Lectures for 2nd Edition

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Lectures for 2nd Edition

• Note these lectures are often supplemented with
  other materials and also problems from the text
  worked out on the blackboard. Youll want to
  customize these lectures for your class. The
  student audience for these lectures have had
  assembly language programming and exposure to
  logic design
• Text in blue is by N. Guydosh
• Updated 1/22/04

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Chapter 1
3
Introduction

• Rapidly changing field
• vacuum tube -gt transistor -gt IC -gt VLSI (see
  section 1.4)
• doubling every 1.5 years memory capacity
  processor speed (Due to advances in
  technology and organization)
• Things youll be learning
• how computers work, a basic foundation
• how to analyze their performance (or how not to!)
• issues affecting modern processors (caches,
  pipelines)
• Why learn this stuff?
• you want to call yourself a computer scientist
• you want to build software people use (need
  performance)
• you need to make a purchasing decision or offer
  expert advice

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What is a computer?

• ComponentsWhat Joe Average sees
• input (mouse, keyboard)
• output (display, printer)
• memory (disk drives, DRAM, SRAM, CD)
• Network
• Our primary focus is to look under the covers
  the processor (datapath and control)
• implemented using millions of transistors
• Impossible to understand by looking at each
  transistor
• We need ... Abstractions

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Abstractions

• All information in a computer is encoded in 1s
  and 0s binary
• Dealing directly at the bit level is a near
  impossibility what was done in the first
  computers.
• We identify functional abstractions in the design
  of a computer
• For example the concept of an instruction which
  is an encoding of bits
• Identifying each instruction symbolically need
  for translation
• An assembler translates from symbolic to binary
  translation is 1 to 1 from symbolic to binary
  instructions easier than binary, but still too
  complex for writing algorithms.
• We now abstract to a high level language like C
  and use a compiler to translate to assembly or
  true machine instructions translation is now
  one C statement to many instructions.
• Ideally a high level language will allow
  portability across many hardware platforms
  simply recompile. There may be exceptions in
  real life.

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Abstraction

• Delving into the depths reveals more
  information
• An abstraction omits unneeded detail, helps us
  cope with complexityWhat are some of the
  details that appear in these familiar
  abstractions?

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Hardware/Software Interface

• By abstraction, we identify functional entities
  in a computer in both the hardware and software.
• The network of logic gates are abstracted into
  functional units such as an ALUs, registers,
  etc.
• The instruction set (see previous slide) is an
  abstraction of the overall function of the
  hardware design it actually defines (specifies)
  this hardware function.
• Ideally, we my think of the instruction set as a
  spec for the design of the hardware - design the
  hardware execute each instruction as efficiently
  as possible.
• In the real world, there may be some tradeoffs
  between the hardware design and the instruction
  set in the sense that hardware engineers may
  negotiate a change in an instruction but in
  general we think as the instruction set as
  relatively fixed.
• The relationship between the instruction set and
  the underlying hardware is called the
  hardware/software interface.

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What are Machine Structures?
Application (ex browser)
Operating
Compiler
System (Mac OS X)
Software
Assembler
Instruction Set Architecture
Hardware
I/O system
Processor
Memory
Datapath Control
Digital Design
Circuit Design
Acknowledgment From course CS61C, Berkeley By
Dan Garcia
transistors

• Coordination of many
• levels (layers) of abstraction

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Instruction Set Architecture

• A very important abstraction
• interface between hardware and low-level software
• standardizes instructions, machine language bit
  patterns, etc.
• advantage different implementations of the same
  architecture
• disadvantage sometimes prevents using new
  innovationsTrue or False Binary compatibility
  is extraordinarily important?
• Modern instruction set architectures
• 80x86/Pentium/K6(by AMD), PowerPC, DEC Alpha,
  MIPS, SPARC, HP

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Where we are headed

• Performance issues (Chapter 2) vocabulary and
  motivation
• A specific instruction set architecture (Chapter
  3)
• Arithmetic and how to build an ALU (Chapter 4)
• Constructing a processor to execute our
  instructions (Chapter 5)
• Pipelining to improve performance (Chapter 6)
• Memory caches and virtual memory (Chapter 7)
• I/O (Chapter 8)Key to a good grade reading
  the book!

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Anatomy 5 components of any Computer
Personal Computer
Keyboard, Mouse
Computer
Processor
Memory (where programs, data live
when running)
Devices
Disk (where programs, data live when not
running)
Input
Control (brain)
Datapath (brawn)
Output
Display, Printer
Acknowledgment From course CS61C, Berkeley By
Dan Garcia