Sun Microsystems’ UltraSPARC-IIi a Stunt-Free Presentation

1. Sun Microsystems’UltraSPARC-IIia Stunt-Free Presentation by Christine Munson Amanda Peters Carl Sadler

2. Overview • Scalable Processor ARChitecture • allows “scalable” range of price and performance options • different numbers of CPU registers can be implemented • RISC Processor • Introduced in 1987 • Now primarily used by multiple-processor Unix workstations

3. Specifications • 64-bit memory addresses • 64-bit integer operations • 4-way SuperScalar design • Available in speeds of 270, 300, 333 or 360 MHz • Nine-stage processor pipeline • VIS instruction set for multimedia performance

4. Basic Architecture • Integer Unit (IU) • basic processing and integer arithmetic • Floating Point Unit (FPU) • floating-point arithmetic • processes concurrently with IU • PCI Bus Module (PBM) • provides a direct interface between the CPU and PCI bus, maximizing data transfer efficiency

5. Other Units • Load/Store Buffer Units (LSU) • handles loads and stores • Graphics Unit (GRU) • utilizes VIS graphics instructions for high-performance multimedia processing • Prefetch and Dispatch Unit (PDU) • manages instructions to minimize execution units’ downtime

6. Block Diagram - Typical Setup

7. IU Control/Status Registers • Program Counter (PC) • contains address of current instruction • Next PC (nPC) • contains address of next instruction • Processor State Register (PSR) • processor status • condition code flags • five-bit Current Window Pointer (CWP)

8. IU Control/Status Registers Cont’d • Window Invalid Mask (WIM) • 32-bits, representing windows • bit values represent invalid windows • Trap Base Register (TBR) • points to trap handler • contains trap type code • Y Register • allows creation of 64-bit products

9. General-Purpose Registers • 8 Window Registers, 8 Global Registers • Window Registers overlap in circular fashion • Overflows and underflows are trapped by WIM so that they can be accommodated by software

10. Circular 8-Window Implementation

11. Instruction Set • ~140 Standard SPARC-V9 Instructions • Six categories: • Load/Store • Arithmetic/Logical/Shift • Control Transfer • Read/Write Control Registers • Floating Point • Coprocessor

12. Instruction Formats • 32-bit instructions • Bits 30 and 31 specify format • Immediate/Implied Addressing

13. Memory • 64-bit addresses • Upper 32 bits can be masked with zero for backwards compatibility • Location expressed by typical register offset scheme

14. Memory Controller Unit (MCU) • Controls all memory accesses • External transceivers allow DRAM data to be double the width of the processor’s memory pins: • Processor: 72 bits • 64 bits + 8-bits for Error Control Code • With MCU: 144 bits • 128 bits + 16-bit ECC • Significant to both performance and compatibility

15. Typical Memory Configuration

16. Processor Pipeline • Most instructions occur over nine stages • Instructions are considered terminated after the last stage (write)

17. Pipeline Stages • Stage 1: Fetch Stage (F) • up to four instructions retrieved from Instruction Cache • Stage 2: Decode Stage (D) • instructions are pre-decoded and sent to the Instruction Buffer • Stage 3: Group Stage (G) • up to four instructions are received from the PDU • instructions are grouped, weighted, and dispatched to the appropriate units

18. Pipeline Stages Continued • Stage 4: Execution Stage (E) • instructions are executed and a virtual memory address of the instruction is calculated • Stage 5: Cache Access Stage (C) • the virtual memory address is verified and converted to a physical address • Stage 6: N1 Stage • cache misses are handled • physical address is sent to the Store Buffer

19. Pipeline Stages Continued • Stage 7: N2 Stage • most floating-point instructions complete at this stage • Stage 8: N3 Stage • traps are resolved • Stage 9: Write Stage (W) • final results written to register files • instruction is considered terminated

20. VIS Instruction Set • Specialized extension to the standard SPARC instruction set • ~50 instructions • Utilizes a Graphics Status Register (GSR) • Provides high-performance graphics data manipulation • Allows variable partitioning of 64-bit registers for numerical processing, reminiscent of saturation arithmetic

21. VIS Data Formats • Standard partitioning formats accommodate common graphics representations

22. VIS Instruction Format • Standard instruction format accommodates implementation-specific opcodes

23. Role in the Marketplace • Scalable architecture makes SPARC family highly marketable • Open Architecture - manufacturers can buy licenses to produce SPARC-compliant systems • Increasing speed • 1.5 GHz by 2002 • Overall, high-performance modules, single-chip solution

24. End