The Design of a Microprocessor

This text has been produced for the benefit of students in computer and infor­ mation science and for experts involved in the design of microprocessors. It deals with the design of complex VLSI chips, specifically of microprocessor chip sets. The aim is on the one hand to provide an overview of the state of the art, and on the other hand to describe specific design know-how. The depth of detail presented goes considerably beyond the level of information usually found in computer science text books. The rapidly developing discipline of designing complex VLSI chips, especially microprocessors, requires a significant extension of the state of the art. We are observing the genesis of a new engineering discipline, the design and realization of very complex logical structures, and we are obviously only at the beginning. This discipline is still young and immature, alternate concepts are still evolving, and "the best way to do it" is still being explored. Therefore it is not yet possible to describe the different methods in use and to evaluate them. However, the economic impact is significant today, and the heavy investment that companies in the USA, the Far East, and in Europe, are making in gener­ ating VLSI design competence is a testimony to the importance this field is expected to have in the future. Staying competitive requires mastering and extending this competence.

1. Introduction.- 1. Introduction.- 1.1. Overview.- 1.2. Structure of the Book.- 1.3. S/370 Architecture.- 1.4. Layered Processor Structure.- 2. Logic Design.- 2.1. Design Overview.- 2.1.1 Introduction.- 2.1.1.1 Design Goals.- 2.1.1.2 Processor Structure.- 2.1.2 Chip Set Description.- 2.1.2.1 Processing Unit (CPU) Chip.- 2.1.2.2 Memory Management Unit (MMU) Chip.- 2.1.2.3 Storage Controller (STC) Chip.- 2.1.2.4 Clock Chip.- 2.1.2.5 Control Store (CS) Chip.- 2.1.2.6 Floating Point Unit (FPU) Chip.- 2.1.3 Chip Interconnection Busses.- 2.1.4 Cache Timing Considerations.- 2.1.5 Miscellaneous.- 2.1.5.1 Reliability, Availability, Serviceability (RAS).- 2.1.5.2 System Measurement Interface (SMI).- 2.1.5.3 Other Processor Components.- 2.2. Processing Unit Chip.- 2.2.1 Design Considerations.- 2.2.2 Block Diagram Description.- 2.2.3 Modes of Operation.- 2.2.3.1 S/370 Mode.- 2.2.3.2 Micromode.- 2.2.3.3 Forced Operations.- 2.2.4 Pipelining.- 2.2.5 Data Local Store Layout.- 2.2.6 Micro Instructions.- 2.2.6.1 Data Local Store Addressing.- 2.2.6.2 Microinstructions Types and Formats.- 2.2.6.3 Reducing the Number of Branch Microinstructions.- 2.2.7 Data Flow Logic.- 2.2.7.1 ALU, Shift, Units and DLS.- 2.2.7.2 Bus Unit and Processor Bus Operations.- 2.2.8 Prefetch Buffer.- 2.2.9 Floating-Point Coprocessor Interface.- 2.3 Timer Support.- 2.3.1 Introduction to the Timer Functions.- 2.3.2 Format of the Timer Binary Counters.- 2.3.3 Functional Description and Block Diagram.- 2.3.4 Communication with the CPU.- 2.3.5 Programmable Clock Cycle Time.- 2.4. Memory Management Unit Chip.- 2.4.1 Overview.- 2.4.2 Storage Hierarchy Elements.- 2.4.2.1 Virtual Storage Addressing.- 2.4.2.2 Translation-Lookaside Buffer.- 2.4.2.3 Cache Operation.- 2.4.2.4 Key Store.- 2.4.2.5 Combined Operation.- 2.4.3 MMU Chip Data Flow.- 2.4.4 Array Macros.- 2.4.4.1 Translation-Lookaside Buffer (TLB).- 2.4.4.2 Cache Directory.- 2.4.4.3 Cache Array.- 2.4.4.4 Keystore.- 2.4.5 Storage Controller Interface.- 2.5. Storage Controller Chip.- 2.5.1 STC Chip Structure.- 2.5.1.1 Memory Control Unit.- 2.5.1.2 Error Correction Unit.- 2.5.1.3 STC Chip Interfaces.- 2.5.2 Memory Organization and Control.- 2.5.2.1 Overview.- 2.52.2 Memory Card.- 2.5.2.3 Memory Performance.- 2.5.2.4 Fetch Operation.- 2.5.2.5 Store Operation.- 2.5.3 Data Integrity.- 2.5.3.1 Refresh.- 2.5.3.2 ECC (Error Correction Codes).- 2.5.3.3 Complement Retry.- 2.5.3.4 Redundant Bit.- 2.5.3.5 Scrub.- 2.5.3.6 Address Fault Protection.- 2.5.4 Diagnostics.- 2.5.5 Personalization.- 2.6. Floating Point Coprocessor.- 2.6.1 General Description.- 2.6.2 Floating-Point Instructions and Data Format.- 2.6.3 FPU Interface and Communication.- 2.6.4 Chip Logical Description.- 2.6.4.1 Overview.- 2.6.4.2 Exponent Dataflow.- 2.6.4.3 Mantissa Dataflow.- 2.6.5 Reliability, Checking and Testing.- 2.6.5.1 Reliability.- 2.6.5.2 Checking.- 2.6.6 Performance.- 2.7. Bus Interface Chips.- 2.7.1 Overview.- 2.7.2 MBA Chip.- 2.7.3 BCU Chip.- 2.8. Clock Chip.- 2.8.1 Central Clock Generation Versus Distributed Clock Generation.- 2.8.2 Logical Implementation.- 2.8.3 Timing Tolerances, Reset and Checking.- 2.9. Clocking.- 2.9.1 Clock Signal Types.- 2.9.2 Clock Generation Flow.- 2.9.3 Clock Pulse Generation.- 2.9.4 Evaluation of the Clock Skews.- 2.9.5 Logic Chip Clock Distribution.- 2.9.5.1 Standàrd On-Chip Clock Distribution.- 2.9.5.2 High Performance On-Chip Clock Distribution.- 2.9.6 Evaluation of the Clocking Scheme.- 2.9.7 Clock Variation.- 2.10. Processor Bus.- 2.10.1 Processor Bus Connections.- 2.10.2 Processor Bus Implementation.- 2.10.3 Processor Bus Operation Example.- 2.11. Reliability, Availability, Serviceability.- 2.11.1 Overview.- 2.11.2 RAS Strategy and Requirements.- 2.11.3 Initial Chip Set Start and Loading.- 2.11.4 Error Detection.- 2.11.5 Machine Check Handling.- 2.11.6 Support Interface.- 2.11.6.1 Unit Support Interface Description.- 2.11.6.2 Unit Support Interface Operation.- 3. Logic Design Tools.- 3.1. Logic Design System Overview.- 3.2. Hardware Design Language.- 3.2.1 Overview.- 3.2.2 The Design Level.- 3.2.3 Design Rules Checks.- 3.2.4 The Macro Level.- 3.2.5 The System Level.- 3.2.6 Design System Dataflow.- 3.2.7 Overall Comparison with VHDL.- 3.3. Logic Synthesis.- 3.3.1 Overview.- 3.3.2 Logic Synthesis Methodology.- 3.3.3 LSS Overview.- 3.3.4 Technology Information.- 3.3.5 Partitioned Synthesis.- 3.3.6 Synthesis Experience.- 3.4 Logic Synthesis Design Experience.- 3.4.1 Overview.- 3.4.2 The Design System.- 3.4.3 Challenges in Using LSS.- 3.4.4 Delay Optimization and the Use of LSS.- 3.4.5 Results and Designers’ Echo.- 3.4.6 Discussion.- 3.4.7 Conclusions.- 3.5. Timing Analysis and Verification.- 3.5.1 Overview.- 3.5.2 Delay Equations.- 3.5.3 Capacitance Estimate.- 3.5.4 Multiple Clock Designs.- 3.5.5 Multiple Cycle Paths.- 3.5.6 Global Timing Correction for Logic Synthesis.- 3.6. Logic Design Verification.- 3.6.1 Overview.- 3.6.2 The Concept of Using Logic Simulation.- 3.6.3 Modelling Requirements.- 3.6.4 The Phases in Logic Design Verification.- 3.6.5 What Drives the Simulation — Testcases.- 3.6.6 The Testcase Execution Control Program.- 3.7. Logic Simulation.- 3.7.1 Overview.- 3.7.2 Hardware Specification Languages.- 3.7.3 Compilation Techniques.- 3.7.4 Simulation Control.- 3.7.5 Distributed Simulation.- 4. CWp Technology.- 4.1 Chip Technology Overview.- 4.1.1 Technology.- 4.1.2 Circuit Libary and Chip Image.- 4.2. Master Image Chip.- 4.3. VLSI Book Library and Array Macros.- 4.3.1 Cell Design.- 4.3.2 Circuit Library.- 4.3.3 Sub-Circuit Elements.- 4.3.4 Macro Design.- 4.4. A New I/O Driver Circuit.- 4.4.1 Problem Definition.- 4.4.2 Driver Family.- 4.4.3 Dynamic Control.- 4.5. Embedded Array Macros.- 4.5.1 Array Configurations.- 4.5.2 Storage Cell and Circuit Design.- 4.5.3 Array Integration.- 4.5.4 Testing of Embedded Arrays.- 4.6. Packaging.- 4.6.1 Overview.- 4.6.2 First Level Packaging.- 4.6.3 Electrical Considerations.- 4.6.4 Second Level Package.- 5. Semiconductor Technology.- 5.1. Design for Testability.- 5.1.1 Overview.- 5.1.2 Failure Types and Failure Models.- 5.1.3 Structural Test.- 5.1.4 Design for Testability.- 5.1.5 LSSD (Level Sensitive Scan Design).- 5.1.5.1 Overview.- 5.1.5.1 LSSD Rules and Partitioning.- 5.1.6 Additional Test Features.- 5.1.6.1. Internal Tristate Driver.- 5.1.6.2 Observation Points.- 5.1.6.3 Logic Circuit Layout Optimized for Defect Sensitivities.- 5.1.7 Random Pattern Testing.- 5.1.8 Auto Diagnostic.- 5.2. Test and Characterization.- 5.2.1 Wafer and Module Test.- 5.2.1.1 Test Overview.- 5.2.1.2 Process Parameter Test.- 5.2.1.3 Logic Test on Wafer and Module.- 5.2.1.4 Functional Pattern Test.- 5.2.1.5 Logic Test Equipment.- 5.2.2 Failure Localization and Characterization.- 5.2.2.1 Second Metal Test.- 5.2.2.2 Internal Probing Station.- 5.2.2.3 Fail Locating by Internal Probing.- 5.2.2.4 Performance Verification.- 5.3. Semiconductor Process / Device Design.- 5.3.1 The Semiconductor Process.- 5.3.2 Layout Rules.- 5.3.3 Electrical Device Properties.- 5.4. Failure Analysis.- 5.4.1 Purpose of Failure Analysis.- 5.4.2 Failure Analysis Strategy and Methods.- 5.4.3 Failure Analysis Examples.- 5.4.3.1 Particles.- 5.4.3.2 Metal Interruptions at Steep Steps.- 5.4.3.3 Oxide Residues in Contact Holes.- 5.4.3.4 Leakage between Vdd and Ground.- 5.4.3.5 Signal to Ground Leakage.- 5.4.3.6 Source-Drain Leakage.- 5.4.3.7 Latch-Up.- 6. Physical Design Tools.- 6.1 Physical Design Concept.- 6.2 Hierarchical Physical Design.- 6.2.1 Methodology.- 6.2.2 Partitioning and Floorplanning.- 6.2.3 Implantation.- 6.2.4 Detailed Processing.- 6.2.5 Chip Assembly.- 6.3 Hierarchical Layout and Checking.- 6.3.1 Chip Layout.- 6.3.2 Chip Merge and Final Data Generation.- 6.3.3 Checking.- 6.4. Delay Calculator and Timing Analysis.- 6.4.1 Circuit Delay.- 6.4.2 Calculation Method and Simulation.- 6.4.3 Fitting Method (Least Square Fit).- 6.5. Physical Design Experience.- 6.5.1 Master Image Development.- 6.5.2 Physical Design.- 6.5.3 Hardware Bring-Up.- 6.5.4 Lessons Learned.- 7. System Implementation.- 7.1. ES/9370 System Overview.- 7.2. High Level Microprogramming in 1370.- 7.2.1 Overview.- 7.2.2 Concepts and Facilities.- 7.2.2.1 Processor Structure.- 7.2.2.2 Instruction Interpretation.- 7.2.2.3 Control Spaces and Associated Instructions.- 7.2.2.4 Mode Control and Associated Instructions.- 7.2.3 ES/9370 Realization.- 7.2.3.1 ES/9370 System Structure.- 7.2.3.2 Service Processor to I/O Controller Communication.- 7.2.3.3 Extending the Kernel Functions.- 7.2.3.4 Simulation Concept for I370 Programs.- 7.2.4 Conclusions and Outlook.- 7.3. System Bring-Up and Test.- 7.3.1 Overview.- 7.3.2 Bring-Up Strategy.- 7.3.3 Basic Bring-Up Process.- 7.3.3.1 Sub-Architectural Verification.- 7.3.3.2 Architecture Verification.- 7.3.3.3 Testing Under the PAS Control Program.- 7.3.3.4 System I/O and Interaction Testing.- 7.3.4 System Bring-Up.- 7.3.5 Regression Testing.- 7.3.6 Bring-Up Results and Error Corrections.- 7.3.6.1 Basic Bring-Up.- 7.3.6.2 System Bring-Up.- 7.3.7 Summary and Conclusions.- 7.4. Outlook.- Authors.- References.