Information Technology Infrastructure

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Information Technology Infrastructure

• Hardware and Software and Telecommunications

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Computer Generations

• Four major generations
• Each distinguished by different base technology
• Each generation significantly improved
  computational power while lowering costs
• Cost of 100,000 calculations
• 1950s several dollars
• 1980s .025
• 1995 .00004

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Computer Generations

• First Generation (1946-1956)
• Based on vacuum tube technologies
• Huge tubes that burnt out quickly
• Main memory 2000 bytes
• Rotating drums used for hard disk and punch cards
  used for external storage
• Typically used for limited scientific and
  engineering work

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Computer Generations

• Second Generation (1957-1963)
• Based on transistor technology
• Smaller than tubes, generated less heat
• Main memory reached 32 KB
• Speeds of up to 300,000 instructions per second
• Used for science, engineering and some business
  tasks (payroll and billing)

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Computer Generations

• Third Generation (1964-1979)
• Based on integrated circuits technology
• Made by printing hundreds (later, thousands) of
  transistors on a silicon chip
• Known as semiconductors
• RAM expanded to 2MB
• Speeds of upto 5 MIPs
• Introduced software that could be used without
  extensive technical training

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Computer Generations

• Fourth Generation (1980-present)
• Based on VLSI (very large-scale integrated
  circuits) technology
• Packs tens of millions of transistors on a single
  circuit
• Memory, logic, and control on a single chip
  hence the term, microprocessor
• Allowed the development of smaller machines

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Power, Cost and Moores Law

• 1965 Gordon Moore of Fairchild Semiconductors
  predicted that the number of transistors would
  double every 18-24 months
• This has held for nearly 30 years
• Intel plans to unveil a one-billion transistor
  chip capable of 100,000 MIPs in 2011
• Check site below for more information
• http//www.intel.com/labs/eml/index.htm

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What is a Computer System?
Central Processing Unit(ALU CU)
Input Devices
Secondary Storage
buses
Communication Devices
Output Devices
Primary Storage
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The CPU

• The Central Processing Unit (CPU)
• Manipulation of numbers, letters, symbols
• Controls other parts of the computer system
• Consists of
• Arithmetic Logic Unit (ALU)
• Logical and arithmetic operations
• Control Unit (CU)
• Coordinates and controls other parts of system
• Reads programs and directs other parts to
  performs tasks requested by program (machine
  cycle)

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CPU- How Does it Work?

• Control Unit initiates fetch and execute cycles
• Code cache very fast memory on CPU chip
• RAM copies instructions here for fast retrieval
• Data cache fast access to small amounts of data
• Instruction location counter points to next
  instruction
• Instruction decoder analyzes what each
  instruction means
• Integer and floating point unit does math
• ALU does logical comparisons

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Primary Storage

• Sometimes referred to as primary memory or main
  memory
• Three functions
• stores all or part of the program being used by
  the CPU
• stores the operating system programs that manage
  the computer
• store the data needed for the program being run
• Random Access
• Volatile

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What is cache?

• Moving data between RAM and CPU can take several
  clock cycles
• To do it in a single cycle needs high speed
  memory (expensive)
• Caches are small holding areas on the chip using
  high speed memory.
• Chip designer add cache (called L1 cache) on the
  chip
• Manufacturers sometimes add L2 cache which may or
  may not be on the chip.

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Linking the CPU, Primary Storage, and other
devices

• Three kinds of buses
• Data bus (moves data to and from RAM)
• Address bus (signals for locating a specific
  address in RAM)
• Control bus (signals to specify read/write
  operations for RAM and peripheral devices)

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Processing Speed

• Determined in part by
• Word length (number of bits than can processed at
  one time by the machine)
• Cycle speed (measured in MHz internal beat set
  by control unit)
• Data bus width (number of bits that can be moved
  at the same time)
• Computation on more bits at a time
• Cache memory
• Floating Point calculations can be performed on
  hardware
• Number of transistors
• Pentium 4 has about 55 million on a single chip
• Parallel processing

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Categories of Computers

• Mainframes
• Largest of the computer types
• Massive memory
• Rapid processing power
• Business, science, engineering applications
• Demise greatly exaggerated

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Categories of Computers

• Minicomputers
• Mid-range
• Originally DEC aimed at getting a slice of IBMs
  mainframe market (1957)
• By 1969, scaled down version referred to as
  minicomputers

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Categories of Computers

• Personal Computers
• Sometimes called a microcomputer
• Local storage and processing
• Workstations
• Powerful math and graphics capabilities
• Typical of engineering and design projects

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Categories of Computers

• Supercomputers
• Can perform billions of calculations per second
  (GFLOP)
• Based on parallel processing
• Originally designed for military for weapon
  systems

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Massively Parallel Computing(Fifth Generation)

• Thousands of processors
• Work in concert
• Split the workload and process in parallel

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Cluster Computing

• Link computers together for faster performance or
  more reliable use
• Two types
• High availability clustering
• Server A fails, Server B takes over without pause
• Performance clustering
• Servers A and B work together on single problem
• Finish more quickly than either one could do
  alone

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Categories of Computers

• Network Computers
• Also called thin clients
• Minimal storage and processing
• Download data and software from central server or
  Internet
• Eliminates need for secondary storage devices
• Aimed at reducing Total Cost of Ownership

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The Future of Hardware

• Limited by physics and economics
• Physics
• Transistors currently etched using ultraviolet
  optical lithography
• Can go down to 130 nanometers (400 atoms)
• Below 100 nanometers wavelengths of light too
  big IBM using X-rays Intel using Xenon Lucent
  using beams of electrons
• Intel has begun shipping the 90 nm technology in
  4th quarter of 2003
• Economics
• As size decreases, cost of fabrication increases
• Currently, plants cost about 2.5b
• For lt100 nanometers, typically shoots to 10b
• Need for affordable scaling

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Software The second building block
My software never has bugs it just develops
random features --Source unknown
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What are the different types of software?

• Systems software
• special software programs that help run the
  computer
• Application software
• programs written to complete a specific task
• End-User Developed software
• software that allows non-technical users to
  develop programs

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How do they work?
Source Code
Executable
compiler
Object Code
linkage
Other modules
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Software Generations
human-oriented
Natural Languages
4GLs
Third Generation Languages
Assembly Languages
Machine Language
computer-oriented
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Open Source vs. Proprietary Software

• What is open source?
• Refers to way source code is developed and shared
  by a community
• OSS is transparent and you have ability to change
  it yourself
• PS is privately owned changes must go through
  them
• Open Source movement started by Richard Stallman
  of Free Software Foundation

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Types of freedom (from www.fsf.org)

• The freedom to run the program, for any purpose
  (freedom 0).
• The freedom to study how the program works, and
  adapt it to your needs (freedom 1). Access to the
  source code is a precondition for this.
• The freedom to redistribute copies so you can
  help your neighbor (freedom 2).
• The freedom to improve the program, and release
  your improvements to the public, so that the
  whole community benefits (freedom 3). Access to
  the source code is a precondition for this.

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OOS Advantages

• Often free or low cost
• Interoperability
• Active support community
• Powerful and scalable
• "Free, as in speech".
• Ability to modify code
• Transparency of code

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OOS Disadvantages

• Can be less "polished" or "user-friendly" than
  Proprietary Software.
• Requires learning anew each time a change is made
• Is it worth the risk? Everyone is using Microsoft
  should you change
• It's not as well known as Proprietary Software.