TECH1001

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TECH1001

• Computer Architectures

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Types of Computer

• Many different types of operating system
• UNIX
• Usually found on main frames
• Linux
• Usually found on PCs
• MAC
• As found on Apple machines
• Windows 95, 98, 2000, NT, XP, ad-infinitum
• PC operating system
• Earlier versions of Windows were not true OS as
  they ran on top of DOS
• Others e.g. IBM mainframes OS,etc

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Types of Computer

• Usually, OS are written for specific
  architectures
• Some OS can be found running on different
  architectures
• Architecture in this sense can be thought of all
  the components in the computer
• Most important component is the CPU
• Intel CPU chips are the dominant CPU nowadays
• Examples are 8086, 386, 486, Pentium, etc

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PC Components

• CPU the heart of the system
• Usually defined by speed
• Memory
• RAM and ROM
• Examples of these?
• Interface cards / controller cards
• Examples of these?
• Buses

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Simplified PC Architecture
Central Processor Unit CPU
MEMORY
Disk Drive
Network Card
Disk Drive
Printer
Controller
Other devices
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PC Buses Standards

• Bus Pathway across which data can travel. Can
  be established between two or more computer
  elements.
• PC has a hierarchy of different buses (each
  slower bus is connected to a faster one above it)
• Each device in a system is connected to one of
  the buses. Some devices (primarily chipsets) act
  as bridges between the various buses.

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PC Buses Standards

• First bus connects the CPU with RAM
• Modern PCs call this the Host Bus
• Speed Width depend on the CPU the RAM type
  typically 64-bits 66-133MHz
• Expansion buses are a lot slower than the Host Bus

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PC Buses Standards

• Main buses in a modern system
• Processor BusAlso called front-side bus (FSB).
  Highest-speed bus in the system. Primarily used
  by between processor, memory, and chipset.
• PCI BusState-of-the-art I/O Bus
• AGP BusHigh-speed video bus
• ISA BusLegacy I/O Bus
• Various internal BusesLPC, AHA

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PC Buses Standards

• PC Buses are physically implemented as Tracks on
  a PCB or as signals on a connector
• PC Buses comprise the following
• Address Bus
• Data Bus
• Control Bus

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Common PC Buses
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PC Evolution 1

• Original PC (1983) had an 8086 CPU chip and 32
  Kbytes of memory.
• Command line interface
• Could not multitask
• Programming skills required to do pretty much
  anything
• Rudimentary WP (WordStar) and spreadsheet
  (SuperCalc) at best
• Processor was slow
• Developed into 286, 386 and 486
• Usually known as a PC/AT type

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Early PC/AT Architecture
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PC Evolution 2

• As time went on, applications required more
  speed, more bits for complicated applications,
  image processing, games, etc.
• At same time, interface was becoming more GUI
  based
• 286 / 386 had Windows 2
• 386 had Windows 3 and 3.1
• 486 had Windows 3.1, Win 95
• Intel developed Pentium to handle these new
  requirements

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PC Evolution 3

• Windows is the dominant OS
• Intensive GUI, command line for experts
• Very demanding of PC resources
• Lots of helpful ideas like pre-fetch which
  slow the machine down, logs kept of every file
  opened, ever-expanding Registry, etc.
• Pentium chip has evolved through Pentium I, II,
  III
• Very high CPU speeds, 64 bit buses, etc

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Modern PC Architecture