ELEN 350 Computer Architecture Spring 2005 Introduction and Five Components of a Computer Adapted from CS 152 Spring 2002 UC Berkeley Adapted from CPSC 321 Fall 2004 Hank Walker, TAMU

Course Instructor Weiping Shi Class time: MWF 11:30am-12:20pm Office hour: TuF 3:00pm-5:00pm or by appt. 320 WERC, Tel: TA and Grader: TBA

Course Information [contd…] Grading: Projects, Assignments, Exams –Quizs10% –Midterm 30% –Final30% –Assignments30% Assignments include –Verilog (HDL) –MIPS (Assembly Programming) –More like project

Course Information [contd…] Required Text –Computer Organization and Design: The Hardware/Software Interface, Third Edition, David A. Patterson and John L. Hennessy, Morgan Kaufmann Publishers Reference Information –Check the course webpage for other materials and links

Course Information [contd…] Course Webpage –

Course Overview Arithmetic Single/multicycle Datapaths Computer Arithmetic Datapaths

Course Overview [contd…] IFetchDcdExecMemWB IFetchDcdExecMemWB IFetchDcdExecMemWB IFetchDcdExecMemWB PipeliningMemory Systems Performance Memory

What’s In It For Me ? In-depth understanding of the inner-workings of modern computers, their evolution, and trade- offs present at the hardware/software boundary. –Insight into fast/slow operations that are easy/hard to implementation hardware Experience with the design process in the context of a large complex (hardware) design. –Functional Spec --> Control & Datapath --> Physical implementation –Modern CAD tools

Computer Architecture - Definition Computer Architecture = ISA + MO Instruction Set Architecture –What the executable can “see” as underlying hardware –Logical View Machine Organization –How the hardware implements ISA ? –Physical View

Computer Architecture – Changing Definition 1950s to 1960s: Computer Architecture Course: –Computer Arithmetic 1970s to mid 1980s: Computer Architecture Course: –Instruction Set Design, especially ISA appropriate for compilers 1990s: Computer Architecture Course: Design of CPU, memory system, I/O system, Multiprocessors, Networks 2000s: Computer Architecture Course: –Non Von-Neumann architectures, Reconfiguration DNA Computing, Quantum Computing ????

Some Examples … °Digital Alpha(v1, v3) RIP soon °HP PA-RISC(v1.1, v2.0) RIP soon °Sun SPARC(v8, v9) °SGI MIPS(MIPS I, II, III, IV, V) °IA-16/32 (8086,286,386, 486, Pentium, MMX, SSE, …) °IA-64 (Itanium)1996-now °AMD64/EMT now °IBM POWER (PowerPC,…)1990-now °Many dead processor architectures live on in microcontrollers

CPSC 321 “What” is Computer Architecture ? I/O systemInstr. Set Proc. Compiler Operating System Application Digital Design Circuit Design Instruction Set Architecture Firmware Coordination of many levels of abstraction Under a rapidly changing set of forces Design, Measurement, and Evaluation Datapath & Control Layout

Impact of Changing ISA Early 1990’s Apple switched instruction set architecture of the Macintosh –From Motorola based machines –To PowerPC architecture Intel 80x86 Family: many implementations of same architecture –program written in 1978 for 8086 can be run on latest Pentium chip

Factors Affecting ISA ??? Computer Architecture Technology Programming Languages Operating Systems History Applications Cleverness

ISA: Critical Interface instruction set software hardware Examples: 80x86 50,000,000 vs. MIPS 5500,000 ???

The Big Picture Control Datapath Memory Processor Input Output Since 1946 all computers have had 5 components!!!

Example Organization TI SuperSPARC tm TMS390Z50 in Sun SPARCstation20 Floating-point Unit Integer Unit Inst Cache Ref MMU Data Cache Store Buffer Bus Interface SuperSPARC L2 $ CC MBus Module MBus L64852 MBus control M-S Adapter SBus DRAM Controller SBus DMA SCSI Ethernet STDIO serial kbd mouse audio RTC Floppy SBus Cards

Technology Trends Processor –logic capacity: about 30% per year –clock rate: about 20% per year Memory –DRAM capacity: about 60% per year (4x every 3 years) –Memory speed: about 10% per year –Cost per bit: improves about 25% per year Disk –capacity: about 60% per year –Total use of data: 100% per 9 months! Network Bandwidth –Bandwidth increasing more than 100% per year!

°In ~1985 the single-chip processor (32-bit) and the single-board computer emerged °In ~2002 started having multiple processor cores on a chip (IBM POWER4) DRAM YearSize Kb Kb Mb Mb Mb Mb Mb Gb Microprocessor Logic Density DRAM chip capacity Technology Trends

Smaller feature sizes – higher speed, density ECE/CS 752; copyright J. E. Smith, 2002 (Univ. of Wisconsin)

Technology Trends Number of transistors doubles every 18 months (amended to 24 months) ECE/CS 752; copyright J. E. Smith, 2002 (Univ. of Wisconsin)

The Role of Performance

Example of Performance Measure

Performance Metrics Response Time –Delay between start end end time of a task Throughput –Numbers of tasks per given time

Examples (Throughput/Performance) Replacing the processor with a faster version ? Adding additional processor to a system ?

Measuring Performance Wall-clock time –or- Total Execution Time CPU Time –User Time –System Time Try using time command on UNIX system

Relating the Metrics Performance = 1/Execution Time CPU Execution Time = CPU clock cycles for program x Clock cycle time CPU clock cycles = Instructions for a program x Average clock cycles per Instruction

Summary Computer Architecture = Instruction Set Architure + Machine Organization All computers consist of five components –Processor: (1) datapath and (2) control –(3) Memory –(4) Input devices and (5) Output devices Not all “memory” are created equally –Cache: fast (expensive) memory are placed closer to the processor –Main memory: less expensive memory--we can have more Interfaces are where the problems are - between functional units and between the computer and the outside world Need to design against constraints of performance, power, area and cost

Summary Performance “eye of the beholder” Running time = IC*CPI*cycle time –IC (instruction count), depends on instruction set and compiler –CPI (cycles per instruction), depends on architecture –Cycle time, depends on VLSI technology, not discussed in this course