thepentiumprocessor(編輯修改稿)
2025-08-13 17:38 本頁面
【文章內(nèi)容簡介】 Pentium Registers (cont’d) ? Control registers ? (E)IP 187。Program counter ? (E) FLAGS 187。Status flags – Record status information about the result of the last arithmetic/logical instruction 187。Direction flag – Forward/backward direction for data copy 187。System flags – IF : interrupt enable – TF : Trap flag (useful in singlestepping) 2022 To be used with S. Dandamudi, “Introduction to Assembly Language Programming,” Second Edition, Springer, 2022. ? S. Dandamudi Chapter 3: Page 14 Pentium Registers (cont’d) ? Segment register ? Six 16bit registers ? Support segmented memory architecture ? At any time, only six segments are accessible ? Segments contain distinct contents 187。 Code 187。 Data 187。 Stack 2022 To be used with S. Dandamudi, “Introduction to Assembly Language Programming,” Second Edition, Springer, 2022. ? S. Dandamudi Chapter 3: Page 15 Protected Mode Architecture ? Pentium supports two modes ? Protected mode 187。32bit mode 187。Native mode of Pentium 187。Supports segmentation and paging ? Real mode 187。Uses 16bit addresses 187。Runs 8086 programs 187。Pentium acts as a faster 8086 2022 To be used with S. Dandamudi, “Introduction to Assembly Language Programming,” Second Edition, Springer, 2022. ? S. Dandamudi Chapter 3: Page 16 Protected Mode Architecture (cont’d) ? Supports sophisticated segmentation ? Segment unit translates 32bit logical address to 32bit linear address ? Paging unit translates 32bit linear address to 32bit physical address ? If no paging is used 187。 Linear address = Physical address 2022 To be used with S. Dandamudi, “Introduction to Assembly Language Programming,” Second Edition, Springer, 2022. ? S. Dandamudi Chapter 3: Page 17 Protected Mode Architecture (cont’d) Address translation 2022 To be used with S. Dandamudi, “Introduction to Assembly Language Programming,” Second Edition, Springer, 2022. ? S. Dandamudi Chapter 3: Page 18 Protected Mode Architecture (cont’d) ? Index ? Selects a descriptor from one of two descriptor tables 187。Local 187。Global ? Table Indicator (TI) ? Select the descriptor table to be used 187。0 = Local descriptor table 187。1 = Global descriptor table ? Requestor Privilege Level (RPL) ? Privilege level to provide protected access to data 187。Smaller the RPL, higher the privilege level 2022 To be used with S. Dandamudi, “Introduction to Assembly Language Programming,” Second Edition, Springer, 2022. ? S. Dandamudi Chapter 3: Page 19 Protected Mode Architecture (cont’d) ? Visible part 187。 Instructions to load segment selector ?mov, pop, lds, les, lss, lgs, lfs ? Invisible 187。 Automatically loaded when the visible part is loaded from a descr
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