1 Recap (from Previous Lecture)

2 Computer Architecture Computer Architecture involves 3 inter- related components – Instruction set architecture (ISA): The actual programmer-visible instruction set and serves as the boundary between the software and hardware. –Organization: includes the high-level aspects of a computer’s design such as: The memory system, the bus structure, and the internal CPU unit. –Hardware: Refers to the specifics of the machine such as detailed logic design and packaging technology.

Computer Architecture Technology Programming Languages Operating Systems History Applications Measurement & Evaluation Computer Architecture: Instruction Set Design Organization Hardware

4 Three Computing Markets Today Embedded Desktop Server

5 Desktop Computer Systems For “General-Purpose” Use –Word-Processing, Web surfing, Multimedia, etc. –Computation and Programming What’s in the box –Microprocessor –Memory - DRAM –Hard disk(s), CDROM/DVD, etc. –I/O - mouse, keyboard, video card, monitor, network, etc. Important Issues: –Optimized for price-performance –Performance - how fast is “fast enough”? –Cost –Basic capabilities (and expandability)

6 Server Computer Systems Large-Scale Services –File storage –Computation (e.g., supercomputers) –Transaction Processing, Web What’s in the Box(es) –Microprocessor(s) –Hard disks –Network Interface(s) Important issues: –Performance –Reliability, availability –Scalability One Rack-Mount PC Unit (Google uses ~ 10,000)

7 Embedded Computer Systems Computer as part of larger system –Consumer electronics, appliances –Networking, telecommunications –Automotive / aircraft control What’s in the box –Microcontroller / Microprocessor / System on Chip (SOC) –Memory: RAM, ROM; Disk –Special-purpose I/O (including analog stuff) Important issues –Cost, Power Consumption –Performance (against real-time constraints) –Reliability and Safety

8 Trends in Computer Architectures Computer architectures has been advancing at a very fast rate These advances can be attributed to advances in technology as well as advances in computer design – Advances in technology (e.g., microelectronics, VLSI, packaging, etc) have been fairly steady – Advances in computer design (e.g., ISA, Cache, RAID, ILP, etc.) have a much bigger impact (This is the theme of this class).

9 Trends in Technology Trends in Technology followed closely Moore’s Law “Transistor density of chips doubles every years” As a consequence of Moore’s Law: – Processor speed doubles every years – DRAM size doubles every years – Etc. target These constitute a target that the computer industry aim for.

10 Growth in processor performance VAX : 25%/year 1978 to 1986 RISC + x86: 52%/year 1986 to 2002 RISC + x86: 20%/year 2002 to present From Hennessy and Patterson, Computer Architecture: A Quantitative Approach, 4th edition, October, 2006

11 Integrated Circuits Capacity

12 Today: VLSI Microprocessors Pentium® 4 42M transistors / GHz 49-55W L=180nm Pentium® 4 “Northwood” 55M transistors / 2-2.5GHz 55W L=130nm Area=131mm 2 Process Shrinks Pentium® 4 “Prescott” 125M transistors / GHz 115W L=90nm Area=112mm 2

13 Today: VLSI Microprocessors Intel Itanium® 2 410M transistors / 1.3GHz / 130W L=130nm Area=374mm 2 Image source: Intel Corporation Intel Core 2 Duo 291M transistors / 2.67GHz / 65W L=65nm Area=143mm 2

14 MOORE’s LAW µProc 60%/yr. (2X/1.5yr) DRAM 9%/yr. (2X/10 yrs) DRAM CPU 1982 Processor-Memory Performance Gap: (grows 50% / year) Performance “Moore’s Law” Processor-DRAM Memory Gap (latency)

15 We need a balanced Computer System Memory Bus [Bandwidth] CPU MemorySecondary Storage [Clock Period, CPI, Instruction count] [Capacity, Cycle Time] [Capacity, Data Rate] Computer System Chain: As strong as its Weakest ring