◄Unit 1: COMPUTER FUNDAMENTALSTopic 3►

Unit 2: Computer Architecture and ambassy

  • Unit 2: Computer Architecture and ambassy

    Key Unit Competency

    By the end of the unit, you should be able to:
    • Identify computer components and their functions (input, output, processing and
    storage.
    • Assemble, disassemble computers and perform basic maintenance services.

    Unit Outline

    • Computer system.
    • Computer hardware.
    • Audio port and connector.
    • Internal computer components.
    • Assembling computers.
    • Cleaning and disposing of computer components.
    I    ntroduction
    his unit introduces us to computer components and their functionality in order
    to have a common understanding of microcomputers regardless of their physical
    configuration. later the unit focuses on fundamentals of computers architecture that 
    aims at equipping us with practical skills on how to assemble, disassemble, and repair

    desktop computers. 

    2.4 Computer system 

    Thought there are various definitions of computer systems , in our context we define a
    computer system as the combination of hardware, software (programs), user (liveware)
    and data that forms a complete, working system.
    2.1.1 User 
    A computer system is not complete without people referred to as users or liveware.
    Although some types of computers can operate without much intervention from users,
    most personal computers are designed specially for use by people. 
    2.1.2  Hardware 
    In computer science  context, hardware refers to physical components  that makes up 
    a computer system. Common examples of hardware include system unit , keyboard ,
    mouse, monitor, printer, speakers and modem.
    2.1.3 Software
    The term software refers to a set of instructions also known as program that directs a
    computer what to do. Some programs operates computer hardware and other programs
    while others enable  a computer user to perform specific tasks such as accounting. 
    2.1.4 Data
    Data consists of raw facts which the computer can manipulate and process into
    information that is useful to the user. In digital computers, data is converted from
    forms that people can understand such as text, numerals, sounds, and image into 
    binary digit zeros and ones.
    The four components that make up a computer system are illustrated in Fig. 2.1. Note
    that the software component is represented by shelved software casings and programs
    running in the computer, while data is illustrated by information on the screen and
    on a piece of paper on the desk.

     

    

    

    2.2 Computer functions
    Computers manipulate (process) data (input) to produce information (output) and

    hold (store) processed information for future use as shown in Fig. 2.2.

     



    . In put: The first box on the illustration depicts 
    • Process: The computer then performs processing such as calculations and
    comparisons.
    • Output: The computer generates information that may be printed or displayed on
    a screen or in a specified format.
    • Storage: Data and information may be stored for future use on storage devices
    such as hard disk, CD/DVD etc.

    2.3 Computer hardware
    Generally the main hardware components of a typical desktop computer can be

    Classified into two broad categories namely ; peripheral devices as the system unit.

    2.3.1 Peripheral Devices

    Most desktop computers consist of external devices connected to a central housing 
    Known as the system unit . collectively external  input devices such as keyboard and  
    output devices such as the monitor are referred to as peripheral devices. Fig. 2.3

    shows common examples of peripheral devices                                                                                                                                                                                          

       

    2.3.2 Computer case 

    The computer case, commonly referred to as the system unit, is the main
    hardware part in which internal  components such as microprocessor, computer
    memory, and drives are housed . In terms of physical appearance (form factor)
    the two common types of system units re tower type shown in Fig .2.4 (a)
    and desktop type in Fig .2.4 (b) .The main difference is that, in tower system unit 
    the monitor rests on the table while in desktop types; the monitor may be
    replaced on top of the system unit.

     


    2.3.2 Computer case          

        The computer case                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      

    2.3.3 Ports and connectors

    A port is a physical or wireless interface between the computer and peripheral devices.
    Physically, you can identify ports such as shown in Fig. 2.5 through which devices
    may be connected using interface cables. In this section, we discuss ports such as
    serial, parallel, universal serial bus (USB), Ps/2, HDMI and VGA shown in Fig. 2.5
    (a) and (b).



    2.3.3.1  Serial port

    Serial ports also known as RS232 ports are used to connect devices that transmit
    and receive data as a series of binary digits (bits). Although RS232 ports and cable
    shown in Fig. 2.6 have become obsolete, they were used to connect devices such as
    the mouse, serial modems and printers.




    2.3.3.2 Parallel Port

    A parallel port is an interface used to connect devices that transmit and receive
    multiple bits simultaneously (in parallel) hence it is faster than the serial interface.
    To connect devices such as printers and scanners to a parallel port, we use a 25-pin
    parallel cable also referred to as DB-25 shown in Fig. 2.7

    2.3.3.3 Universal Serial Bus
    Universal serial bus (USB)  is industry standard  interface that defines cables, 
    connectors and protocols for connections between computers and peripheral devices.
    Universal Serial Bus (USB)  is the high-speed  serial port that  has become the standard 
    interface hence replacing most serial and parallel ports. It is now common to find USB ports on most 
     electronic devices such as tablets, radios, TVs, mobile phones, and set top boxes . on of the reasons
    of the USB interface has become popular is because as many as 127 devices can be
     daisy chained and connected to a single port using USB cable such as the one shown in Fig. 2.8.





    3.3.4 Personal System/2 ports
    Previously, most computers came with a pair of Personal Systems 2 (PS/2) ports also
    known as mini-DIN. However, most computer manufacturers have phased out PS/2
    ports in favour of USB interfaces and wireless connectivity. Fig. 2.9 shows a closer
    look of the PS/2 ports the one coded in pink to connect a keyboard while the green
    ports is used connects a mouse. 




    2.3.3.5 Video graphics array port

    A Video Graphics Array (VGA) port is a D-shaped interface used to connect display 
    devices such  as TVs , monitor or LCD projectors  to the computer. Fig 2.10  shows an
    illustration of  a 15 -pin  VGA  cable used to connect monitor or projectors  to a computer. 





    2.3.3.6  Audio ports

    Most computers and mobile devices come with audio interface used to connect
    speakers, microphones (mic) and other audio devices. Fig. 2.11(a) shows three audio
    ports  while fig .2 11 (b) shows output (speaker) and in put (microphone) jacks coded 
    in green and pink colors.







    2.3.3.7 Network port

    Network interface is a port that connects a device to physical or wireless transmission
    media in computer network. Most computers today come with a network interface
    known as RJ45 shown on fig 2.12 (b) to which transmission  media with RJ45 
    connector shown in Fig . 2.12 (b) is plugged to establish a connection.
     




    2.3.3.8 Firewire connector
    Firewire port also referred to as IEEE 1394 is almost similar to USB but has higher
    data transmission rate. Therefore ,  firewire is suitable for streaming video from digital 
    cameras to a computer. Fig. 2.13(a) shows an illustration of Firewire port while Fig.
    2.13( b ) shows the two ends of the firewire cable connectors. 

    2.3.3. 9 High definition multimedia  interface 
    High Definition Multimedia Interface (HDMI) is a interface for transferring 
    compressed and uncompressed digital audio or video data from HDMI compliant 
    device to a computer, projector, digital TV or audio device. HDMI is intended to be a
    replacement for analog video standards such as the VGA.






    2.3.3.10 Small Computer Systems Interface

    Small Computer Systems Interface (SCSI) is a set of parallel interface standards
    defined by ANSI for attaching peripheral devices such as printers ,disk drives ,tape
    drives and scanners. Although SCSI port shown in Fig. 2.15 is available on some
    devices, it has become obsolete in favour of USB, Firewire, HDMI and wireless
    standards. 






    2.4 Internal Computer Components
    We have already learnt about various peripheral devices and how they are connected to
    the system unit through ports. In this section, we discuss the main components found
    inside the system unit such as disk drives, motherboard, processor and memory. But,
    before we open the system unit cover, it is important that you observe the following
    safety precautions:
    1. Always disconnect the computer from power source before starting to work on
    them.
    2. Do not work on any peripheral device without the guidance of the tutor or
    laboratory technician
    3. Never work in isolation because you may need help in case of any emergency.
    4. Always discharge static electricity that might have built up on the body by touching
    an earthed metallic object or weaning  antistatic wrist member.





    2. Observe and identify various components inside the system unit.
    2.4.1 Power supply unit and connectors
    The Power Supply Unit (PSU) shown in Fig. 2.17 converts alternating current (AC) from mains to direct current (DC) required by internal computer components. The current supplied to the internal components like motherboard, hard disk, and optical drives depends on the rating from the device manufacturer. Note that unlike desktop 
    computer that are fitted with PSU, portable computers like laptops come with power
    adapters that convert AC to DC.


    Types of power supply unit connectors
    The power supply unit connectors can be classified  into external and internal connectors.
    The external connectors are used  to connect the power supply unit to the power outlet
    while internal connectors are used to supply and distribute power to internal device
    Inside the computer found  inside the computer case. In the power supply unit show in
    Fig.2.17  above shows an examples of internal and external  power connectors 


    ◄Unit 1: COMPUTER FUNDAMENTALSTopic 3►