Kernels and Routines

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Kernels and Routines

• Dr. Harold D. Camp
• IT 212 002
• 29 March 2007

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Homework 6

• For an application that maintains your checkbook,
  build three flow charts
• Kernel flow chart showing the process of
  balancing a check book
• Routine flow chart showing the accessing of data
  from a hard drive (that is called from the Kernel)

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Flow Charting
Call Routine
Function
Decision
Start/Stop
Input or Output
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Sample Flow Diagram
Start/Stop
OS Supplied Routines
Read Balance, Type, Amount
If Type Is Debit
Kernel
Call Debit
Call Credit
Kernel Specific Routines
Stop
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Sample Flow Diagram
Debit
Start/Stop
NBal Bal - Amt
Read Balance, Type, Amount
If NBal gt 0
Call Dispense
If Type Is Debit
Call Debit
Write NBal
Call Reject
Call Credit
Return
Stop
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So, Check Book Kernel

• Checkbook Activities
• Debit
• Credit
• Balance
• Does my balance agree with Banks balance?
• Routines (One Kernel Specific and One OS
  Required)
• DLL
• API
• Registry

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Dynamic Link Library (DLL)

• A library of executable functions or data that
  can be used by a Windows application
• A DLL provides one or more functions
• A program accesses the functions by creating a
  static or a dynamic link to the DLL
• A static link remains constant during program
  execution
• A dynamic link is created by the program as
  needed
• A DLL can be used by several applications at the
  same time
• Some DLLs are provided with the Windows operating
  system and available for any Windows application
• Other DLLs are written for a particular
  application and are loaded with the application

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Dynamic Link Library (DLL)

• DLL is Microsoft's implementation of the shared
  library concept in the Microsoft Windows and OS/2
  operating systems
• Usually have the file extension DLL, OCX (for
  libraries containing ActiveX controls), or DRV
  (for legacy system drivers)
• DLL file formats are the same as for Windows EXE
  files
• Portable Executable (PE) for 32-bit Windows
• New Executable (NE) for 16-bit Windows
• DLLs can contain code, data, and resources, in
  any combination.

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Dynamic Link Library (DLL)
http//www.eldos.com/documentation/solfs/dll_funct
ions_list.html
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Application Program Interface (API)

• A set of routines, protocols, and tools for
  building software applications
• A good API makes it easier to develop a program
  by providing all the building blocks
• A programmer puts the blocks together
• Most operating environments, such as MS-Windows,
  provide an API
• Programmers can write applications consistent
  with the operating environment
• Guarantee that all programs using a common API
  will have similar interfaces
• Examples?

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Registry

• A database used by the Windows operating system
  to store configuration information
• The Registry consists of the following major
  sections
• Roots - file associations and OLE information
• Users Preferences - all preferences set for
  current user
• User Information - all the current user
  information for each user of the system
• Local Machine Settings - settings for hardware,
  operating system, and installed applications
• Current Configuration - settings for the display
  and printers and other devices
• Dynamic Data - performance data
• Most Windows applications write data to the
  Registry
• You can edit the Registry directly by using the
  Registry Editor
• regedit.exe provided with the operating system
• Errors in the Registry could disable your
  computer.

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In Class Example

• Digital Clock Kernel
• Kernel Specific Routines
• OS Specific Routines
• Be careful here
• Must use API, DLL, Registry

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Bandwidth and Moving Data,A/D Converters, UPS,
Ports, SATA, USB
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How Bandwidth Moves Data

• In Class Discussion

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Analog to Digital Converters

• Signals in the real world are analog
• Light, sound, you name it
• Must be converted into digital, using a circuit
  called ADC (Analog-to-Digital Converter), before
  they can be manipulated by digital equipment

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Analog to Digital Converters

• Signals in the real world are analog
• Light, sound, you name it
• Must be converted into digital, using a circuit
  called ADC (Analog-to-Digital Converter), before
  they can be manipulated by digital equipment

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Digital to Analog Conversion
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Analog to Digital Converters

• In Class Discussion
• http//electronics.howstuffworks.com/analog-digita
  l4.htm

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Uninterruptable Power Supplies

• http//www.aeceuro.co.uk/upsAnimation.asp
• Voltage surges and spikes - Times when the
  voltage on the line is greater than it should be
• Voltage sags - Times when the voltage on the line
  is less than it should be
• Total power failure - Times when a line goes down
  or a fuse blows somewhere on the grid or in the
  building
• Frequency differences - Times when the power is
  oscillating at something other than 60 Hertz

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Ports

• A port serves as an interface between the
  computer and other computers or devices
• Physically, a port is a specialized outlet to
  which a plug or cable connects
• Serial ports send and receive one bit at a time
  via a single wire pair (Ground and /-)
• Parallel ports send multiple bits at the same
  time over several sets of wires

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Ports

• After ports are connected, they typically require
  "handshaking,"
• similar to negotiation, where transfer type,
  transfer rate, and other necessary information is
  shared before data are sent
• Hot-pluggable ports can be connected while
  equipment is running
• Hot-plugging a keyboard on many computer models
  can cause permanent damage to the motherboard
• Plug-and-play ports are designed so that the
  connected devices automatically start handshaking
  as soon as the hot-plugging is done
• USB ports and FireWire ports are plug-and-play
• At times, special software (driver) must be
  loaded to allow communication (correct signals)
  for certain devices
• A driver doesn't change the port,
• Rather a driver uses the port signal to control
  the attached device

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Ports

• Currently (2006) manufacturers have nearly
  standardized on colors associated with ports on
  personal computers, although there are no
  guarantees. The following is a short list
• Orange, purple, or Grey Keyboard PS/2
• Green Mouse PS/2
• Blue or magenta Parallel Printer DB-25
• Amber Serial DB-25 or DB-9
• Pastel pink Microphone 1/4" stereo (TSR)
  Minijack
• Pastel green Speaker 1/4" stereo (TSR) Minijack

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Ports
http//www.cyberwalker.net/connectors
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Serial Advanced Technology Attachment (SATA)

• SATA
• A computer bus technology primarily designed for
  transfer of data to and from hard disks and
  optical drives
• Designed as a successor to the legacy Advanced
  Technology Attachment standard (ATA)
• Expected to replace the older Parallel ATA
  technology
• Serial ATA adapters and devices communicate over
  a high-speed serial link
• Architecture
• Two pairs of (unidirectional) signal wires
• Low Voltage Differential Signaling (LVDS)
• 1.5 Gbit/s and up
• Above the SATA physical level are the link level
  and transport level
• Convert data into discrete ordered packets
• The application level generates read/write PIO
  and DMA requests
• Each SATA/device has a link to a SATA host-port,
  with no sharing of cable or bandwidth between
  devices

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Serial Advanced Technology Attachment (SATA)
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Universal Serial Bus

• A serial bus standard to interface devices
• Designed for personal computers
• Has become commonplace on handheld devices
• Devised to help retire all serial and parallel
  ports on personal computers
• A USB system has an asymmetric design
• Host controller
• Multiple daisy-chained peripheral devices
• Additional USB hubs may be included in the chain
• Allows branching into a tree structure, subject
  to a limit of 5 levels of branching per
  controller
• No more than 127 devices
• USB's ability to daisy-chain devices
• Led to computers shipped only two USB ports
• To reduce the need for USB hubs, desktop
  computers now come with more USB ports
• Up to half of them on the front panel to
  facilitate temporary connection of portable
  devices

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Universal Serial Bus

• USB designed to allow peripherals to be connected
  without expansion cards
• And to improve plug-and-play capabilities by
  allowing devices to be hot-swapped
• Connected or disconnected without powering down
  or rebooting the computer
• When a device is first connected, the host
  enumerates and recognizes it, and loads the
  device driver it needs
• USB can connect peripherals
• Such as mouse devices, keyboards, PDAs, gamepads
  and joysticks, scanners, digital cameras,
  printers, external storage, networking
  components, etc.
• For many devices such as scanners and digital
  cameras, USB has become the standard connection
  method
• USB is also used extensively to connect
  non-networked printers, replacing the parallel
  ports that had previously been in wide use

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Universal Serial Bus Features

• The computer acts as the host.
• Up to 127 devices can connect to the host, either
  directly or by way of USB hubs.
• Individual USB cables can run as long as 5
  meters with hubs, devices can be up to 30 meters
  (six cables' worth) away from the host.
• With USB 2.,the bus has a maximum data rate of
  480 megabits per second.
• A USB cable has two wires for power (5 volts and
  ground) and a twisted pair of wires to carry the
  data.
• On the power wires, the computer can supply up to
  500 milliamps of power at 5 volts.
• Low-power devices (such as mice) can draw their
  power directly from the bus. High-power devices
  (such as printers) have their own power supplies
  and draw minimal power from the bus. Hubs can
  have their own power supplies to provide power to
  devices connected to the hub.
• USB devices are hot-swappable, meaning you can
  plug them into the bus and unplug them any time.
• Many USB devices can be put to sleep by the host
  computer when the computer enters a power-saving
  mode.
• http//computer.howstuffworks.com/usb.htm

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