Chapter 4 system unit components
September 8, 2016. Thursday 
(part 2)

Memory

•       Flash memory can be erased electronically and rewritten

–      CMOS technology provides high speeds and consumes little power

How a portable media player might store music in flash memory

•       Access time is the amount of time it takes the processor to read from memory

–      Measured in nanoseconds

Expansion Slots and Adapter Cards

•       An expansion slot is a socket on the motherboard that can hold an adapter card

•       An adapter card enhances functions of a component of the system unit and/or provides connections to peripherals

–      Sound card and video card

•       With Plug and Play, the computer automatically can configure adapter cards and other peripherals as you install them

•       Removable flash memory includes:

–      Memory cards, USB flash drives, and PC Cards/ExpressCard modules

Ports and Connectors

•       On a notebook computer, the ports are on the back, front, and/or sides

•       A USB port can connect up to 127 different peripherals together with a single connector

•       You can attach multiple peripherals using a single USB port with a USB hub

•       Other types of ports include:

  -Firewire port

  -Bluetooth port

  -SCSI port

  -eSATA port 

  -IrDA port

  -Serial port

  -MIDI port

•       A Bluetooth wireless port adapter converts a USB port into a Bluetooth port

•       A smart phone might communicate with a notebook computer using an IrDA port

•       A port replicator is an external device that provides connections to peripherals through ports built into the device

•       A docking station is an external device that attaches to a mobile computer or device

Buses

•       A bus allows the various devices both inside and attached to the system unit to communicate with each other

–      Data bus

–      Address bus

•       Word size is the number of bits the processor can interpret and execute at a given time

•       Expansion slots connect to expansion buses

•       Common types of expansion buses include:

  -PCI bus

  -PCI Express bus 

  -Accelerated Graphics Port

  -USB and FireWire bus

  -PC Card bus

  

•       A bay is an opening inside the system unit in which you can install additional equipment

–      A drive bay typically holds disk drives

Power Supply

Putting It All Together

Keeping Your Computer
or Mobile Device Clean

Differentiate the following:

A)DSL

-A domain-specific language (DSL) is a computer language specialized to a particular    application domain.

A domain-specific language is created specifically to solve problems in a particular domain and is not intended to be able to solve problems outside it (although that may be technically possible). In contrast, general-purpose languages are created to solve problems in many domains. The domain can also be a business area. Some examples of business areas include:

·domain-specific language for life insurance policies developed internally      in large insurance enterprise

·domain-specific language for combat simulation

·domain-specific language for salary calculation

·domain-specific language for billing

Examples of domain-specific languages include HTML, Logo for pencil-like drawing, Verilog and VHDL hardware description languages, MATLAB and GNU Octavefor matrix programming, Mathematica, Maple and Maxima for symbolic mathematics, Specification and Description Language for reactive and distributed systems,spreadsheet formulas and macros, SQL for relational database queries, YACC grammars for creating parsers, regular expressions for specifying lexers, the Generic Eclipse Modeling System for creating diagramming languages, Csound for sound and music synthesis, and the input languages of GraphViz and GrGen, software packages used for graph layout and graph rewriting.

B)Fiber to the premises (FTTP)

Fiber to the premises (FTTP) is a form of fiber-optic communication delivery, in which an optical fiber is run in an optical distribution network from the central office all the way to the premises occupied by the subscriber. The term "FTTP" has become ambiguous and may also refer to FTTC where the fiber terminates at a utility pole without reaching the premises.

Fiber to the premises can be categorized according to where the optical fiber ends:

·  FTTH (fiber-to-the-home) is a form of fiber-optic communication delivery that reaches one living or working space. The fiber extends from the central office to the subscriber's living or working space. Once at the subscriber's living or working space, the signal may be conveyed throughout the space using any means, including twisted pair, coaxial cable, wireless, power line communication, or optical fiber.

·  FTTB (fiber-to-the-building or -basement) is a form of fiber-optic communication delivery that necessarily applies only to those properties that contain multiple living or working spaces. The optical fiber terminates before actually reaching the subscribers living or working space itself, but does extend to the property containing that living or working space. The signal is conveyed the final distance using any non-optical means, including twisted pair, coaxial cable, wireless, orpower line communication.

      An apartment building may provide an example of the distinction between FTTH and FTTB. If a fiber is run to a panel inside each subscriber's apartment unit, it is FTTH. If instead the fiber goes only as far as the apartment building's shared electrical room (either only to the ground floor or to each floor), it is FTTB.

C)Fixed wireless

-Fixed wireless is the operation of wireless devices or systems used to connect two fixed  locations (e.g., building to building or tower to building) with a radio or other wireless link, such  as laser bridge.[1] Usually, fixed wireless is part of a wireless LAN infrastructure. The purpose of  a fixed wireless link is to enable data communications between the two sites or buildings. Fixed  wireless data (FWD) links are often a cost-effective alternative to leasing fiber or installing cables  between the buildings.

-The point-to-point signal transmissions occur through the air over  a terrestrial microwave platform rather than through copper or optical fiber; therefore, fixed  wireless does not require satellite feeds or local telephone service. The advantages of fixed  wireless include the ability to connect with users in remote areas without the need for laying new  cables and the capacity for broad bandwidth that is not impeded by fiber or cable capacities.  Fixed wireless devices usually derives their electrical power from the public utility mains, unlike  mobile wireless or portable wireless devices which tend to be battery powered.

D)Cellular radio network

A cellular network or mobile network is a communication network where the last link is wireless. The network is distributed over land areas called cells, each served by at least one fixed-location transceiver, known as a cell site or base station. This base station provides the cell with the network coverage which can be used for transmission of voice, data and others. A cell might use a different set of frequencies from neighboring cells, to avoid interference and provide guaranteed service quality within each cell.

Cellular networks offer a number of desirable features:

·  More capacity than a single large transmitter, since the same frequency      can be used for multiple links as long as they are in different cells

·  Mobile devices use less power than with a single transmitter or satellite      since the cell towers are closer

·  Larger coverage area than a single terrestrial transmitter, since                additional cell towers can be added indefinitely and are not limited by      the horizon

E)WI-FI

Wi-Fi or WiFi is a technology that allows electronic devices to connect to a wireless LAN (WLAN) network, mainly using the 2.4 gigahertz (12 cm) UHF and 5 gigahertz (6 cm) SHF ISM radio bands. A WLAN is usually password protected, but may be open, which allows any device within its range to access the resources of the WLAN network.

The Wi-Fi Alliance defines Wi-Fi as any "wireless local area network" (WLAN) product based on the Institute of Electrical and Electronics Engineers' (IEEE) 802.11 standards.However, the term "Wi-Fi" is used in general English as a synonym for "WLAN" since most modern WLANs are based on these standards. "Wi-Fi" is a trademark of the Wi-Fi Alliance. The "Wi-Fi Certified" trademark can only be used by Wi-Fi products that successfully complete Wi-Fi Alliance interoperability certification testing.

F)Satellite Internet service

Satellite Internet access is Internet access provided through communications satellites. Modern consumer grade satellite Internet service is typically provided to individual users through geostationary satellites that can offer relatively high data speeds,with newer satellites using Ka band to achieve downstream data speeds up to 50 Mbps.