Computer Architecture

Architecture & Organization

•          Architecture is those attributes visible to the programmer

–         Instruction set, number of bits used for data representation, I/O mechanisms, addressing techniques.

–         e.g. Is there a multiply instruction?

•          Organization is how features are implemented

–         Control signals, interfaces, memory technology.

–         e.g. Is there a hardware multiply unit or is it done by repeated addition?

•          All Intel x86 family share the same basic architecture

•          The IBM System/370 family share the same basic architecture

•          This gives code compatibility

–         At least backwards

•          Organization differs between different versions

Structure & Function

•          Structure is the way in which components relate to each other

•          Function is the operation of individual components as part of the structure

Computer Evolution and PerformanceENIAC – background

•          Electronic Numerical Integrator And Calculator

•          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 (not binary)

•          20 accumulators of 10 digits

•          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/Turing

•          Stored Program concept

•          Main memory storing programs and data

•          ALU operating on binary data

•          Control unit interpreting instructions from memory and executing

•          Input and output equipment operated by control unit

•          Princeton Institute for Advanced Studies

–         IAS

·         Completed 1952

 

Commercial Computers

•          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

IBM

•          Punched-card processing equipment

•          1953 - the 701

–         IBM’s first stored program computer

–         Scientific calculations

•          1955 - the 702

–         Business applications

•          Lead to 700/7000 series

Transistors

•          Replaced vacuum tubes

•          Smaller

•          Cheaper

•          Less heat dissipation

•          Solid State device

•          Made from Silicon (Sand)

•          Invented 1947 at Bell Labs

•          William Shockley et al.

Transistor Based Computers

•          Second generation machines

•          NCR & RCA produced small transistor machines

•          IBM 7000

•          DEC - 1957

–         Produced PDP-1

Microelectronics

•          Literally - “small electronics”

•          A computer is made up of gates, memory cells and interconnections

•          These can be manufactured on a semiconductor

•          e.g. silicon wafer

Generations of Computer

•          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 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

•          Cost of a chip has remained almost unchanged

•          Higher packing density means shorter electrical paths, giving higher performance

•          Smaller size gives increased flexibility

•          Reduced power and cooling requirements

• •          Fewer interconnections increases reliability
• 
  

IBM 360 series

•          1964

•          Replaced (& not compatible with) 7000 series

•          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)

–         Increased memory size

–         Increased cost

•          Multiplexed switch structure

Semiconductor Memory

•          1970

•          Fairchild

•          Size of a single core

–         i.e. 1 bit of magnetic core storage

•          Holds 256 bits

•          Non-destructive read

•          Much faster than core

•          Capacity approximately doubles each year

Intel

•          1971 - 4004

–         First microprocessor

–         All CPU components on a single chip

–         4 bit

•          Followed in 1972 by 8008

–         8 bit

–         Both designed for specific applications

•          1974 - 8080

–         Intel’s first general purpose microprocessor

Speeding it up

•          Pipelining

•          On board cache

•          On board L1 & L2 cache

•          Branch prediction

•          Data flow analysis

•          Speculative execution

Performance Mismatch

•          Processor speed increased

•          Memory capacity increased

•          Memory speed lags behind processor speed

Solutions

•          Increase number of bits retrieved at one time

–         Make DRAM “wider” rather than “deeper”

•          Change DRAM interface

–         Cache

•          Reduce frequency of memory access

–         More complex cache and cache on chip

•          Increase interconnection bandwidth

–         High speed buses

–         Hierarchy of buses