replies: text: This text was copied verbatim from the following source "Introduction to the 80386" by Intel, which is a pdf document freely available at bitsavers.  — Preceding unsigned comment added by 83.31.72.91 (talk) 13:52, 2 January 2022 (UTC)

text: Moreover the sentence is true in protected mode only, whereas in real mode segments can be up to 64 kB long only, and always start at 16 byte boundaries.  — Preceding unsigned comment added by 83.31.72.91 (talk) 14:01, 2 January 2022 (UTC)
thread_title:  Removed unsourced text 

message: This article has been found to be edited by students of the Wikipedia:India Education Program project as part of their (still ongoing) course-work. Unfortunately, many of the edits in this program so far have been identified as plain copy-jobs from books and online resources and therefore had to be reverted. See the India Education Program talk page for details. In order to maintain the WP standards and policies, let's all have a careful eye on this and other related articles to ensure that no material violating copyrights remains in here. --Matthiaspaul (talk) 12:51, 31 October 2011 (UTC)
thread_title:  Look out for possible copyright violations in this article 

message: I've moved the following text here from the article as it was almost completely unsourced; it also has some formatting problems which should be fixed if it's to be returned.  I've enclosed it in a collapse template as it contains section headings.  See WT:IEP for an explanation of the reasons for this proactive removal of information.  Mike Christie (talk - contribs -  library) 00:03, 1 November 2011 (UTC)
thread_title:  Section moved from article 

message: A 16-bit segment register stores a 16-bit selector. It points to a segment descriptor in GDT or in LDT. 
==Bit specification:==
1.	Upper 13 bits:
     The upper 13 bits of a selector points to one of the 8192  descriptors in the descriptor table. 
2.	Bit T1 (bit 2):
     It selects the GDT or LDT depending upon its value.
                 T1=1	LDT
                 T1=0	GDT
3.	Requestor Privilege Level (RPL):
     It indicates the privilege level of the task which is requesting the memory access.
 
	The three types mentioned above are memory arrays of variable length. They have size in the range 8 bytes (single descriptor) to 64 kbytes (8192 descriptors, 8 bytes each). The upper 13 bytes of a selector are used as an index into the descriptor table.
==	Access of Operand Using GDT :==
  DS	        The operand in memory is accessed in DS. Its upper 13 bits point to the descriptor.
  EIP	        It contains offset of the  accessed operand
  DESCRIPTOR	Descriptor in GDT stores the base address of  the data segment.
  GDTR	        It contains base address of the GDT.
 
(fig)
==	Access of Operand Using GDT :==
The LDT is used for a particular task. But it can be shared between the tasks as well. GDT contains a descriptor pointing to the base of the LDT. The register LDTR points to the LDT descriptor within the GDT. A LDT descriptor copy is stored in 64-bit register in CPU.
(fig)
== Not just Intel ==
The article has a generic title, but it only discusses segment descriptors in one architecture. I'm not sure whether it would be better to have separate articles for Segment descriptor (x86) and Segment descriptor, or to make the current text a section within a generic article. The generic text should note that there is some variation in nomenclature, e.g., data descriptor and segment descriptor,
 segment descriptor word,
 segment-table entry.
 Shmuel (Seymour J.) Metz Username:Chatul (talk) 15:23, 12 January 2021 (UTC)
thread_title: 	Descriptor Selection:

message: The article has a generic title, but it only discusses segment descriptors in one architecture. I'm not sure whether it would be better to have separate articles for Segment descriptor (x86) and Segment descriptor, or to make the current text a section within a generic article. The generic text should note that there is some variation in nomenclature, e.g., data descriptor and segment descriptor,
 segment descriptor word,
 segment-table entry.
 Shmuel (Seymour J.) Metz Username:Chatul (talk) 15:23, 12 January 2021 (UTC)
thread_title:  Not just Intel