Internal Architecture, 21264/EV68A Microarchitecture | Compaq

2

Internal Architecture

This chapter provides both an overview of the 21264/EV68A microarchitecture and a sys- tem designer’s view of the 21264/EV68A implementation of the Alpha architecture. The combination of the 21264/EV68A microarchitecture and privileged architecture library code (PALcode) defines the chip’s implementation of the Alpha architecture. If a certain piece of hardware seems to be “architecturally incomplete,” the mi ssing functionality is implemented in PALcode. Chapter 6 provides more information on PALcode.

This chapter describes the major functional hardware units and is not intended to be a detailed hardware description of the chip. It is organized as follows:

•21264/EV68A microarchitecture

•Pipeline organization

•Instruction issue and retire rules

•Load instructions to R31/F31 (software-directed instruction prefetch)

•Special cases of Alpha instruction execution

•Memory and I/O address space

•Miss address file (MAF) and load-merging rules

•Instruction ordering

•Replay traps

•I/O write buffer and the WMB instruction

•Performance measurement support

•Floating-point control register

•AMASK and IMPLVER instruction values

•Design examples

2.121264/EV68A Microarchitecture

The 21264/EV68A microprocessor is a high-performance third-generation implementa- tion of the Compaq Alpha architecture. The 21264/EV68A consists of the following sections, as shown in Figure 2–1:

•Instruction fetch, issue, and retire unit (Ibox)

•Integer execution unit (Ebox)

21264/EV68A Hardware Reference Manual

Internal Architecture 2–1

Image 29

Compaq specifications Internal Architecture, 21264/EV68A Microarchitecture

Contents

Compaq Computer Corporation Shrewsbury, Massachusetts Revision/Update Information 21264/EV68A Hardware Reference Manual Table of Contents Cache and External Interfaces Hardware Interface Internal Processor Registers Privileged Architecture Library Code Mffpcr Mtfpcr Initialization and Configuration Testability and Diagnostics Error Detection and Error HandlingElectrical Data Thermal Management 21264/EV68A Boundary-Scan Register Alpha Instruction Set Glossary Index 21264/EV68A-to-Bcache Pin Interface Figures 10-2 Type 2 Heat Sink Tables Xiv VDD Idcpower Page Audience ContentPreface Documentation Included by Reference Abbreviations Terminology and ConventionsFor example W1S W1CAddresses Aligned and Unaligned Data Units Signal NamesDo Not Care External Undefined Do not care. a capital X represents any valid value Page Introduction IntroductionArchitecture Addressing ArchitectureInteger Data Types Floating-Point Data Types 21264/EV68A Microprocessor Features 21264/EV68A Microprocessor Features 21264/EV68A Microprocessor Features Internal Architecture Internal Architecture21264/EV68A Microarchitecture Virtual Program Counter Logic Instruction Fetch, Issue, and Retire Unit21264/EV68A Microarchitecture Branch Predictor 21264/EV68A Block Diagram Global Predictor Local Predictor Instruction-Stream Translation Buffer Choice Predictor Register Rename Maps Integer Issue QueueInstruction Fetch Logic Hwret Floating-Point Issue Queue Retire Logic Integer Execution UnitException and Interrupt Logic Integer Execution Unit-Clusters 0 PERR, MINxxx, MAXxxx, UNPKxx, PKxx 10Internal Architecture Floating-Point Execution Unit 21264/EV68A contains two onchip primary-level caches External Cache and System Interface UnitOnchip Caches 12Internal Architecture Memory Reference UnitData Cache Pipeline Organization Pipeline OrganizationSrom Interface Miss address file MAF Dstream translation buffer DTB 14Internal Architecture Stage 0 Instruction FetchStage 1 Instruction Slot Stage 2 Map Stage 3 Issue Instruction Issue Rules Instruction Issue RulesPipeline Aborts Ebox and Fbox pipelines begin execution Instruction Name, Pipeline, and Types Instruction Group Definitions FTOIS, Ftoit Ebox SlottingITOFS, ITOFF, Itoft Instruction Group Definitions and Pipeline Unit U U L E L U E E L L E U Instruction Class Latency in Cycles Instruction LatenciesHwmfpr 20Internal Architecture Minimum Retire Latencies for Instruction Classes Instruction Retire RulesInstruction Retire Rules Retire of Operate Instructions into R31/F31 Retire of Operate Instructions into R31/F31Floating-Point Divide/Square Root Early Retire BSR/JSR Load Instructions to R31 and F31 Load Instructions to R31 and F31Prefetch with Modify Intent LDS Instruction Instructions Retired Without Execution Special Cases of Alpha Instruction Execution Special Cases of Alpha Instruction ExecutionPrefetch, Evict Next LDQ and Hwldq Instructions Load Hit Speculation 10 Pipeline Timing for Floating-Point Load Instructions 26Internal Architecture Floating-Point Store InstructionsCmov Instruction Memory and I/O Address Space Instructions Memory and I/O Address Space InstructionsMemory Address Space Load Instructions 2 I/O Address Space Load Instructions 28Internal Architecture Memory Address Space Store InstructionsRules for I/O Address Space Load Instruction Data Merging Rules for I/O Address Space Store Instruction Data Merging 4 I/O Address Space Store Instructions MAF Memory Address Space Merging Rules MAF Memory Address Space Merging RulesInstruction Ordering Mbox Order Traps Replay TrapsReplay Traps Write Buffer and the WMB Instruction 12 I/O Write Buffer and the WMB InstructionOther Mbox Replay Traps Memory Barrier MB/WMB/TB Fill Flow WMB Instruction Processing MB Instruction Processing 12 TB Fill Flow Example Sequence TB Fill Flow13 TB Fill Flow Example Sequence 34Internal Architecture Floating-Point Control Register Performance Measurement Support-Performance CountersPerformance Measurement Support-Performance Counters Floating-point control register Fpcr is shown in Figure 36Internal Architecture Floating-Point Control Register14 Floating-Point Control Register Fields Amask and Implver Instruction Values Amask and Implver Instruction Values Design Examples Design ExamplesAmask Implver 12 Typical Uniprocessor Configuration Page Hardware Interface 21264/EV68A Microprocessor Logic SymbolHardware Interface 21264/EV68A Microprocessor Logic Symbol 21264/EV68A Microprocessor Logic Symbol 21264/EV68A Signal Names and Functions 21264/EV68A Signal Names and FunctionsSignal Pin Types Definitions 21264/EV68A Signal Descriptions Dcokh Pllvdd TestStatH 21264/EV68A Signal Descriptions by Function SysVref Domain SysAddInL140 Pin Assignments Pin List Sorted by Signal NamePin Assignments AC1 Pllvdd 10Hardware Interface AA5 12Hardware Interface Pin List Sorted by PGA Location SysDataL28 14Hardware Interface BcDataH70 SysDataL5 16Hardware Interface Ground and Power VSS and VDD Pin List Mechanical Specifications Mechanical Specifications 18Hardware Interface 21264/EV68A Packaging21264/EV68A Packaging 21264/EV68A Bottom View Pin Up Page Cache and External Interfaces Cache and External InterfacesIntroduction to the External Interfaces Introduction to the External Interfaces 21264/EV68A System and Bcache Interfaces System Interface Physical Address Considerations Commands and AddressesPhysical Address Considerations Second-Level Cache Bcache Interface MB/WMB ECB I/O Physical Address Considerations Bcache Structure Bcache Interface SignalsBcache Structure System Duplicate Tag Stores Cache Coherency Victim Data BufferVictim Data Buffer Cache Coherency Basics Cache Block States Cache Coherency2lists the cache block states supported by the 21264/EV68A 21264/EV68A-Supported Cache Block States System Responses to 21264/EV68A Commands Mands. -4lists these commandsCache Block State Transitions Cache Block State Transitions System Responses to 21264/EV68A Commands and Reactions Using SysDc Commands 12Cache and External Interfaces Dcache States and Duplicate Tags 14Cache and External Interfaces Lock MechanismLock Mechanism Liveness and Fairness In-Order Processing of LDxL/STxC InstructionsInternal Eviction of LDxL Blocks 16Cache and External Interfaces System PortSystem Port System Port Pins System Port Pins Programming Values for System Interface Clocks Programming the System Interface ClocksProgram Values for Data-Sample/Drive CSRs 18Cache and External Interfaces Forwarded Clocks and Frame Clock Ratio 3 21264/EV68A-to-System CommandsBank Interleave on Cache Block Boundary Mode 11 Page Hit Mode of Operation Hit Mode12 21264/EV68A-to-System Command Fields Definitions 12describes the field definitions for Tables 4-10and 14describes the 21264/EV68A-to-system commands 4 21264/EV68A-to-System Commands Descriptions14 21264/EV68A-to-System Commands Descriptions 13 Maximum Physical Address for Short Bus Format 22Cache and External Interfaces 15 Programming INVALTODIRTYENABLE10 16 Programming SETDIRTYENABLE20 ProbeResponse Commands Command40 =17 21264/EV68A ProbeResponse Command 24Cache and External Interfaces 18 ProbeResponse Fields Descriptions SysAck and 21264/EV68A-to-System Commands Flow Control18describes the ProbeResponse command fields Probe Commands Four Cycles System-to-21264/EV68A Commands19 System-to-21264/EV68A Probe Commands RVB RPB 21 lists the data movement selected by Probe43 20 System-to-21264/EV68A Probe Commands Fields Descriptions22lists the next cache block state selected by Probe20 21 Data Movement Selection by Probe43 28Cache and External Interfaces Data Transfer Commands Two Cycles23 Data Transfer Command Format 24 SysDc40 Field Description 24describes the SysDc40 field 30Cache and External Interfaces Data Movement In and Out of the 21264/EV68A8.1 21264/EV68A Clock Basics Fast Data Mode 32Cache and External Interfaces 25 Sysclk Cycles Between SysAddOut and SysData Fast Data Disable Mode 26shows four example configurations and shows their use26 Cbox CSR SYSDCDELAY40 Examples SysDataInValidL and SysDataOutValidL 27 Four Timing ExamplesSysDataInValidL 34Cache and External Interfaces SysFillValidL SysDataOutValidL 36Cache and External Interfaces Data Wrapping28 Data Wrapping Rules 30 Wrap Interleave Order 30defines the interleaved scheme for the wrap order29 System Wrap and Deliver Data 31defines the wrap order for double-pumped data trans fers Nonexistent Memory Processing31 Wrap Order for Double-Pumped Data Transfers 38Cache and External Interfaces 21264/EV68A Command NXM Address System/21264/EV68A Response 40Cache and External Interfaces 10.1 21264/EV68A Commands and System ProbesOrdering of System Port Transactions System Port Bcache Port Bcache Port 35 Range of Maximum Bcache Clock Ratios Bcache Port Pins36 Bcache Port Pins 44Cache and External Interfaces Bcache Clocking Setting the Period of the Cache Clock 37 BCCPUCLKDELAY10 Values38 BCCLKDELAY10 Values 46Cache and External Interfaces 39 Program Values to Set the Cache Clock Period Single-Data Bcache Data Read and Tag Read Transactions Bcache Transactions41 Data-Sample/Drive Cbox CSRs 48Cache and External Interfaces Bcache Data Write Transactions When the ratio is odd, bcfrm is twice the ratio When the ratio is even, bcfrm is equal to the ratioFor example, in single-data mode Dual-data mode, bcfrm is twice the ratio Relationship Between Write-to-Read Bcwrrdbubbles and wrrd Pin DescriptionsRelationship Between Read-to-Write Bcrdwrbubbles and rdwr 50Cache and External Interfaces 43 Programming the Bcache Control Pins Bcache Control Pins44 lists the combination of control pin assertion for BcAddH234 46 Control Pin Assertion for Ramtype C 45 Control Pin Assertion for Ramtype B47 Control Pin Assertion for Ramtype D 52Cache and External Interfaces BcDataInClkH and BcTagInClkH Bcache BankingDisabling the Bcache for Debugging 54Cache and External Interfaces InterruptsInterrupts Internal Processor Registers Internal Processor Registers Mbox IPRs Ebox IPRs Ebox IPRsCycle Counter Register CC Cycle Counter Control Register Ccctl Virtual Address Control Register Vactl Virtual Address Register VA2describes the Ccctl register fields Cycle Counter Control Register Fields Description 3describes the virtual address control register fields Virtual Address Format Register VaformVirtual Address Control Register Fields Description VAFORM32 Ibox IPRs Ibox IPRsITB Tag Array Write Register Itbtag ITB PTE Array Write Register Itbpte ITB Invalidate Single Register Itbis ITB Invalidate All Process ASM=0 Register ItbiapITB Invalidate All Register Itbia Exception Address Register Excaddr ProfileMe PC Register Pmpc4describes the ProfileMe PC register fields ProfileMe PC Fields Description Instruction Virtual Address Format Register Ivaform Interrupt Enable and Current Processor Mode Register Iercm 10Internal Processor Registers Software Interrupt Request Register SirrIercm Register Fields Description Software Interrupt Request Register Fields Description Interrupt Summary Register Isum6describes the software interrupt request register fields 7describes the interrupt summary register fields Hardware Interrupt Clear Register HwintclrInterrupt Summary Register Fields Description 12Internal Processor Registers 8describes the hardware interrupt clear register fields Exception Summary Register ExcsumHardware Interrupt Clear Register Fields Description Mchkd W1C 14Internal Processor Registers 9describes the exception summary register fieldsException Summary Register Fields Description Ibox Control Register Ictl PAL Base Register Palbase10describes the PAL base register fields 10 PAL Base Register Fields Description 16Internal Processor Registers 11describes the Ibox control register fields11 Ibox Control Register Fields Description STWAIT64K SingleissuehPCT1EN PCT0EN 18Internal Processor Registers Ibox Status Register IstatSpce 12 Ibox Status Register Fields Description 12describes the Ibox status register fieldsMIS TRP 20Internal Processor Registers Icache Flush Register Icflush Sleep Mode Register SleepIcache Flush ASM Register Icflushasm Clear Virtual-to-Physical Map Register Clrmap 22Internal Processor Registers 14describes the process context register fields14 Process Context Register Fields Description 15 Performance Counter Control Register Fields Description Performance Counter Control Register Pctrctl15describes the performance counter control register fields Pmstalled PctxppcePmkilledbm SL0 Mbox IPRs Mbox IPRsDTB Tag Array Write Registers 0 and 1 DTBTAG0, DTBTAG1 16 Performance Counter Control Register Input Select Fields 17 DTB Alternate Processor Mode Register Fields Description DTB Alternate Processor Mode Register DtbaltmodeDTB PTE Array Write Registers 0 and 1 DTBPTE0, DTBPTE1 17describes the Dtbaltmode register fields Dstream TB Invalidate All Register Dtbia Dstream TB Invalidate All Process ASM=0 Register DtbiapDstream TB Invalidate Single Registers 0 and 1 DTBIS0,1 ALTMODE10 Memory Management Status Register Mmstat Dstream TB Address Space Number Registers 0 and 1 DTBASN0,118describes the memory management status register fields 18 Memory Management Status Register Fields Description ACV Mbox Control Register MctlFor Dcache Control Register Dcctl Erences to superpages result in access violations19describes the Mbox control register fields 19 Mbox Control Register Fields Description 20 Dcache Control Register Fields Description Dcache Status Register Dcstat20describes the Dcache control register fields Cbox CSRs and IPRs Cbox CSRs and IPRs21describes the Dcache status register fields 21 Dcache Status Register Fields Description Cbox Shift Register Cshft Cbox Data Register CdataCbox Writeonce Chain Description 22 describes the Cbox data register fields 34Internal Processor Registers 24 Cbox Writeonce Chain Order Mboxbcprbstall BCLATDATAPATTERN031 BCLATTAGPATTERN023 BCWRRDBUBBLES03 36Internal Processor Registers SYSCLKDELAY10 38Internal Processor Registers Cbox Writemany Chain Description 25 Cbox Writemany Chain Order 40Internal Processor Registers 26 Cbox Read IPR Fields Description Cbox Read Register IPR Description 0 1 1 Istreammemerr 0 1 1 Dstreammemerr Privileged Architecture Library Code Privileged Architecture Library CodePALcode Description PALmode Environment PALmode Environment Opcodes Reserved for PALcode Required PALcode Function CodesRequired PALcode Function Codes Hwld Instruction Hwst Instruction Opcodes Reserved for PALcode3describes the Hwld instruction fields Hwld Instruction Fields Descriptions Hwst Instruction Fields Descriptions Hwret Instruction4describes the Hwst instruction fields 5describes the Hwret instruction fields Hwmfpr and Hwmtpr InstructionsHwret Instruction Fields Descriptions Hint Internal Processor Register Access Mechanisms Internal Processor Register Access Mechanisms6describes the Hwmfpr and Hwmtpr instructions fields Hwmfpr and Hwmtpr Instructions Fields Descriptions Hardware Structure of Explicitly Written IPRs IPR Scoreboard Bits Paired Instruction Fetch Order IPR Access OrderingHardware Structure of Implicitly Written IPRs 10Privileged Architecture Library Code PALshadow Registers PALshadow RegistersPALcode Emulation of the Fpcr PALcode Entry Points PALcode Entry Points PALcode Exception Entry Locations PALcode Exception Entry Points Translation Buffer TB Fill Flows Translation Buffer TB Fill FlowsDTB Fill 14Privileged Architecture Library Code Wr PTE LD-PTE, write TB Wr DataTb miss 16Privileged Architecture Library Code ITB Fill Performance Counter Support Performance Counter Support Aggregate Mode Programming Guidelines General PrecautionsAggregate Mode Precautions IPRs Used for Performance Counter Support Operation 10 Aggregate Mode Returned IPR ContentsPctrctl SL0 SL1 This input counts Mbox replay traps ProfileMe Mode Programming Guidelines11shows the counter modes that are used with Aggregate mode 12 Cmov Decomposed 22Privileged Architecture Library Code 13 ProfileMe Mode Returned IPR Contents Inum retire delay cycles ProfileMe Counting Mode Description Cycle counting Counter Modes for ProfileMe Mode 14shows the counter modes that are used with ProfileMe mode14 ProfileMe Mode Pctrctl Input Select Fields 24Privileged Architecture Library Code Power-Up Reset Flow and the ResetL and Dcokh Pins Initialization and Configuration21264/EV68A Reset State Machine Major Operations Initialization and Configuration Constraints Power-Up Reset Flow and the ResetL and Dcokh Pins Signal Pin Reset State Power Sequencing and Reset State for Signal Pins Pllvdd Clock Forwarding and System Clock Ratio Configuration PLL Pin Signal Names and Initialization State BiST and Srom Load and the TestStatH Pin PLL Ramp Up EV68A Clock Forward Reset and System Interface InitializationPower-Up Flow Signals and Their Constraints Effect on IPRs After Fault Reset Fault Reset FlowFault Reset Flow Energy Star Certification and Sleep Mode Flow Energy Star Certification and Sleep Mode Flow 10Initialization and Configuration Effect on IPRs After Transition Through Sleep Mode Warm Reset Flow Warm Reset FlowSignals and Constraints for the Sleep Mode Sequence Effect on IPRs After Warm Reset 12Initialization and Configuration Initialization Mode ProcessingArray Initialization Array Initialization Evictenable BCWRTSTS30 Bcbankenable Initialization Mode Processing 10 Internal Processor Registers at Power-Up Reset State Internal Processor Register Power-Up Reset State14Initialization and Configuration External Interface Initialization Internal Processor Register Power-Up Reset State Reset State Machine Ieee 1149.1 Test Port ResetIeee 1149.1 Test Port Reset 16Initialization and Configuration 11 21264/EV68A Reset State Machine State Descriptions Reset State Machine 18Initialization and Configuration Phase-Lock Loop PLL Functional Description Phase-Lock Loop PLL Functional DescriptionDifferential Reference Clocks PLL Output Clocks 20Initialization and Configuration Power-Up/Reset Clocking Error Detection and Error Handling Error Detection and Error Handling21264/EV68A Error Detection Mechanisms Icache Data or Tag Parity Error Data Error Correction CodeDcache Tag Parity Error Data Error Correction Code Load Instruction Dcache Data Single-Bit Correctable ECC ErrorDcache Data Single-Bit Correctable ECC Error Dcache Duplicate Tag Parity Error Dcache Store Second ErrorDcache Store Second Error Store Instruction Quadword or Smaller Bcache Data Single-Bit Correctable ECC Error Bcache Tag Parity ErrorBcache Tag Parity Error Controlling Bcache Block Parity Calculation Dcache Fill from Bcache Bcache Data Single-Bit Correctable ECC Error Memory/System Port Single-Bit Data Correctable ECC Error Memory/System Port Single-Bit Data Correctable ECC ErrorBcache Victim Read Icache Fill from Memory Dcache Fill from Memory Bcache Data Single-Bit Correctable ECC Error on a Probe Bcache Data Single-Bit Correctable ECC Error on a ProbeDouble-Bit Fill Errors Error Case Summary Error Case Summary3summarizes the various error cases and their ramifications Section D.36 Cstatdstreammemerr Mchk CstatistreammemerrCRD Cstatprobebcerr Mchk CstatistreambcdblPage Electrical Data Electrical Characteristics1lists the maximum electrical ratings for the 21264/EV68A Maximum Electrical Ratings DC Characteristics DC CharacteristicsSignal Types Idcpower Input DC Reference Pin Idcref VDD IdcpowerInput Differential Amplifier Receiver IDA Input Differential Amplifier Clock Receiver Idaclk Pin Type Open-Drain Output Driver OOD Pin Type Open-Drain Driver for Test Pins OodtpIOZ Codtp 12 Push-Pull Output Clock Driver Oppclk 11 Push-Pull Output Driver OPP AC Test Conditions AC CharacteristicsAC Characteristics TSU1 TDH2 13 AC Specifications Dcokh AC Characteristics Page Operating Temperature at Heat Sink Center Tc Operating TemperatureThermal Management That causes thermal failure 10-2Thermal Management Operating TemperatureΘca at Various Airflows for 21264/EV68A Heat Sink Specifications Heat Sink Specifications 10-4Thermal Management Type 2 Heat Sink Type 3 Heat Sink 10-6Thermal Management Thermal Design ConsiderationsThermal Design Considerations Test Pins Testability and DiagnosticsDedicated Test Port Pins Testability and Diagnostics SROM/Serial Diagnostic Terminal Port SROM/Serial Diagnostic Terminal Port11-2Testability and Diagnostics Srom Load Operation Ieee 1149.1 Instructions and Opcodes Ieee 1149.1 PortIeee 1149.1 Port TestStatH Pin 11-4Testability and DiagnosticsTestStatH Pin TAP Controller State Machine Power-Up Self-Test and Initialization Power-Up Self-Test and InitializationBuilt-in Self-Test Srom Initialization Serial Instruction Cache Load Operation 11-6Testability and Diagnostics References See Appendix B for a listing of the Boundary-Scan RegisterIcache Bit Fields in an Srom Line Page Alpha Instruction Summary Alpha Instruction SetTable A-1 Instruction Format and Opcode Notation Alpha Instruction Set A-1 Alpha Instruction Summary Pcd Trap to PALcode Mbr Branch to subroutineOpr 11.24 Cmove if = zero Opr 11.46 Cmove if ≥ zero 17.010 Convert longword to quadword 15.0AF Convert Gfloating to quadword15.0BC Convert quadword to Ffloating 15.0BE Convert quadword to Gfloating 17.02E Fcmove if ≤ zero 17.02F Fcmove if zero17.02C Fcmove if zero 17.02B Fcmove if ≠ zero Opr 13.60 Multiply quadword with integer overflow enable Opr 13.40 Multiply longword with integer overflow enableOpr 1C.31 Pixel error Mem Load Sfloating Mbr 1A.2 Return from subroutine Opr 1C.36 Pack words to bytes Mfc 18.E000 Read and clearMfc 18.C000 Read process cycle counter 18.F000 Read and set Opr 10.02 Scaled add longword by Opcodes Reserved for Compaq Reserved OpcodesReserved Opcodes Opcodes Reserved for PALcode Ieee Floating-Point InstructionsIeee Floating-Point Instructions 18B 10B 14B 08B 00B 04B02B 06B 12B 16B VAX Floating-Point Instructions VAX Floating-Point InstructionsIndependent Floating-Point Instructions Opcode Summary Opcode Summary Mem Res Mem Table A-9explains the symbols used in Table A-8Ieee floating-point instruction opcodes Floating-point operate instruction opcodes 14Alpha Instruction Set Ieee Floating-Point ConformanceIeee Floating-Point Conformance Alpha Instruction Set A-15 Table A-11 Exceptional Input and Output Conditions 16Alpha Instruction Set Alpha Instruction Set A-17 Cmpteq Cmptun InputCmptlt Cmptle Input Fbeq Fbne Fblt Fble Fbgt Fbge LDS LDT STS STT Cpys Cpysn Boundary-Scan Register 21264/EV68A Boundary-Scan Register Pllvdd Boundary-Scan Register 21264/EV68A Boundary-Scan Register B-3 421264/EV68A Boundary-Scan Register 21264/EV68A Boundary-Scan Register B-5 621264/EV68A Boundary-Scan Register 21264/EV68A Boundary-Scan Register B-7 821264/EV68A Boundary-Scan Register 21264/EV68A Boundary-Scan Register B-9 1021264/EV68A Boundary-Scan Register 21264/EV68A Boundary-Scan Register B-11 1221264/EV68A Boundary-Scan Register Serial Icache Load Predecode Values C-1 Serial Icache Load Predecode ValuesPage PALcode Restrictions and Guidelines D-1 PALcode Restrictions and Guidelines 2PALcode Restrictions and Guidelines PALcode Restrictions and Guidelines D-3 4PALcode Restrictions and Guidelines Initwritemany PALcode Restrictions and Guidelines D-5 6PALcode Restrictions and Guidelines PALcode Restrictions and Guidelines D-7 8PALcode Restrictions and Guidelines PALcode Restrictions and Guidelines D-9 Restriction 7 Replay Trap, Interrupt Code Sequence, and STF Restriction 9 PALmode Istream Address Ranges Restriction 10 Duplicate IPR Mode BitsRestriction 9 PALmode Istream Address Ranges 10PALcode Restrictions and Guidelines Restriction 11 Ibox IPR Update Synchronization Restriction 11 Ibox IPR Update SynchronizationRestriction 13 DTB Fill Flow Collision Restriction 14 Hwret Guideline 16 JSR-BAD VA Guideline 20 Ictlsbe Stream Buffer EnableRestriction 21 HWRET/STALL After Hwmtpr ASN0/ASN1 Guideline 16 JSR-BAD VA PALcode Restrictions and Guidelines D-13 Restriction 22 HWRET/STALL After Hwmtpr IS0/IS1Restriction 22 HWRET/STALL After Hwmtpr IS0/IS1 Guideline 26 Conditional Branches in PALcode Restriction 25 Hwmtpr Itbia After ResetRestriction 24 HWRET/STALL After Hwmtpr ICFLUSH, Icflushasm 14PALcode Restrictions and Guidelines PALcode Restrictions and Guidelines D-15 Guideline 29 JSR, JMP, RET, and Jsrcor in PALcodeRestriction 30 Hwmtpr and Hwmfpr to the Cbox CSR 16PALcode Restrictions and Guidelines Restriction 30 Hwmtpr and Hwmfpr to the Cbox CSR Restriction 32 Pctrctl Update Restriction 31 ICTLVA48 UpdateRestriction 31 ICTLVA48 Update PALcode Restrictions and Guidelines D-17 Restriction 33 Hwld Physical/Lock Use Guideline 35 Hwintclr UpdateRestriction 36 Updating Ictlsde Restriction 37 Updating VACTLVA48 PALcode Restrictions and Guidelines D-19 Restriction 40 Scrubbing a Single-Bit Error 20PALcode Restrictions and Guidelines Restriction 40 Scrubbing a Single-Bit Error PALcode Restrictions and Guidelines D-21 Restriction 42 Updating VACTL, CCCTL, or CC IPRsRestriction 43 No Trappable Instructions Along with 22PALcode Restrictions and Guidelines Restriction 47 Cache Eviction for Single-Bit Cache Errors PALcode Restrictions and Guidelines D-23 Restriction 47 Cache Eviction for Single-Bit Cache Errors 24PALcode Restrictions and Guidelines Table E-1 Bcache Forwarding Clock Pin Groupings 21264/EV68A-to-Bcache Pin InterfaceForwarding Clock Pin Groupings Late-Write Non-Bursting SSRAMs Late-Write Non-Bursting SSRAMsData Pin Usage Tag Pin Usage Table E-4 Dual-Data Rate Ssram Data Pin Usage Dual-Data Rate SSRAMsDual-Data Rate SSRAMs 421264/EV68A-to-Bcache Pin Interface TrstlTable E-5 Dual-Data Rate Ssram Tag Pin Usage 21264/EV68A-to-Bcache Pin Interface E-5 Page Glossary BIU BSR Cisc CPI CmosCPU CSR Dram DMADTB DTL FET FepromFEU Fpga IDU Gclk Ipga IowbITB Jfet MBO MAFMBZ Mips Naturally Aligned MSINmos Nvram PGA PALPLA Plcc Prom PqfpRAM RAS ROM RiscRTL SAM Simm SdramSIP Sipp TTL StramUart Unaligned Uvprom UnpredictableVAF VDF Writeblock WAR Numerics Index Index-2 Index-3 Index-4 ECC Index-6 Index-7 Index-8 Index-9 Index-10 Index-11 Index-12