The Variety of the PowerPC Implementations

1. The Variety of the PowerPC Implementations MinHo Son Microprocessors, V22-480-002 Professor Robert Dewar 5/20/2002

2. Summary • The PowerPC architecture, a RISC architecture that is developed by the alliance of IBM, Motorola, and Apple, is a flexible architecture that results in the variety of processor implementations. Motorola and IBM produce and supply the main processors of all Apple computers, mostly desktops and a few servers. Motorola also has the PowerPC processors for embedded applications. IBM produces the PowerPC embedded processors, uses its PowerPC processors in some of Unix servers, have the PowerPC compatible layer included in the POWER processors and there are other licensees of the PowerPC architecture like Xilinx and ST Mictoelectronics focusing on the embedded applications. This document summarizes these uses.

3. Topics • The aspects of the design that allows the wide variety in implementations • The embedded applications • The personal computers (Apple Macintosh) • The server applications (IBM UNIX server, Apple Xserve)

4. The aspects of the design that allow the wide variety in implementations • Minimal silicon requirement • Multilayered architectural definition • Scalable design • Controllable functionality/performance/price/power requirement/operation temperature, thus wide variety

5. The design aspects1/3 • Minimal silicon requirement • Less complex than x86, smaller transistor count, smaller die size • Gives more room to integrate more devices required for various embedded applications • IBM 4xx System-on-Chip Processors • Integrate memory controller, Ethernet interface, PCI interface • IBM Digital Set-Top Box PowerPC Integrated Controller • Integrates A/V decoders, transport demultiplexers, memory controller, peripheral interfaces • Motorola MPC8xx Integrated Communications Processors • Integrate CPM (Communication Processor Modules) that provides various communication port controllers

6. The design aspects2/3 • Multilayered architectural definition The layered approach of the PowerPC architecture provides code compatibility across implementations while allowing each implementation to choose the level of complexity for its usage (Marsala). • the defined layers (Marsala) • Book 1: User Instruction Set Architecture – “the common, base set of instructions and registers.” • Book 2: Virtual Environment Architecture – “defines additional user level functionality that is outside normal application software requirements” • Book 3: Operating Environment Architecture – “[the definition of privileged operations] required by an operation system” • Book E: “[The enhanced definition of the architecture] to expand the use of the processor in embedded applications” (IBM, “IBM and Motorola define new PowerPC …”)

7. The design aspects3/3 • Scalable design • RISC • Superscalar architecture – multiple units, multiple pipelines, out of order dispatch and execution • “Because the RISC architecture of the PowerPC is scalable, it emerges as a possible leader, not only in the entry-level market, but in the high-end computing arena.” (Chakravarty & Cannon)

8. The embedded applications • The area that the PowerPC naturally fits • Book E – a new extension in definition for embedded applications • CodePack – address the code density issue • Integration of functions • Customized Linux for the embedded applications • Usage - Network, storage, information appliances, printer, home entertainment

9. The Embedded Applications: Book E • “[The enhanced definition of the architecture] to expand the use of the processor in embedded applications” (IBM, “IBM and Motorola define new PowerPC …”) • Changes made • Endian neutral – “fully supports both accessing method” (Marsala) • “Defines a third class of registers, called device control registers (DCRs), to address peripheral registers outside of the processor core in an embedded implementation” in addition to special purpose registers and general purpose registers (Marsala) • Programmable page size (Marsala) • Two-level interrupt hierarchy, critical/non-critical (Marsala) • Additional timers in addition to the timebase (Marsala) • A 32-bit programmable decrementer • A fixed-interval timer • A watchdog timer for system hang conditions

10. The Embedded Applications:CodePack – Code Compression (IBM) • To overcome the longer code due to RISC’s 32-bit fixed length instructions • Reduces the cost of memory in the embedded systems • Two-part, hardware/software solution • The code decompressing unit placed between memory controller and the processor core in the PowerPC System-on-Chip processors • Software part to compress the code

11. The Embedded Applications:integration of functions • IBM PowerPC System-on-Chip processors • Integrated memory management units, on-chip peripheral bus, I2O messaging units (IBM) • “We are integrating advanced encryption and voice recognition functions that are normally handled less efficiently in software. In other words, IBM is taking voice and encryption technologies out of software and putting those functions in hardware for greater functionality and power efficiency” (Wilson)

12. The Embbed Aplications: Examples 1/4 • Network/Storage • IBM PowerPC 4xx System-on-Chip Processors, PowerNP NPe405 Network Processors, PowerPC 7xx Control Plane Processors • Network • Hubs/routers/switches, home gateways, cable/DSL modems, Cellular base stations • Storage • Host Bus Adapters, RAID controllers, Storage appliance • Storage Network • Storage Area Network, Network Attached Storage

13. The Embbed Aplications: Examples 2/4 • Set-Top Box • IBM STB130x0A/V Transport/Decoder • Personal Video Recorders (PVRs) • Tivo • MPEG-II compression • The PowerPC running Linux • Printers • Kyocera • Ranging from personal printers to a networked high-end color printer that uses 400 Mhz, IBM PowerPC 750CX (IBM) • Oki Data

14. The Embbed Aplications: Examples 3/4 • The low power embedded processor • IBM PowerPC 405LP • “Ultra-low power for mobile phones, PDAs, and handheld computers” (IBM) • “includes special circuitry that shuts off portions of the chip when not in use, a technique that reduces both active and standby power in chips by up to 10 times over current designs” (Wilson) • Voltage scaling, frequency scaling, flexible clock distribution, clock gating, clock freezing, hibernation, voltage reduction (IBM)

15. The Embbed Aplications: Examples 4/4 • The customized PowerPC processors • Game Console - Nintendo GameCube • Gekko – customized IBM PowerPC 405 • 32-bit integer, 64-bit floating point, 0.18 micron copper wire technology • “[Nintendo helps developers to focus] on creating [interesting] video games” by “creating the developer-friendly machine” based on well-known technology rather than the highest performing machine (Nintendo, TechTV Extended Play Staff) • Intelligent Electrical Appliances from Sanyo • Screen Phone, Web Terminal

16. The Personal Computers • Used in Apple Macintosh since 1994 • Power Mac clones for a brief period of time in mid 90’s • PowerPC 601, 602, 603, 604, 7xx (G3), MPC74xx (G4) • The RISC nature of the PowerPC helped Apple to make transition from the 68k to the PowerPC by providing good emulation performance. • OS - Apple Classic OS, Apple OS X, and PPC Linux • Holds the advantage in the multimedia content creator market • Better Photoshop performance • Availability of the high quality applications for Musicians • Mark of the Unicorn – Digital Performer • Digidesign - Protools • The AltiVec expansion (The Velocity Engine) • “Motorola's High-Performance Vector Parallel Processing Expansion to Microprocessors that implement the PowerPC Architecture”

17. The Personal Computers:AltiVec • “The vector parallel processing expansion to the PowerPC architecture” for multimedia performance (AltiVec.org) • 32, 128-bit registers separate from existing fixed, and floating point registers and 162 new instructions • Example: AltiVerb by Audio Ease • A audio signal processing software runs on Macintosh • Feeds the testing tones to the sources, either physical rooms like concert halls, or other audio processors like metal-plate reverb generators or spring reverb generators and samples the output. Then transforms any audio input using the sampled transformation, thus simulates the rooms or the other processing devices in real time or non-real time. • Currently the only software based audio signal processor that gives authentic artificial simulation comparable to the hardware audio processors that employ a large amount of DSP chips like Sony DRE-S777 – The quality gap between AltiVerb and other software audio processors that don’t utilize AltiVec may indicate the AltiVec brings the power of customized DSP chips to the general purpose PowerPC as Motorola claims.

18. The drawback of using PowerPC in personal computers • The difference from the x86 that is mostly used in personal computers may explain the processor supply shortage and the lower clock than the x86 processors that Apple suffers • The PowerPC is highly successful in the embedded applications • The much larger number of processors are used in the embedded systems than personal computers • Motorola and IBM don’t have to concentrate on the processors for personal computers • The suppliers of the PowerPC processors are not competing directly with each other • IBM and Motorola: not like Intel and AMD • IBM not designing the compatible processors with the AltiVec technology by Motorola unlike AMD that licensed the SIMD technology from Intel (MMX, SSE, SSE2) • Two different roadmaps - IBM upping the clock of G3 (PowerPC 7xx), Motorola adding expansion to G3 making G4, G5, G6 (MPC74xx/85xx/86xx) (IBM, Motorola)

19. The Server Applications • The POWER architecture • Performance Optimization With Enhanced RISC • The root of the PowerPC (Chakravarty & Cannon, 5) • POWER3 is based on the PowerPC • POWER4 includes the PowerPC layer • Used in IBM mainframes, and servers • IBM RS/6000 • Entry level UNIX server • PowerPC 604e or POWER3-II • Apple Xserve • 1-U rack-optimized design, Mac OS X server, half a terabyte storage, supporting Mac, Windows, Unix, Linux clients, no per-user license fee • Dual G4 processors

20. Reference • IBM Microelectronics: • “PowerPC Networking and Storage Markets” • “Digital Set-Top Box IBM PowerPC Processors” • “IBM and Motorola Define New PowerPC Architecture for Embedded Applications” • “CodePack: Code Compression for PowerPC Processors,” Version 1.0 • “405LP Microprocessor Forum Presentation” • “PowerPC Strategic Roadmap” • “Low Power SOC for IBM’s PowerPC Information Appliance Platform” • “PowerPC Technical Library” • IBM, “IBM Unix Servers: Entry servers” • Smith, Tanya, “PowerPC Processing at Work: Powering Up Your Printer Kyocera Corporation,” IBM PowerPC processor news, February 2001 • Marsala, Anthony, “The PowerPC Architecture: A Programmer’s View Part I & II,” IBM PowerPC processor news, April 2001 & June 2001 • Chakravarty, Dipto & Casey, Cannon, “PowerPC: Concepts, Architecture, and Design,” McGraw-Hill, Inc., New York, 1994 • Motorola: • “MPC82XX and MPC8XX Integrated Communications Processors” • “AltiVec” • “PowerPC Roadmap” • Nintendo, “Nintendo GameCube” • TechTV, Extended Play Staff, “Nintendo GameCube Specs” • AltiVec.org, “AltiVec – vector, FFT, DSP, fast fourier transform, digital signal processing” • Audio Ease, “What is AltiVerb?” • Sony, “Shape Your Acoustic Environment with Real Reverbration” • Wilson, Ben, “IBM Goes Own Way with PowerPC,” NewsFactor Network, May 14, 2002 • Apple: • “Xserve” • “Apple’s AltiVec Home Page”