NETWORK .

 A Network is a collection of computers and devices connected together via communications devices and transmission media.
Computer communications is a process in which two or more computers or devices transfer data, instructions, and information.

Some communications involve cables and wires; others are sent wirelessly through the air.

A Network Topology refers to the layout of

the computers and devices in a

communications network.

It refers to both the physical and logical

layout of a network.

Physical Topology

The arrangement of a cabling is the physical

 topology.

Logical Topology

The path that data travels between computers

 on a network is the logical topology.

Types of Network Topologies : 

UTILITY PROGRAM

SYSTEM SOFTWARE-UTILITY PROGRAM

DEFINITION: A utility is a type of system software that allows users to perform maintenance-type task.

TYPES OF UTILITY PROGRAM:

1. FILE MANAGER

A file manager is a utility that performs functions related to the file management

* Displaying a list of file

*Copying, renaming, deleting, moving, and short files folders

    2.   DISK CLEANUP

A disk cleanup utility searches  for and removes unnecessary files

* Downloaded program files

* Deleted unused program files

     

   3.     ANTI-VIRUS PROGRAM

A virus describes a potentially damaging computer program that affects a computer negatively.

* An antivirus program that protects a computer against virus.

* Avira Antivirus, Kaspersky Antivirus, Norton Antivirus.

APPLICATION SOFTWARE

APPLICATION SOFTWARE: Consist of programs designed to make user more productive and assist with personal task.

TYPES OF SOFTWARE:

• Open source software 

* Created by unpaid volunteers, begin to gain wide acceptance

* Freely.

• Proprietary software

* Privately owned and limited to a specific vendor or computer model.

* License/ paid.

1. WEB BROWSER

Allow user with an internet connection to access and view Web pages or access programs.

Example:

• Google Chrome
• Firefox
• Opera  

TYPES OF OPERATING SYSTEM

TYPES OF OPERATING SYSTEM

• STAND-ALONE
• SERVER
• EMBEDDED/MOBILE

STAND-ALONE...

A stand alone operating system is a complete operating system that works on a desktop computer, notebook computer or mobile computing device.

• WINDOWS
• Mac OS X
• UNIX
• Linux

SERVER...

• Windows Server 2008
• UNIX
• Linux
• Solaris
• NetWare

EMBEDDED...

An embedded operating system resides on a ROM chip on a mobile device or consumer electronic device.

• Windows Embedded CE
• Windows Phone 7
• Palm OS
• iPhone OS
• Blackberry
• Google Android
• Embedded Linux
• Symbian OS

STORAGE

•Storage holds data, instructions, and information for future use

•A storage medium / media is the physical material on which a computer keeps data, instructions, and information

STORAGE CAPACITY

•Capacity is the number of bytes a storage medium

can hold

Capacity Storage Measured in 

•Kilobytes = 1,024 bytes,

•Megabytes = 1,024 Kilobytes

•Gigabytes = 1,024 Megabytes

•Terabytes = 1,024 Gigabytes

STORAGE DEVICES

•A storage device is the computer hardware that

records and/or retrieves items to and from storage

media

•To store data and programs when they are not being

processed.

•Stores files permanently.

•Available in the form of hard disk, CD, USB drive,

 etc.

TYPES OF STORAGE

•Magnetic Storage

•Optical Storage

•Flash memory

MAGNETIC STORAGE

–Uses different patterns of magnetization on a magnetically coated surface to store information.

–Examples of magnetic storage are:

       Hard Disk

       Floppy disk

HARD DISK

•A hard disk contains one or more inflexible, circular

platters that use magnetic particles to store data,

instructions, and information

•An external hard disk is a separate free-standing hard disk that connects to your computer with a

cable or wirelessly

•A removable hard disk is a hard disk that you insert and remove from a drive

•Internal and external hard disks are available in miniature sizes (miniature hard disks)

OPTICAL DISCS STORAGE

–Stores information in deformities on the surface of a

circular disc and reads this information by

illuminating the surface with a laser diode and

observing the reflection.

–Types of optical disc are:

»Compact Disc (CD)

»Digital Video Disc (DVD)

»Blu-ray Disc (BD)

•A CD-ROM can be read from but not written to

      -Read from a CD-ROM drive or CD-ROM            player

•A CD-R is a multisession optical disc on which users can write, but not erase

•A CD-RW is an erasable multisession disc

-Must have a CD-RW drive

•A DVD-ROM is a high-capacity optical disc on which users can read but not write or erase

-Requires a DVD-ROM drive

•A Blu-ray Disc-ROM (BD-ROM) has a storage capacity of 100 GB

•DVD-RW, DVD+RW, and DVD+RAM are high-capacity rewritable DVD formats

FLASH MEMORY STORAGE

•Flash memory chips are a type of solid state media and contain no moving parts

–Examples of flash memory storage are:

1) solid states drives

2) memory card

3) USB flash drives

SOLID STAES DRIVES

•Solid state drives (SSDs) have several

advantages over magnetic hard disks:

    -faster access time

    -faster transfer rates

    -generate less heat and consume less power

    -last longer

STORAGE CAPACITY DIFFERENCES TABLE

(between magnetic, optical and flash memory)

COMPARE MEMORY AND STORAGE

OPERATING SYSTEM

COMPUTER SYSTEM-OPERATING SYSTEM

DEFINITION: System software is a set of programs containing instructions that work together to coordinate all the activities among computer hardware resources.

OPERATING SYSTEM FUNCTIONS:

• Start and shut down a computer.

The process of starting or restarting a computer us called booting.

WARM BOOT** Using the operating system ti restart a computer.

COOL BOOT** Turning on a computer that has beeb powered off completely.

• Provide user interface

A user interface controls how you entered data and instructions and how information is displayed on the screen.

-->>2 types of user interface

** Graphical user interface

** Command-line

• Control a network

Some operating system are designed to work with a server in a network.

A server operating system orgenizes and coordinate how multiple users access and share resources on a network.

NON-VOLATILE MEMORY : ROM

• Read-only memory (ROM) refers to memory chips storing permanent data and instructions.
• The data on most ROM chips cannot be modified

TYPES OF ROM 

PROGRMMABLE READ-ONLY MEMORY (PRAM)

 • Is a blank ROM chip on which a programmer can write permanently.

ERASABLE READ-ONLY MEMORY  (ERAM)

•  These chips can be erased and rewritten a number of times.

ELECTRICALLY ERASABLE PROGRAMMABLE READ-ONLY MEMORY (EEPROM)

• Allows a programmer to erase the microcode with anelectric signal

VOLATILE MEMORY : RAM

•RAM chips usually reside on a memory module and are inserted into memory slot

•The amount of RAM necessary in a computer often depends on the types of software you plan to use

THREE BASIC TYPES OF RAM

DYNAMIC RAM (DRAM

•Chips must be re-energized constantly or they lose their contents.

STATIC RAM (SRAM)

• Chips are faster and more reliable than any

variation of DRAM chips.

• Are much more expensive than DRAM chips.

MAGNETORESISTIVE RAM (MRAM)

• A newer type of RAM, called magnetoresistive

RAM (MRAM pronounced EM-ram), stores data using

magnetic charges instead of electrical charges

MEMORY

   Memory consists of electronic components that store instructions waiting to be executed by the processor, data needed by those instructions, and the results of processing the data

Memory size is measured in kilobytes (KB or K),

megabytes (MB), gigabytes (GB), or terabytes (TB)

TYPES OF MEMORY

> Volatile

> Nonvolatile

   VOLATILE MEMORY

•When the computer’s power is turned off, volatile memory loses its contents.

•Volatile memory is temporary.

•RAM is the most common type of volatile memory

NONVOLATILE MEMORY

    •Nonvolatile memory does not lose its  contents when power is removed from the  computer.

•Nonvolatile memory is permanent.

•Examples of nonvolatile memory include ROM.

    Differences between volatile and non-volatile

    VOLATILE MEMORY

1) Loses its contents when power is turned       off (store data for temporary time only)

2) Can be read from and written to by the           processor and other devices.

3) Hold data or programs that are currently       being used by the processor
                         

4) RAM chip are assembled on a small             circuit board called memory module which     is plugged onto the memory slots.

NONVOLATILE MEMORY

  1)Does not lose contents when power is removed(store data permanently)

  2)Data is prerecorded for read only and cannot be modified or removed

  3)Contain a small startup program          (BIOS) which is used to boot the          computer 

 4)Exists as a chip on the motherboard