Chapter 2Computer Evolution and Performance

Contents• Key points• Brief history of computers

—Vacuum tubes—Transistors—ICs

• Designing for performance—microprocessor speed—performance balance

• Pentium and PowerPC evolution

Key points• Evolution of computers

— increased processor speed— decreased component size— increased memory size— increased I/O capacity and speed

• Increased processor speed— size of the components has been reduced— use of pipelining and parallel execution— use of speculative execution technique

• Balancing the performance of various elements— gains in performance in one area should not be handicapped by

a lag in other areas— processor speed vs. memory access time

– caches, wider data paths

ENIAC - background• Electronic Numerical Integrator And Computer

—first general-purpose electronic digital computer

• Eckert and Mauchly• University of Pennsylvania• Trajectory tables for weapons • Started 1943• Finished 1946

—Too late for war effort

• Used until 1955

ENIAC - details• Decimal machine(not binary)• 20 accumulators of 10 digits

—each digit is represented by 10 vacuum tubes

• Programmed manually by switches• 18,000 vacuum tubes• 30 tons• 15,000 square feet• 140 KW power consumption• 5,000 additions per second

von Neumann Machine• Stored Program concept

—not setting switches manually from outside—but storing the instructions and data inside

• John von Neumann—IAS computer

– Started 1946, completed 1952– Prototype of all subsequent computers

• General structure of IAS computer—Main memory storing programs and data—ALU operating on binary data—Control unit interpreting instructions —I/O equipment operated by control unit

Structure of von Neumann machine

IAS - details

• 1000 x 40 bit words—Binary number—2 x 20 bit instructions

• Set of registers (storage in CPU)—Memory Buffer Register—Memory Address Register—Instruction Register—Instruction Buffer Register—Program Counter—Accumulator—Multiplier Quotient

Structure of IAS –detail

IAS - instructions• Total of 21 instructions(Table 2.1)

—Data transfer—Unconditional branch—Conditional branch—Arithmetic—Address modify

Commercial Computers - UNIVAC• 1947 - Eckert-Mauchly Computer Corporation

—UNIVAC I (Universal Automatic Computer)—US Bureau of Census 1950 calculations—Became part of Sperry-Rand Corporation

• Late 1950s - UNIVAC II—Faster, more memory—Upward compatible with the older machines

Commercial Computers - IBM• Punched-card processing equipment• 1953 - 701

—IBM’s first stored program computer—Scientific calculations

• 1955 - 702—Business applications

• Lead to 7000 series

Transistors• Replaced vacuum tubes• Smaller• Cheaper• Less heat dissipation• Solid State device made from Silicon• Invented 1947 at Bell Labs• William Shockley et al.

Transistor Based Computers• Second generation machines• NCR & RCA produced small transistor machines• IBM followed with 7000 series• DEC - 1957

—Produced PDP-1—mini-computer phenomenon began

IBM 7094• From 700 series to 7094 series

—increased performance—increased capacity—lower cost

Microelectronics• What do we need for a digital computer?

— they need to perform storage, movement, processing, and control functions

— gates and memory cells

• Gate— a device that implements a simple logical function

• Memory cell— a device that can store one bit of data

• Which functions are supported by which device?— Storage : provided by memory cells— Processing : provided by gates— Movement : provided by the interconnection(paths) between

components— Control : control signals can be carried by the interconnection

Computer Generations• Vacuum tube - 1946-1957• Transistor - 1958-1964• Small scale integration - 1965 on

—Up to 100 devices on a chip• Medium scale integration - to 1971

—100-3,000 devices on a chip• Large scale integration - 1971-1977

—3,000 - 100,000 devices on a chip• Very large scale integration - 1978 to date

—100,000 - 100,000,000 devices on a chip• Ultra large scale integration

—Over 100,000,000 devices on a chip

Moore’s Law• Increased density of components on a chip• Gordon Moore - cofounder of Intel• Number of transistors on a chip will double every year• Since 1970’s development has slowed a little

— Number of transistors doubles every 18 months

• Consequences of Moore’s law— Cost of a chip has remained almost unchanged— Higher packing density means shorter electrical paths,

increasing operating speed— Smaller size, making it more convenient to place in a variety of

environments— Reduced power and cooling requirements— Fewer interconnections increases reliability

Growth in CPU Transistor Count

IBM 360 series• 1964• Replaced & not compatible with 7000 series

—to produce a system with new IC technology

• First planned “family” of computers—Similar or identical instruction sets—Similar or identical O/S—Increasing speed—Increasing number of I/O ports (i.e. more terminals)—Increasing memory size —Increasing cost

DEC PDP-8• 1964• First minicomputer

—could not do everything the mainframe could

• Small enough to sit on a lab bench• $16,000

—$100k+ for IBM 360

• Use bus structure—Omnibus

DEC - PDP-8 Bus Structure

OMNIBUS

ConsoleController

CPU Main Memory I/OModule

I/OModule

Semiconductor Memory• 1970 : from core to ICs• Fairchild• Size of a single core could hold 256 bits• Non-destructive read(compared to destructive

core)• Much faster than core• Capacity approximately doubles each year

—since 1970, 11 generations—1K, 4K, 16K, 64K, 256K, 1M, 4M, 16M, 64M, 256M,

1G

Speeding it up• Besides the number of transistors in a chip…

—Pipelining—On board cache

– L1 & L2 cache

—Branch prediction– if the guess is right most of the time, we can prefetch the

correct instructions

—Data flow analysis– analyze which instructions are dependent on which– create an optimized schedule of instructions

—Speculative execution– speculatively execute instructions ahead of their actual

appearance

Performance Mismatch• Processor speed increased• Memory capacity increased• Memory speed lags behind processor speed

DRAM and Processor Characteristics

Solutions• Increase number of bits retrieved at one time

—Using wide bus data paths

• Change DRAM interface—Cache

• Reduce frequency of memory access—More complex cache

• Increase interconnection bandwidth—High speed buses—Hierarchy of buses

Pentium Evolution (1)• 8080

— first general purpose microprocessor— 8 bit data path— Used in the first personal computer – Altair

• 8086— much more powerful— 16 bit data path and registers— instruction cache for prefetching few instructions— 8088 (8 bit external bus) used in the first IBM PC

• 80286— 16 MB memory addressable

• 80386— Intel’s first 32 bit processor— Support multitasking

Pentium Evolution (2)• 80486

—sophisticated powerful cache and instruction pipelining

—built-in math coprocessor• Pentium

—superscalar technique– multiple instructions executed in parallel

• Pentium Pro—increased superscalar organization—aggressive register renaming—branch prediction—data flow analysis—speculative execution

Pentium Evolution (3)• Pentium II

—MMX technology– graphics, video & audio processing

• Pentium III—Additional floating point instructions for 3D graphics

• Pentium 4

—Further floating point and multimedia enhancements• Itanium

—64 bit machine with IA-64 architecture—details in Chap 15

• See Intel web pages for detailed information on processors

PowerPC (1)• A superscalar RISC system

—companies involved– IBM, Motorola, Apple

—used in Apple Macintosh machines

• 601—32 bit machine

• 603—intended for low-end desktop and portable computers

• 604—uses advanced superscalar techniques

PowerPC (2)• 620

—intended for high-end servers—full 64 bit architecture

– 64 bit registers and data paths

• 740/750—also known as G3 processor—two level cache

• G4—increased parallelism and speed

Internet Resources• http://www.intel.com/

—Search for the Intel Museum

• http://www.ibm.com• http://www.dec.com• Charles Babbage Institute• PowerPC• Intel Developer Home

Problem Solving Assignment 1• Solve the following problems of Chapter 2:

— 1

Reading Assignment 1• Read and report on the following paper from the

research literature. Your report should be one to two pages long; three-quarters of the report should summarize the paper, and one-quarter of the report should be a critique. Introduce your report with a formal citation of the paper, using the format found in the References section of the textbook.

• Flynn, M. “What’s Ahead in Computer Design?”Euromicro ‘97 Proceedings, September 1997. Http://umunhum.stanford.edu/papers.html