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Client/Server Architecture. Client/Server is advanced form of Distributed It is a way of looking at infrastructure “let the best processor do the job” PCs excel at ... Host systems excel at … So take an activity and let them share it Database Server PC makes query, server retrieves data

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client server architecture
Client/Server Architecture
  • Client/Server is advanced form of Distributed
    • It is a way of looking at infrastructure
    • “let the best processor do the job”
      • PCs excel at ...
      • Host systems excel at …
      • So take an activity and let them share it
    • Database Server
      • PC makes query, server retrieves data
    • Mail Server
      • PC creates mail, mail server routs it
    • Web Server
      • Server has web page, PC displays it
2 tier vs 3 tier architecture
2-Tier vs. 3 Tier Architecture
  • Client-Server is 2 tier
    • Applications are split up
      • part of software on client
      • part of software on server
    • Database is on server
    • Problems:
      • when client s/w is updated
      • as volume grows
  • 3 Tier Architecture
    • Separate platforms for three different functions
      • input, process and storage
three tier or n tier architecture
Three-Tier (or n-tier) architecture
  • Front-End (Input - what users see)
    • PCs or Thin Clients w/ GUI
      • Windows or Web-based Interface
      • Give access to middle tier, display what middle tier says
  • Middle Tier (Processing)
    • Application/transaction server(s)
    • Does authentication & processing
  • Back-End (Storage)
    • Database server(s) & SANs
  • Other possible layers
    • Legacy System(s) - old centralized apps
    • Load balancers
e commerce models pure plays
E-Commerce Models (pure plays)
  • Pure-play vs. Clicks-and-Mortar
  • Virtual Storefront – pseudo store
  • Online Marketplace or Electronic Broker
    • Where buyers and sellers meet, auctions
  • Information Broker
    • Provides/sells info on firms, revenue from firms
  • Transaction Broker
    • Process online sales for other firms (fee based)
  • Content Provider (syndicator)
    • Packages news, music… over the web
  • Online Service Provider
    • Access to internet + portal to other services
    • May sell member info
  • Virtual Community
    • Hosts chats, bulletin boards, etc.
it fundamentals

IT Fundamentals

1. Total Cost of Ownership

2. How Computers Work

3. Organizational Computing

4. Storage

5. Input/Output

6. Buying a Desktop Tutorial

total cost of ownership
Total Cost of Ownership
  • Hardware Acquisition - purchase price
  • Software Acquisition - license or s/w
  • Installation
  • Training
  • Support
  • Maintenance - cost to upgrade, repair
  • Infrastructure - link to nets, storage
  • Downtime - lost productivity
  • Space and Energy - utilities, facilities
tco takehome project
TCO Takehome Project
  • Research a Basic Unit and some upgrades (see next slide)
    • Online from 2 sources
      • Dell, Gateway, HP, Sony, Toshiba, IBM
      • BestBuy, CompUSA, CircuitCity
    • Find 2 systems that meet the specs (next slide)
      • From different manufacturers
  • Determine the cost of basic unit
  • Determine cost if upgraded RAM, Hard Drive & Monitor
  • Identify the warranty and extensions
  • Identify the service options and cost
  • Determine total cost of ownership per PC
    • (see other slide)
  • Give me a memo describing systems and your recommendation - which computer and why
basic unit and upgrades
Basic Unit and Upgrades
  • Basic Unit (Desktop)
    • CPU - 2+ gigahertz
    • Hard Drive - 40 gigabytes
    • RAM - 256 megabytes
    • Portable storage - CD-R/RW & DVD player
    • Monitor - 17 inch CRT
  • Upgrades
    • CPU - 3+ gigahertz
    • RAM - 512 megabytes
    • CD-R/RW & DVD-R/RW
    • Monitor - 17 inch flat screen (not flat panel)
other tco issues
Other TCO issues
  • We will want 30 units & 2 backups
  • 5 units need on-site service, the others will be shipped for repair
  • Should either come with XP pro or we will want to add it (use their price)
  • We have MS Office licenses ($65/PC)
  • We have other licenses ($150/PC)
  • A part-time support person will be hired ($10,000/yr, no benefits)
data representation vol speed
Data Representation : Vol/Speed
  • Computer devices are built using switches
    • Switches have two possible states - ON or OFF
      • Inside the computer
        • circuit open = 0 or OFF, circuit closed = 1 or ON
        • direction of current - one way is OFF, other is ON
      • Each switch is a BIT - value of a bit is 1 or 0
    • When you press a key on the keyboard…
      • a set of 0’s and 1’s are sent to CPU (ASCII code)
      • ex: 10011001 = Y
      • each character on keyboard = 1 byte (8 bit code)
        • 1Gbyte = more than a billion characters
  • Speed of Computer
    • Hertz = how fast things move (ex: MegaHrtz)
    • IPS (instructions per second, MIPS) = how much can do
      • FLOPS (floating pt ops) = calcs w/ decimal pts.
what a cpu does

Input

Devices

CPU

Output

Devices

Storage

Devices

What a CPU Does

Memory

what a cpu does1

Input

Devices

CPU

Storage

Devices

Output

Devices

What a CPU Does

Data Bus

Memory

External Bus

or I/O Bus

or Local/Expansion Bus

Internal Bus

typical steps
Typical Steps
  • What happens when you double-click on WP?
  • What happens as you type your report?
  • What happens when you save your report?
  • What happens when you turn off PC?
  • What happens when you open the file again?
what a cpu does2

Input

Devices

Output

Devices

Storage

Devices

What a CPU Does

Memory

disk

cache

CPU +

external

cache

internal

cache

DMA hard drive

disk

controller

Sound card &

Video card

computer platforms
Computer Platforms
  • High End
    • Supercomputers (cutting edge)
      • Parallel computing or super-cooled
      • Used in labs or high-end networking
    • Mainframe (business workhorse)
      • Massive memory/processing
  • Mid-range
    • Super-minis
    • Midrange server (dept wrkhorse)
    • Network Server (souped up PC for Lan)
  • Low-end
    • Workstation
    • Desktop
    • Handhelds
parallel processing
Parallel Processing
  • Slave Processors
    • add-on processors are not really parallel, CPU still in control
  • Fault Tolerant Processors
    • where multiple processors mirror each other
    • same transaction processed multiple times
  • True Parallel Processors
    • multiple CPUs
      • either share memory
      • or are virtual machines
primary storage fast to slow
Primary Storage (fast to slow)
  • Internal Cache Memory (L1 - inside CPU chip)
    • very fast volatile memory
    • stockpile data/instructions CPU uses next
  • External Cache Memory (L2 - outside CPU)
    • fast volatile memory
    • stockpile data/instructions for intl cache
  • RAM - Random Access Memory
    • volatile memory
    • holds what might be needed by CPU
    • generally expandable
  • Triple cache (L1/L2 in CPU, L3 outside)
secondary storage concepts
Secondary Storage Concepts
  • Memory vs Secondary Storage
    • Memory = primary or working storage
  • Writing vs. reading (output vs. input)
  • Removable vs. non-removable
    • whether medium is portable
  • Media (disk) vs. Drive
    • Media is the thing that is read
    • Drive does locating(access)/reading/writing
      • it also includes the drive controller (processor)
  • Backup
    • making a copy in case of disaster
  • Archiving
    • Older records stored on slower media
secondary storage features
Secondary Storage Features
  • No matter what technology used, there are features that never change
    • Format - sequential/direct
    • Capacity (volume of storage)
    • Size (of device/media)
    • Access time - how fast can locate
    • Read time - how quickly read
    • Ability to write/rewrite (& speed)
    • Portability of device/media
    • Fragility
    • Longevity
    • Cost of device/media
magnetic storage devices
Magnetic Storage Devices
  • Floppy Disks (thin plastic + iron oxide)
    • slow speed, low capacity
  • Zip Disk/EZFlyer
    • cassette larger than floppy, 250mb
  • Hard Disk (thick platter + rust)
    • vacuum sealed, high volume, non-removable
    • one platter or multiple platters stacked
  • Removable hard disks
    • Jaz/Orb (portable media)
    • semi-portable (swappable but fragile)
  • Tape Drives + Tape media
    • large reels, smaller cartridges
optical storage
Optical Storage
  • Laser beams read/write to plastic disk
    • create pits to represent 1 or on
    • higher capacity than magnetic
  • Compact Disc Standard
    • CD-ROM - read only
    • CD-R - Write Once, Read Many
    • CD-RW - erasable
      • phase change - heat plastic, removes pits
  • DVD - film industry standard
    • DVD-ROM, DVD-RAM
    • High capacity, two-sided
memory tech as sec storage
Memory Tech as Sec Storage
  • EEPROM
    • Electronically Erasable Programmable Memory
    • Originally developed to control machines in factories
  • Today use for secondary storage
    • Flash drives
    • Memory Sticks
    • Memory cards
    • Inside IPODs, MP3 players
storage in organizations
Storage in Organizations
  • Mass Storage Subsystems
    • Racks of
      • Large capacity tape cassettes
      • Large capacity diskettes in sealed cases
    • Robotic Arm that finds them
  • CD Jukeboxes or Magazines
  • RAID - Redundant Arrays of Inexpensive Discs
enterprise storage architectures
Enterprise Storage Architectures
  • Local Storage
    • Each server is connected to its own RAID
  • Network Attached Storage
    • RAID is attached to network so all servers can use it
    • typically NAS work at the file level
    • easy way to deal with growing storage needs
    • good when a lot of devices need common files
  • Storage Area Network
    • Create a separate network of RAID devices that can communicate with your server network (subnetwork)
    • good way to ease the load on your primary network
    • typically SAN work at the sub-file level
      • better for e-commerce (transaction data)
  • Web Storage = you use web to store stuff on vendor multiuser machine (server)
storage issues
Storage Issues
  • Everyday storage
    • Pick storage that fits
    • Security policies
  • Backup issues
    • What technology
    • Backup policies
      • When - how often
      • What - which data?
      • Where - how many media, reuse
  • Archiving issues
  • Infrastructure issues
    • Centralized, decentral, distrib
features of input output

. . .

.

. . .

.

. . .

Features of Input/Output
  • Input human understandable data turned into machine readable form (digitize)
  • Output machine readable data turned into human readable form
  • Importance of dots in I/O
    • We often use dots (pixels) to store characters or images
      • Resolution -- as the number of dots increases, the better the image
  • Importance of sampling in I/O
    • Continuous reality (video,sound)
    • Sample = snapshot
input devices
Input devices
  • Purpose: to translate incoming data into machine readable form (digitize)
    • Keyboard - translate keystroke to byte
    • Pointing devices - translate movement or pressure to bits
    • Graphic input - scanners
    • Audio Input - sounds to bits
      • microphones -- record only
      • voice-input devices -- interpret
    • Video Input - images to bits
      • Scanner - creates a map of dark/light dots
      • Digital Cameras - digitizes snapshot of reality
output devices
Output Devices
  • Video - translate bits to images for display
    • Monitors (Screen)
      • CRT, CRT Flat screen, LCD Flat panel
      • Electron gun, gas plasma, crystals
  • Hard copy - translate bits to characters or pictures on paper
    • Printers
      • ink-jet vs. laser
  • Audio - translate bits to sound
    • Speakers
    • Headsets
input in organizations
Input in Organizations
  • Different from home because:
  • Biggest problem - human beings…
input devices in organizations
Input Devices in Organizations
  • Input to aid humans
    • graphics tablet used with stylus
    • head/eye position trackers
    • touch screens
    • voice-input
  • Input to replace humans
    • OCR (optical character recognition)
    • Optical Codes -- ex: bar code
    • MICR (magnetic ink character recognition)
    • Magnetic stripe technology (ex: credit card)
    • Smart Cards
    • Intelligent Scanners
    • Handwriting Recognition Devices
output in organizations
Output in Organizations
  • Display
    • larger monitors for desktop
    • wall displays, flat panel screens
    • projectors
  • Printers
    • Fast/High Volume laser Printers
    • Color Laser
    • Impact printers
      • Dot-Matrix
      • Line printers
    • Thermal Printers
  • Plotters
output in organizations cont d
Output in Organizations (cont’d)
  • Audio
    • voice synthesizers
    • prerecorded voice
  • Video
    • CD-ROM burners
    • microfilm/microfiche
      • archival storage
hardware features and issues
Hardware Features and Issues
  • CPU
  • Memory
  • Secondary Storage
    • Policies
    • Technology
  • Input devices and organizations
  • Output
    • Printers
    • Monitors
    • Audio/Video
chip comparisons
Chip comparisons
  • Intel (Celeron, PentiumIII, Pentium 4)
      • Pentium 4
        • clock (1.4 - 2.8Ghz), 512 L2 (half speed)
          • 5.33 or 4 Ghz bus to memory
      • Pentium III
        • clock (850Mhz - 1.8), 512 L2, 1 or 1.33 Ghz bus
      • Celeron (value chipset)
        • Pentium chip + 128 L2 (full sped)
          • comparable bus
  • AMD (Duron & Athlon & Athlon XP)
        • double L1, same or double L2 (full speed)
        • similar clock speed
today s memory
Today’s Memory
  • SIMM, DIMM
    • bank of memory chips on a circuit board
  • Dynamic RAM (constant refreshing)
    • DRAM -- pipelined
    • S-DRAM - synchronized DRAM
    • DDR S-DRAM - dual channel (tick/tock)
    • R-DRAM (rambus) - memory processor
  • Static RAM (less refreshing needed)
      • costs more, use in cache
add on recommendations
Add-On Recommendations
  • Video Card or Graphics Accelerator
    • get AGP bus, AGP slot and AGP card
      • AGP = Advanced graphics port standard
    • memory (>=8 mb of DRAM or VRAM)
    • MPEG (motion picture std)
    • 3D engine
  • Sound Card
    • sampling rate -- higher the better
    • Wavetable vs. FM synthesis
        • is sound of instrument recorded or synthesized?
    • MIDI (music standard)
bus standards may need
Bus Standards May Need
  • Universal Serial Bus (USB) and Firewire
    • Still one character at a time but has a smarter processor
    • Port can handle multiple devices
      • Daisy Chain
      • USB Hub
    • Use with USB devices (ex: flash drive)
  • Other specialized buses
      • AGP (graphics),
      • Hard disk (SCSI, IDE),
      • Music (MIDI),
      • Network (T-connector or IRDA for infrared wireless)
secondary storage issues
Secondary Storage Issues
  • Disk Controllers
    • Some controllers let you attach more drives than others
      • IDE(ATAPI) -- 2 drives max, slow (5400 or 7200 RPM)
        • bus speed up to 100mhtz
      • SCSI -- 7 drives, faster (10k RPM)
      • SCSI Ultra -- > 14 drives, fastest
    • For home use IDE is fine
  • Photographic CD stds
    • Kodak Photo CD series
    • Flash PIX
screen issues
Screen Issues
  • Size of Screen
    • VIS -- viewable area (15’’)
  • Quality of Picture
    • Dot Pitch -- space between dots
      • .25 or smaller
    • Non-interlaced = less flicker
    • Refresh Rate -- 75 hz or better
    • Standard = SVGA
guidelines
Guidelines
  • CPU -- older one ok
    • especially if has cache (synch, full-speed?)
  • Monitor --
    • spend less now, upgrade later OR
    • Buy high, use w/ new PCs later
  • Hard Drive --
    • get a moderately large one because
    • can add more later (hard drive)
    • ask about number of IDE and SCSI controllers
guidelines cont d
Guidelines (cont’d)
  • Memory --
    • leave room to expand
    • considerations:
      • degree to which use multimedia
      • volume of software, files you will have
      • degree you use the internet
      • windows environment (XP = 128mb minimum)
  • Expansion
    • bays (how many unused doors on box?)
    • expansion slots (how many unused?)
    • power supply (200 watt or better)
      • may need more power from wall socket
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