CS 271 Computer Architecture Chapter 1: Introduction

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CS 271 (Computer Architecture)Chapter 1
Introduction

• CS 271 Computer Architecture
• Indiana University Purdue University Fort Wayne
• Mark Temte

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Introduction to computer architecture

• Basic concept
• Hardware and software are logically equivalent
• Any operation executed by some computer hardware
  can also be simulated in software
• Any operation performed by software can be build
  directly into the hardware of a computer system
• Note hardware implementation might be very
  complicated or costly

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Hardware computer system

• Very fast
• Typically has an instruction set consisting of
  simple operations
• MOV
• ADD
• BZ
• etc.
• Machine language for the instruction set
• Tedious to program
• Programs consist of a sequence of bits

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Virtual machine

• Call raw computer hardware M0 and the instruction
  set L0
• A virtual machine is a hypothetical computer M1
  whose machine language is L1
• More human oriented
• May be too expensive or complicated to actually
  build directly in hardware
• If so, L1 programs can still be written for M1
• However, such programs cannot be directly
  executed on M1

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Translation

• Translation makes L1 programs practical for
  computer systems that are too expensive to
  actually build in hardware
• Any program written in L1 must . . .
• either be translated to the L0 language prior
  to execution on M0
• or be interpreted by software written in L0 and
  running on M0

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Translation

• Translation is done by a compiler
• A complier is an L0 program running on M0 that
  translates the L1 program to L0
• The compiler output later runs on M0
• Interpreter
• An interpreter is an L0 program running on M0
• The interpreter translates and executes the L1
  program instruction-by-instruction

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Computer system

• Layers of virtual machines stacked on raw
  hardware
• Each virtual machine . . .
• provides an instruction set
• is translated to or interpreted by lower layers

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Contemporary multilevel machine

• Typical virtual machine levels
• High-level-language (HLL) machine level
• Assembly language machine level
• Operating system machine level
• Instruction set architecture (ISA) level
• Microarchitecture level
• Digital logic level
• The digital logic level is hardware with
  transistors, wires, power supply, etc.

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Evolution of multilevel machines

• Three level architecture
• ISA level
• Microprogram level
• Digital logic level
• Concept due to Maurice Wilkes (1951, Cambridge)
• Microprogram level
• Interprets ISA instructions using the digital
  logic level
• Very small instruction set
• Easier to construct than ISA level
• Built-in, unchangeable

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Evolution of multilevel machines

• Operating system level
• Adds instructions and features to the ISA level
• I/O instructions
• System macros
• Supervisor calls
• Etc.
• Added instructions are interpreted by the ISA
  level
• ISA instructions are executed directly
• (interpreted by the microprogram level)

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Evolution of multilevel machines

• CISC (Complex Instruction Set Computer)
• Golden age for microprogram level - 1960s and
  1970s
• Increasingly sophisticated microprogram level
  evolved
• Instructions for floating point, procedure
  call/return, etc.
• Execution became slower
• RISC (Reduced Instruction Set Computer)
• Eliminates the microprogram layer
• Small instruction set is directly executed
• Increased execution speed, but at a price
• Remove Inconvenient Stuff to the Compiler

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Milestones in computer architecture
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Computer generations

• 0th 1642 1945 Mechanical
• 1st 1945 1955 Vacuum tubes
• 2nd 1955 1965 Transistors
• 3rd 1965 1980 Integrated circuits
• 4th 1980 - VLSI, personal computers
• 5th 1970s - Invisible computers

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Moores Law

• The number of transistors on a chip doubles every
  18 months
• Gordon Moore (co-founder of Intel) 1965
• Not a law of nature
• Just an empirical observation
• Exponential growth at the rate of 60 per year
• Moores law has held from the 1960s until the
  present
• Increase from 103 to 108 transistors per chip

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Moores Law
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Spectrum of computers
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Examples of computer architectures
We will refer to these examples throughout the
semester
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Intel computer family
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Intel computer family
Moores law for (Intel) CPU chips.
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MCS-51 family
Members of the MCS-51 family.
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Metric units
The principal metric prefixes.