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					     Troubleshooting
         (continued)

  Making your own
flow chart/punch list
               Installation Overview

1. Install device or add-on card.
2. Is it legacy? Configure system
   resources.
3. Install device driver.
4. Confirm hardware/software
   configuration settings.
5. Install application software.
6. Test the configuration change.
                                        Presented by Phillip Schein for Accutech, 2002
        Some material excerpted without permission from Microsoft, Oracle courseware
  Installing a hardware device
1. Protect PC from ESD.
2. Modify PC chassis to accommodate device.
3. Insert device/add-on card in appropriate
   location inside chassis.
4. Secure the device and connect power,
   address, and data lines.
5. If appropriate, configure resources on device.
6. If appropriate, confirm BIOS settings.
7. If appropriate, confirm system settings.
8. Test the device.
                                          Presented by Phillip Schein for Accutech, 2002
          Some material excerpted without permission from Microsoft, Oracle courseware
                           Steps to
            Define/Isolate/Resolve
1. Define the problem scope
    hard/soft; power, addressing, data, etc.
    Determine the best “level” for resolution
2. Isolate ONE suspect source at a time
3. Resolve your defined problem scope; if
   possible, replicate on a different system
4. Communicate/Transmit/document
   DIRECT – a troubleshooting acronym
                                         Presented by Phillip Schein for Accutech, 2002
         Some material excerpted without permission from Microsoft, Oracle courseware
  Troubleshooting Guidelines

1. Visually inspect and                                   Fast/Cheap
   manipulate (pull/reseat)                               /on-site
2. Use a “good” FRU where
   appropriate for testing
3. Confirm BIOS/OS
   configuration
                                                           Expensive
4. Replace labor-intensive                                 /off-site
   and/or expensive parts
                                        Presented by Phillip Schein for Accutech, 2002
        Some material excerpted without permission from Microsoft, Oracle courseware
                                  1st Round
                        - Visual inspection
1. Have you “traced” all functional busses?
2. Follow the physical paths supporting power
   and address/data transfers
3. Isolate and reseat each connector
4. Where appropriate, use either a different
   connector or different expansion slot

Do you know the “typical” symptoms
of a bad cable connection?
                                         Presented by Phillip Schein for Accutech, 2002
         Some material excerpted without permission from Microsoft, Oracle courseware
                   2nd Round
  - BIOS config. management

1. Confirm CMOS settings for
   power and speeds
2. Confirm CMOS settings for
   expansion bus devices. Do you have
   legacy devices in the system?
   What are the “typical” symptoms
   of poor or incorrect BIOS settings?
                                        Presented by Phillip Schein for Accutech, 2002
        Some material excerpted without permission from Microsoft, Oracle courseware
                     3rd Round
      - OS config. management
1. Using Device Manager, confirm
   system resource allocations
2. Confirm the proper installation and current
   versions of driver software
3. Typically keep driver software updated and
   current. Document ALL software updates.

     What are the “typical” symptoms
     of an incorrect driver?
                                          Presented by Phillip Schein for Accutech, 2002
          Some material excerpted without permission from Microsoft, Oracle courseware
                                Presented by Phillip Schein for Accutech, 2002
Some material excerpted without permission from Microsoft, Oracle courseware
                                                              Topics

Sound cards
Keyboards
Pointing Devices
Modem cards




                                        Presented by Phillip Schein for Accutech, 2002
        Some material excerpted without permission from Microsoft, Oracle courseware
            A Generic Sound Card
                                                                                MIC
                                                                Audio
                       ADC                                                      Line
                                                                Amp              in

ROM                         Synthesizer                         CD Audio
           DSP                                                  Audio           Spkr
RAM                         Mixer/Filter                                        Line
                                                                Amp              out

                                                     MIDI/joystick
 Bus Interface circuits                                interface

                PCI or Expansion Bus

                                         Presented by Phillip Schein for Accutech, 2002
         Some material excerpted without permission from Microsoft, Oracle courseware
                                               Sound Card
 Sound waves translated to analog electrical signals via
  microphone
 Analog signals amplified by sound card then digitized
 Data and control information is compiled into a file
  format, WAV, and saved to a storage device like drive
  or CDROM
 WAV file read and translated back to analog form. If
  stereo, data divided into two channels separately
  converted to analog signals, amplified, then sent to
  speakers.
 Speakers convert analog signals to pressure waves.

                                          Presented by Phillip Schein for Accutech, 2002
          Some material excerpted without permission from Microsoft, Oracle courseware
                      Sampling (digitization)
An analog wave is measured periodically and voltages are
   converted to digital numbers by an analog-to-digital
   converter (ADC).
A sound file is the digital equivalent of an analog
   waveform.
One issue is capturing sufficient wave levels to reproduce
   analog wave. Distortion resulting from low sampling is
   called aliasing.
Sampling should occur twice as fast as highest frequency.
   Sampling rates should be at least 44 kHz. High rates
   require more disk space.
Precision of each each sample (bit depth) is also
   important. Most boards have a 16-bit depth
   (2^16 or 65,536 levels).
                                           Presented by Phillip Schein for Accutech, 2002
           Some material excerpted without permission from Microsoft, Oracle courseware
                                                                         MIDI
Musical instrument digital interface (MIDI) is a
  standard protocol defining hardware, software, and
  electrical connections using a synthesizer chip.
A MIDI file is a set of instructions for playing musical
  notes including duration, pitch, and timing
  specifications using relatively small storage space
  compared to WAV files. MIDI is not a sound but a
  “blueprint” for the sound or sheet music.
The blueprint includes voices of individual instruments
  and how to play the music. Sound cards can have, for
  example, 32 voices playing simultaneously;
  polyphony.

                                            Presented by Phillip Schein for Accutech, 2002
            Some material excerpted without permission from Microsoft, Oracle courseware
                                            A sound card
 On a sound card, the core component is the digital
  signal processor (DSP) which is a chip designed to
  manipulate digital data.
 A ROM chip contains programs that run the DSP and
  other circuitry on the board. RAM provides support for
  DSP operations and a buffer for data transfer to the
  system expansion bus.
 Incoming signals from a microphone pass through an
  amplification stage and then to the ADC.
 Signals from the “line” input are typically stronger and
  require less amplification.
 Output signals are sent to a mixer for each speaker
  (stereo) before leaving the board where CD audio, DSP
  sound output, and synthesizer output are combined in a
  single analog channel.
                                           Presented by Phillip Schein for Accutech, 2002
           Some material excerpted without permission from Microsoft, Oracle courseware
                         Audio Terminology
Decibels (dB) – logarithmic; increasing stereo power
   does not increase loudness linearly. Small changes in
   dB relate to large changes in “power” or wattage.
Frequency response is range of frequencies handled
   uniformly. Sound output is stable across some
   working frequency range. The cheaper the card, the
   greater the roll-off of signal strength; bass and treble
   are weak.
Signal-to-Noise Ratio (SNR) is maximum undistorted
   signal divided by electronic noise (hum and hiss)
   generated by the board in dB. Boards with SNR
   below 75dB have audible noise.
Total Harmonic Distortion (THD) is the unwanted
   harmonic frequencies produced. Harmonic frequencies
   or overtones are integer multiples of original signals.
                                           Presented by Phillip Schein for Accutech, 2002
           Some material excerpted without permission from Microsoft, Oracle courseware
                                          Microphones
Dynamic – usually hand-held or desktop. Large response
  range and better sound than condenser. Diaphragm
  elements can create electric current for sound board
  signal.
Condenser – Typically come with computers, not as good
  a response rang as dynamic mikes; smaller diaphragm.
  Uses “phantom” low-level power from the sound
  board.
Electret condenser –Condenser mikes with built-in
  power.

Microphones must conform to the board specifications.
   Not all sound cards have control to enable/disable
            power to support different mikes.
                                         Presented by Phillip Schein for Accutech, 2002
         Some material excerpted without permission from Microsoft, Oracle courseware
 Sound cabling connections
Speaker output
Microphone input
Line input
CD audio cable between CDROM and
 board
CDROM drive interface
MIDI or joystick (15-pin)


                                     Presented by Phillip Schein for Accutech, 2002
     Some material excerpted without permission from Microsoft, Oracle courseware
              Sound Board Punchlist
 PHYSICAL
    Confirm speakers connection and power. Hisses and hums can
     be caused by EMI or RFI
    Confirm volume levels on the speakers
    Confirm mixer and master volume levels on the PC
    Confirm physical connection of boards and installation (and
     date) of drivers
    Confirm BIOS settings for sound devices
 Driver
    Confirm sound files are installed correctly and the file is a
     valid .MID or WAV
 Support Resources
    Confirm system resource allocations do not have conflicts
    Confirm applications have correctly selected and configured
     the sound devices
                                             Presented by Phillip Schein for Accutech, 2002
             Some material excerpted without permission from Microsoft, Oracle courseware
                                Presented by Phillip Schein for Accutech, 2002
Some material excerpted without permission from Microsoft, Oracle courseware
                                                    Keyboards
 Mechanical vs Membrane key switch on keyboards
 Keyboard interface chip (onboard) interprets the
  keyboard matrix and sends single byte key (or scan)
  code in form of a make and a break code (Typematic
  Delay and Repeat Rate in KB properties)
 Keyboard controller (KBCs aka virtual “8042”) now
  incorporated into chipset; support different languages.
 QWERTY vs Dvorak (AOEUI in left home row)
 Important signals are KBCLOCK, KBDATA, and
  signal ground.
 Older XT keyboards were simplex; AT keyboards are
  half duplex for programming keys.
 What happens during POST when a KB fails?
                                            Presented by Phillip Schein for Accutech, 2002
            Some material excerpted without permission from Microsoft, Oracle courseware
                                                              Mouse
One of a family of pointing devices (mouse,
  trackball) that move a cursor across the GUI.
  A software driver generates the cursor and,
  based on hardware-generated signals, moves
  the cursor in the positional space of the
  display area. Mouse gestures (clicks, drags,
  drops) sometimes in combination with
  keyboard input, activate programmed
  methods associated with icons on the GUI.
Three components – a “hard” signal generator, a
  software driver, and an application interface.

                                        Presented by Phillip Schein for Accutech, 2002
        Some material excerpted without permission from Microsoft, Oracle courseware
                    Mouse Construction
A hard rubber ball contacts two actuators that
  register movement in an X (horizontal, “left to
  right”) and Y (vertical, up or down) coordinate
  system. The generated signals of the ball AND
  mouse buttons represent movement and action
  correlating with cursor movement and mouse
  gestures on the GUI.
Mechanical vs Optomechanical sensors -
  optoisolator

                                          Presented by Phillip Schein for Accutech, 2002
          Some material excerpted without permission from Microsoft, Oracle courseware
                   Sensor Layout
of optomechanical pointing device

                        Roller                                   Y-pulses




    Roller            Mouse Ball



                                                          Optoisolator


     X - pulses
                                     Presented by Phillip Schein for Accutech, 2002
     Some material excerpted without permission from Microsoft, Oracle courseware
         Pointing Device Interfaces
Legacy
Serial mouse – using DB9F or DB25F in COM
  ports
Bus mouse – uses it’s own standalone controller
  board and dedicated bus connector (mini-
  DIN)
Non-legacy
 6-pin mini-DIN design; connector used to
  provide interface for mouse AND KBs on PC
 USB connection off a USB hub or other device

                                         Presented by Phillip Schein for Accutech, 2002
         Some material excerpted without permission from Microsoft, Oracle courseware
                                   Pointing Device
                                         Punchlist
For USB:
    Check OS version, check software driver
    Check product firmware version.
    Confirm Universal Serial Bus Controller is
     recognized by Device Manager
    Confirm USB controller and ports are enabled and
     recognized by BIOS/OS
Confirm settings of pointing device
Confirm software drivers are loaded properly


                                           Presented by Phillip Schein for Accutech, 2002
           Some material excerpted without permission from Microsoft, Oracle courseware
                                Presented by Phillip Schein for Accutech, 2002
Some material excerpted without permission from Microsoft, Oracle courseware
                                   Video Punchlist
The Video Graphics card – hard
    VRAM – type, quantity, speed, access
    bus connection (AGP), chipset, RAMDAC only for
     analog
Supplemental processing support - hard
    accelerator cards
Trend toward incorporating more graphics capabilities
  into chipsets – Intel 810 / 815 incorporates a GMH
The Monitor – hard
    CRT (analog) / Flat panel (digital)
The Device drivers - soft
                                           Presented by Phillip Schein for Accutech, 2002
           Some material excerpted without permission from Microsoft, Oracle courseware
                             OS and I/O output
 Memory
                                                                 RAMDAC


Video card              Video        Monitor
                        Driver       Driver                      Analog
                                                                 Display
                                                                 Monitor
 Chipset

                        Operating
                         System
Service properties – resolution, color depth, refresh rate
                                           Presented by Phillip Schein for Accutech, 2002
           Some material excerpted without permission from Microsoft, Oracle courseware
                                   Memory Issues

Resolution (Bit Map Size)                                     RAM
640 x480                                                      1.0 MB
800 x 600 (standard 16 color)                                 1.5 MB
1024 x 768 (preferred)                                        > 2.0 MB

VRAM is “double-celled” RAM allowing
  simultaneous read/write
Standard configs – minimum 4 MB/ 8 MB
                                         Presented by Phillip Schein for Accutech, 2002
         Some material excerpted without permission from Microsoft, Oracle courseware
                                                        RAMDAC
Converts digital RAM to analog CRT signals

                         RAM
  OnBoard               Digital                                 Analog
  Memory              to Analog                                 Display
 RAM/VRAM
                      Converter


   At 16 bits, a screen image 1024 x 768 requires
    a 1.5 MB bit map. This bit map is optimally
   refreshed (vertical refresh) 75 times a second.


                                           Presented by Phillip Schein for Accutech, 2002
           Some material excerpted without permission from Microsoft, Oracle courseware
           Video Graphics Cards
Display modes
  – GUI or TUI
Resolution
  – pixel count
Color palette
  – TTL vs Analog signals
Scan rate
  – Monitors and cards must agree


                                       Presented by Phillip Schein for Accutech, 2002
       Some material excerpted without permission from Microsoft, Oracle courseware
                                       The monitors
Transistor to Transistor Logic (TTL) -
  Monochrome Display Adapter (MDA)
     - 2^2 (4 colors) (actually one color/shades)
  Hercules Graphics Card (CGA)
  Color Graphics Adapter (CGA)
     - 2^4 (16 colors) (RGB+intensity)
  Enhanced Graphics Adapter (EGA)
Analog signal -
  Video Graphics Array (VGA)
  SVGA and UVGA – lack of standards
                                       Presented by Phillip Schein for Accutech, 2002
       Some material excerpted without permission from Microsoft, Oracle courseware
  CRT- based Video Monitors

Legacy -
  TTL- based MDA / CGA / EGA
   – up to 640 x 350 pixels
Non- Legacy -
  Analog-based VGA is THE basic
   configuration
  Super VGA is current standard
                                       Presented by Phillip Schein for Accutech, 2002
       Some material excerpted without permission from Microsoft, Oracle courseware
                                                      The Works

                                                                 Grille or
RAM DAC                                                       (shadow mask)
 – digital to analog

         H/V                                                       Pixels on
3 Guns            Magnetic electron
       Deflection                                                  Phosphor
 RGB
         Coils
                   Yoke stream
                                                                    Screen
Analog signal
scans across screen
directed by deflection coils

                                             Presented by Phillip Schein for Accutech, 2002
             Some material excerpted without permission from Microsoft, Oracle courseware
                          The Aperture Grid

Dot-trio Shadow Mask
  A thin sheet of perforated metal in front of the
   screen. Each hole represents a single pixel.
Aperture-grille
  A grid of wires between the screen and the
   electron guns. A Slot-mask uses a shadow
   mask with long and thin openings rather
   than dots.

                                         Presented by Phillip Schein for Accutech, 2002
         Some material excerpted without permission from Microsoft, Oracle courseware
                                                   Terminology
Trinitron vs Invar – slotted aperture grill vs dot
Multisync – adapts scan rates automatically
Dot pitch – image quality
Dot size – determines max resolution
Color depth – number of bits per color;
  2^4 16 color base VGA
  2^8 256 color mode; 2^24 True color
Scanning:
  Non-interlaced vs interlaced
  Aspect ratio – 4:3
  Vertical (refresh) frequency –75 Hertz ( no flicker)
  Horizontal scan rate –Higher resolution, higher KHz

                                           Presented by Phillip Schein for Accutech, 2002
           Some material excerpted without permission from Microsoft, Oracle courseware
                                Presented by Phillip Schein for Accutech, 2002
Some material excerpted without permission from Microsoft, Oracle courseware
                                                             Modems
Modem – Modulation-Demodulation
UART 16550a – converts “bussed” data into a serial bit stream.
Internal vs external modems – using COM2; externals have power
   source and external LEDs but no UART
DTE/DCE
   Data Terminal /Data Circuit (communication) Equipment
RJ-11/14 (telephone jack) connectors
Dual-tone Multi-frequency (DTMF) dialing signals - the “touch-
  tone” frequencies used to “call” the far side.
Hayes AT Command Set (de facto) - control and data modes
Result code refers to number or verbose text messages the modem in
  control mode will generate upon processing a command string
RS-232 protocol – the inter-device communications are conducted
DSVD – dual simultaneous voice and data using, in addition to
  modem, a sound card, microphone, and speakers.


                                             Presented by Phillip Schein for Accutech, 2002
             Some material excerpted without permission from Microsoft, Oracle courseware
                              Modem Processes
Data is translated from parallel to serial and back again. Serial
  data is converted to an analog signal, then typically placed on a
  plain old telephone system, POTS. The data flow is
  controlled by the modem modulator circuitry and UART
  16550a. A second RJ connector is often provided to check the
  line status.
The POTS interface passes data to a demodulator on the far side
  of the connection. After demodulation, the serial data is passed
  to the far side UART which converts serial bits to parallel
  “words” that are placed on the far side expansion bus.
DTMF signals “address” the far side modem. The incoming ring
  alerts the UART to negotiate a connection. A PC or modem
  speaker supports the sound of dialtone and handshaking squeal.
The controller circuitry mediates BOTH control and data
  operations. Default and permanent settings are stored in
  NVRAM

                                           Presented by Phillip Schein for Accutech, 2002
           Some material excerpted without permission from Microsoft, Oracle courseware
                                   Modem Negotiation
Communications begin when application software attempts to
    establish a connection.
Software (DTE) signals at a COM port for a connection; UART
    asserts DTR
Modem (DCE) responds with DSR.
Serial port receives DSR and tells software to proceed with data.
    BOTH DTR and DSR are high.
Software sends init string thru COM port to DCE.
In command mode, modem goes “off hook”, dials, and “rings”.
When far (remote) side picks up, near side sends carrier tone, far side
    detects carrier tone, it returns higher pitch. Near (local) side
    responds with CD and negotiates parameters.
DTE sends RTS to DCE; DCE answers DTE with CTS. DCE uses
    CTS for flow control. When software is finished, DTR goes down.
Remote modem communicates by dropping carrier signal; local DCE
    detects loss of carrier (Dropped Carrier).
                                               Presented by Phillip Schein for Accutech, 2002
               Some material excerpted without permission from Microsoft, Oracle courseware
                          Datacom Interface




D   D                            D                               D
T   C            Protocol        C                               T
E   E       Transmission Channel E                               E


        Software that
    enables communication
                                    Presented by Phillip Schein for Accutech, 2002
    Some material excerpted without permission from Microsoft, Oracle courseware
                         Signal modulation
In the beginning, each analog signal, called a
   baud carried digital information in the form of
   bits. Baud rate was equal to the transmission
   rate of one bit on one baud (bps or bits/sec).
   Newer encoding schemes send multiple bits on
   every signal transition or baud. Baud rate is
   no longer equivalent to bps.
Encoding is different from data compression.
   The latter replaces repeating sequences with
   symbols or tokens to convey the data.


                                         Presented by Phillip Schein for Accutech, 2002
         Some material excerpted without permission from Microsoft, Oracle courseware
                                             Terminology
Three characteristics of a sinusoidal waveform:
  amplitude, frequency, and phase. Each can
  represent one bit.
Amplitude, measured in V, is how far above or
  below the zero axis a wave travels.
Frequency, measured in Hz, is the number of
  times the wave is repeated in a given period of
  time.
Phase, measured in degrees, is positioning based
  on time to travel 25, 50, or 75% of a wave.


                                          Presented by Phillip Schein for Accutech, 2002
          Some material excerpted without permission from Microsoft, Oracle courseware
                                   MNP Standards

Microcom Networking Protocol (MNP)
  A standards set composed of 10 class
  designations; for error correction and data
  compression rather than data transfer.
Both DCEs must support MNP. Standard is
  hierarchical with more advanced classes adding
  to and improving features of earlier classes and
  therefore backward compatible. For example,
  MNP Class 10 is a more powerful version of
  MNP class 4.
                                          Presented by Phillip Schein for Accutech, 2002
          Some material excerpted without permission from Microsoft, Oracle courseware
      Communication Standards
Bell Standards up to 1200 bps – obsolete
International Telecommunications Union (ITU)
   (formerly CCITT) Standards characterized by V.xxx
   which, like RS –232, refers to a standard. Bis is second
   version, ter or terbo refers to third version.
V.42 only ITU error correcting procedure for V.22, V.32
   and related versions. Link Access Procedure for
   Modems (LAPM). Degrades to MNP4.
V.42 bis combines Lempel-Ziv compression (cf. PKZIP)
   with V.42 LAPM. Thus, a 14.4 Kbps modem can
   transmit 57,600 bps using this standard.
V.92 is standard for 56 Kbps; has a 48 Kbps upstream.

                                            Presented by Phillip Schein for Accutech, 2002
            Some material excerpted without permission from Microsoft, Oracle courseware
            File Transfer Protocols
In addition to data transfer and compression
   protocols, data “packaging” is not defined by
   ITU or MNP. Modems pass bits NOT files.
Communication software located on the DTE
   provides file transfer protocols; they pass files
   not bytes or bits.
Examples are Xmodem, Ymodem, Zmodem
   (with recovery features and a 16-bit CRC), and
   Kermit (for accessing mainframes).

                                           Presented by Phillip Schein for Accutech, 2002
           Some material excerpted without permission from Microsoft, Oracle courseware
                     A modem punchlist
 Confirm operation of telecommunication resources.
 Confirm cabling and power
 Verify system resource allocations including CMOS
  settings for integrated devices
 Confirm software settings such as an AT command
  string used during initialization.
 Confirm modem operation for damage from electrical
  transients and faulty surge suppression
 Configure the modem command processor in echo
  mode (ATE1) using ATZ to reset the device and
  AT&F to restore factory defaults.


                                         Presented by Phillip Schein for Accutech, 2002
         Some material excerpted without permission from Microsoft, Oracle courseware
    AT (ATtention) Command Set
 All begin with AT hence AT commands; strings up to 40 characters
      long. Also other subsets like AT”&” and AT”%” commands.
      Programmable information can be written to modem memory
          locations (S registers); contents is stored in NVRAM


                                ATZE1Q0V1
Attention                                                         AT
reset to power-on defaults                                        Z
enable echo mode                                                  E1
Send result codes to DTE                                          Q0
Use Verbose translations                                          V1
Result code
  OK (0), CONNECT(1), RING (2), NO CARRIER(3), ERROR(4),
  NO DIAL TONE(6), BUSY(7)

                                             Presented by Phillip Schein for Accutech, 2002
             Some material excerpted without permission from Microsoft, Oracle courseware
      A init (or command) string
This initialization (init) string is passed to the modem
  during power up by communication software. Always
  a continuous “line” of characters

                ATS0=0&B1&H1&W

       Do not answer incoming calls S0=0
       Use CTS flow control         &B1
       Use a fixed DTE rate         &H1
       Store parameters in NVRAM &W


                                           Presented by Phillip Schein for Accutech, 2002
           Some material excerpted without permission from Microsoft, Oracle courseware
                       Communication Issues
 Modem settings (such as 8 data bits, no parity, 1 stop bit) must
  agree for inter-modem communication.
 Replace all (legacy) UARTs that are NOT 16550A.
 Line noise and transmit and receive levels
 System processor limitations are issues with WinModem devices.
 Disable call waiting feature (*70 on most local phone). Set S10 to
  a higher value to tolerate longer carrier signal loss to avoid
  dropping the connection.
 Automatic timeout will drop an inactive line after a specified
  period.
 System lock up can occur when one of the DTE has been “flowed
  off”, the flow control character has been sent. Check these
  settings for differences between the two modems.
 Modem initialization strings must be correct to utilize all DCE
  features.


                                            Presented by Phillip Schein for Accutech, 2002
            Some material excerpted without permission from Microsoft, Oracle courseware
    Analog Loopback Self-Test



    D                                                     D             D
D                        Protocol
    C                                                     C             T
T
    E                                                     E             E
E




                                        Presented by Phillip Schein for Accutech, 2002
        Some material excerpted without permission from Microsoft, Oracle courseware
                  Analog Loopback Test



    D                                                     D             D
D                        Protocol
    C                                                     C             T
T
    E                                                     E             E
E




                                        Presented by Phillip Schein for Accutech, 2002
        Some material excerpted without permission from Microsoft, Oracle courseware
                                Presented by Phillip Schein for Accutech, 2002
Some material excerpted without permission from Microsoft, Oracle courseware

				
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