TI486 Microprocessor - Al Kossow's Bitsavers

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Appendix B TI486 Cache Flush B.1 General Cache Invalidation B.1.1 When the FLUSH bit in CCRO is set, the FLUSH input invalidates the entire contents of the TI486 internal cache when asserted low. This may be used to assure that data stored in the TI486 internal cache does not differ from data stored in system memory. Additionally, the cache may be invalidated by execution of the 486-compatible invalidate instructions (lNVD,WBINVD) or in response to a Hold Acknowledge state if the BARB bit in CCRO is set. The method chosen for invalidating the TI486 internal cache may be different, depending on whether or not the system has a serial secondary cache. Invalidation methods are described for systems with and without a serial secondary cache. Cache Invalidation for Systems With No Secondary Cache or a Parallel Secondary Cache Method 1 Method 2 Figure 8-1. FLUSH Logic When the only cache memory in the system is the TI486 internal cache, or when the secondary cache has a parallel (or look-aside) architecture, there are two general methods of invalidating the cache and maintaining cache coherency. Invalidate the TI486 every time the CPU enters a HOLD state. By setting the BARB bit in CCRO, automatic cache flush occurs when the TI486 is placed in a HOLD state. If the chip set does not support hidden refresh, this may lead to very frequent cache invalidation, since it will put the CPU in hold during DRAM refresh cycles, which occur approximately every 15 J..ls. If the chip set supports hidden refresh, this may be an acceptable solution, since the cache will only be invalidated during DMA or bus master reads from or writes to memory. Invalidate the TI486 internal cache when a DMA or bus master writes to system memory. This requires external hardware to drive the TI486 FLUSH input when DMA or bus masters are detected writing to system memory. This can be done with the simple circuit shown in Figure B-1. The circuit will generate an active-low FLUSH to the CPU every time a HOLD state is entered (defined by HLDA = 1) and memory write occurs (defined by MEMW = 0). MEMW ~>----_----, (from ISA bus) -----v FLUSH HLDA _________ (to T1486) (from CPU) D- 8-1
General Cache Invalidation 8.1.2 Cache Invalidation for Systems With A Serial Secondary Cache Figure 8-2. FLUSH Logic In a system with a serial (or look-through) secondary cache, flushing the cache cannot be accomplished by setting the BARB bit in CCRD because bus arbitration occurs between the serial cache controller and the system. This allows the CPU to continue executing out of cache. The secondary cache controller arbitrates the bus between itself and DMA controllers or bus masters and asserts HLDA to the chip set when the bus has been granted. Each time a DMA or bus master write is detected, the FLUSH pin on the TI486 must be asserted. The circuit shown in Figure B-2 may be used. Note that the HLDA signal is now generated by the secondary cache controller rather than the CPU. This is the preferred solution since in many cases with secondary serial caches, the CPU is not put in HOLD so that it can continue execution from cache while DMA or bus master activity is occurring on the system bus. MEMW ~>-_---, (from ISA bus)-----V D- FLUSH HLDA_________ (to T1486) (from eC) 8-2 TI486 Cache Flush
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.TEXAS INSTRUMENTS TI486 Microproce
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TI486 Microprocessor Reference Guid
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Preface Read This First About This
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About This Manual Appendix D Orderi
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Contents 1 Product Overview .......
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Contents 5.5 AC Characteristics . .
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1-1 TI486SLC/E Functional Block Dia
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Figures 4-27 SUSP Initiated Suspend
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Tables 5-3 Absolute Maximum Ratings
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Product Overview 1-1
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Chapter 1 Product Overview Features
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1.2 Differences Between the TI486SL
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Tl486SLCIE Overview Figure 1-2. TI4
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Tl486DLCIE Overview 1.4 TI486DLC/E
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TI486DLCIE Overview The TI486DLC/E
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Power Management / System Managemen
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Programming Interface 2-1
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Chapter 2 In this chapter, the inte
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Processor Initialization Table 2-1.
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Instruction Set Overview 2.2 Instru
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Register Set 2.3 Register Set There
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Register Set Pointer and Index Regi
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Register Set 2.3.1.2 Segment Regist
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Register Set 2.3.1.3 Instruction Po
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Register Set 2.3.2 System Register
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Register Set 2.3.2.1 Control Regist
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Register Set 2.3.2.2 Descriptor Tab
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Register Set Table 2-6. Segment Des
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Register Set During task switching,
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Register Set The CCRO register (Tab
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Register Set Table 2-9. TI486DLCIE
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Register Set Table 2-12. ARR 1-ARR4
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Register Set 2.3.2.6 Test Registers
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Register Set Table 2-14. TR6 and TR
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Address Spaces 2.4 Address Spaces T
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Address Spaces 2.4.2 Memory Address
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Address Spaces Figure 2-21. Real Mo
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Address Spaces Figure 2-24. Paging
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Interrupts and Exceptions 2.5 Inter
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Interrupts and Exceptions 2.5.3 Int
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Interrupts and Exceptions Table 2-2
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System Management Mode 2.6 System M
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System Management Mode Figure 2-29.
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System Management Mode The new SMM
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System Management Mode During SMM o
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Protection The Current Privilege Le
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Virtual 8086 Mode 2.9 Virtual 8086
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TI486SLC/E Bus Interface 3-1
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Chapter 3 TI486SLC/E Bus Interface
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Overview Table 3-1. TI486SLCIE Sign
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Overview Table 3-2. Terminal Functi
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Overview 3.1.1 Bus Cycle Definition
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Overview Table 3-5 shows the state
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Functional Timing Figure 3-3. Bus A
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Functional Timing 3.2.2.1 Bus Cycle
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Functional Timing Non-Pipelined Wai
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Functional Timing Because of the de
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Functional Timing Pipelined Wait St
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Functional Timing Initiating and Ma
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Functional Timing Figure 3-12. Comp
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Functional Timing Figure 3-13. Inte
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Functional Timing Shutdown Indicati
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Functional Timing Figure 3-17. Pipe
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Functional Timing As shown in Figur
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Functional Timing Figure 3-19. Requ
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Functional Timing Figure 3-22. 8MI
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Functional Timing HALT Initiated Su
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Functional Timing 3.2.12 Float Figu
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TI486DLC/E Bus Interface 4-1
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Chapter 4 TI486DLC/E Bus Interface
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Overview Table 4-1. TI486DLCIE SIgn
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Overview Table 4-6. Signal States D
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Overview 4.1.2 Power Management 4.1
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Functional Timing 4.2 Functional Ti
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Functional Timing The TI486DLC/E da
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Functional Timing Non-Pipelined Rea
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Functional Timing Initiating and Ma
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Functional Timing Figure 4-8. Faste
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Functional Timing Figure 4-9. Vario
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Functional Timing Once a pipelined
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Functional Timing 4.2.3 Bus Cycles
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Functional Timing Pipelined Cycles
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Functional Timing LOCK is activated
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Functional Timing 4.2.6 Halt and Sh
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Functional Timing Figure 4-17. Pipe
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Functional Timing Figure 4-19. Non-
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Functional Timing The TI486DLC/E sa
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Functional Timing 4.2.9 Hold Acknow
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Functional Timing 4.2.10 Coprocesso
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Functional Timing 4.2.12 Power Mana
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Functional Timing Stopping the Inpu
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Electrical Specifications 5-1
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Chapter 5 Electrical Specifications
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ElectricalConnecnons It is recommen
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Recommended Operating Conditions 5.
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DC Electrical Characteristics Table
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AC Characteristics Figure 5-2. TI48
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AC Characteristics Table 5-9. AC Ch
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AC Characteristics Table 5-11. AC C
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____ AC Characteristics 5.5.3 RESET
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Mechanical Specifications 6-1
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Chapter 6 Mechanical Specifications
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Pin Assignments Table 6-1. TI486SLC
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Pin Assignments Figure 6-3. TI486DL
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Package Dimensions 6.2 Package Dime
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Thermal Characteristics 6.3 Thermal
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Instruction Set 7-1
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Chapter 7 Instruction Set This sect
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Instruction Fields 7.2 Instruction
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Instruction Fields 7.2.5 reg Field
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Instruction Fields Table 7-7. mod r
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Instruction Fields 7.2.11 sreg3 Fie
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Clock Count Summary 7.4 Clock Count
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--- --;.J -L 01 Table 7-17. Instruc
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I . ~ -.....J Table 7-17. Instructi
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Table 7-17. Instructions, Opcodes,
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Table 7-17. Instructions, Opcodes,
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-....J N (J.) Table 7-17. Instructi
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I I i I i Table 7-17. Instructions,
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...... ...... '" Table 7-17. Instru
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-....J N co Table 7-17. Instruction
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"-.I ~ Table 7-17. Instructions, Op
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Page 266 and 267: U Appendix A TI486 SMM Pro rammer's
Page 268 and 269: SMM Implementation A.2 SMM Implemen
Page 270 and 271: Figure A-1. SMM Memory Space Header
Page 272 and 273: SMM Implementation 6) NMI is the on
Page 274 and 275: Instruction Summary A.4 Instruction
Page 276 and 277: Instruction Summary A.4.3 Resume No
Page 278 and 279: Instruction Summary A.4.6 Save LDTR
Page 280 and 281: 8MI Handler Example A.5 SMI Handler
Page 282 and 283: 8MI Handler Example execute_halt: C
Page 284 and 285: 8MI Handler Example COMMENT A The T
Page 286 and 287: 8MI Handler Example arrl arr2 arr3
Page 288 and 289: .MODEL SMALL . STACK .386P INCLUDE
Page 290 and 291: Testing/Debugging SMM Code sgdt COM
Page 292 and 293: Testing/Debugging SMM Code i*******
Page 294 and 295: TI486 Power Management Features A.7
Page 296 and 297: Detection of Tl486 CPU A.9 Detectio
Page 298 and 299: Detection of SMM Capable Version A.
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Page 302 and 303: A.11 SMM Feature Comparison SMM Fea
Page 304 and 305: SMM Instruction Macros COMMENT A Co
Page 306 and 307: SMM Instruction Macros SMM Instruct
Page 308 and 309: A.14 Format of Data Used by SVDC/RS
Page 310 and 311: Altering SMM Code Limits A.1S Alter
Page 312 and 313: SMM Errata A.16 SMM Errata The foll
Page 316 and 317: Appendix C TI486 BIOS Modification
Page 318 and 319: Introduction Some example assembler
Page 320 and 321: Appendix D Ordering Information 0.1
Page 322: ~TEXAS INSTRUMENTS Printed in U.S.A
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