Computer Literacy Notes 3

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  • 8/11/2019 Computer Literacy Notes 3


    Syed Khateeb Ahmed Shah Computer Literacy






    Memory refers to the physical devices used to store programs (sequences of instructions) or

    data (e.g. Programstate information)on a temporary or permanent basis for use in a

    computer or otherdigitalelectronic device.

    Just like humans, computers rely a lot on memory. They need to process and store data, just

    like we do. However, computers store data indigital format, which means the information

    can always be called up exactly the way it was stored. Also, unlike our memory, the

    computer's memory doesn't get worse over time.


    It is also known as internal or main memory. Primary memory is computermemory that is

    accessed directly by theCPU.This includes several types of memory, such as the processor

    cache and systemROM.However, in most cases, primary memory refers to systemRAM.

    RAM (Random Access Memory)

    RAM, or random access memory, consists of one or morememory modules that

    temporarily store data while a computer is running. RAM is volatile memory, meaning it is

    erased when the power is turned off. As the computer loads parts of the operating system and

    drivers are loaded into memory, which allows theCPU to process the instructions much

    faster and your computer to load faster. After the operating system has loaded, each program

    you open such as the browser you're using to view this page is loaded into memory while it is

  • 8/11/2019 Computer Literacy Notes 3


    Syed Khateeb Ahmed Shah Computer Literacy


    ROM (Read Only Memory)

    ROM is memory containing hardwired instructions that the computer uses when it boots up,

    before the system software loads. In PCs, the instructions are read from a small program in

    the ROM, called the BIOS (basic input/output system).

    ROM is a type of "built-in" memory that is capable of holding data and having that data read

    from the chip, but not written to. Unlike Random Access Memory (RAM), ROM isnon-

    volatile which means it keeps its contents regardless if it has power or not.


    Alternatively referred to as external memory and secondary storage is a storage medium that

    holds information until it is deleted or overwritten regardless if the computer has power.

    Secondary memory (or secondary storage) is the slowest and cheapest form ofmemory.Itcannot be processed directly by theCPU.It must first be copied into primary storage (also

    known asRAM ).


    When you save data or install programs on your computer, the information is typically

    written to your hard disk. The hard disk is a spindle of magnetic disks, called platters, that

    record and store information. Because the data is stored magnetically, information recorded

    to the hard disk remains intact after you turn your computer off.

    A hard disk drive (HDD) is adata storage device used for storing and retrievingdigital

    information using rapidly rotating disks (platters)coated with magnetic material. An HDD

    retains its data even when powered off. Data is read in arandom-access manner, meaning

    individualblocks of data can be stored or retrieved in any order rather thansequentially.An

    HDD consists of one or more rigid ("hard") rapidly rotating disks (platters)withmagnetic

    heads arranged on a movingactuator arm to read and write data to the surfaces.
  • 8/11/2019 Computer Literacy Notes 3


    Syed Khateeb Ahmed Shah Computer Literacy


    CD ROM/ RW

    Stands for "compact disc read-only memory." a CD-ROM is a CD that can be read by a

    computer with an optical drive. The "ROM" part of the term means the data on the disc is

    "read-only," or cannot be altered or erased. The first CD-ROMs could hold about 600 mb of

    data, but now they can hold up to 700 mb. CD-ROMs share the same technology as audio

    CDs, but they are formatted differently, allowing them to store many types of data.

    A CD-RW (compact disc-rewritable) is a rewritableoptical disc.It was introduced in 1997,

    and was known as "CD-writable" during development.


    Flash drives have many names jump drives, thumb drives, pen drives, and USB keychain

    drives. Regardless of what you call them, they all refer to the same thing, which is a small

    datastorage device that usesflash memory and has a built-inUSB connection.

    Flash drives are typically no more than two to three inches in length and less than an inch inwidth. Their size and shape may resemble a thumb or a small pen (which is where the names

    "thumb drive" and "pen drive" come from).

    A USB flash drive is adata storage device that includesflash memory with an integrated

    Universal Serial Bus (USB) interface. USB flash drives are typically removable and

    rewritable, and physically much smaller than anoptical disc.Most weigh less than 30 grams

    (1.1 oz). As of January 2013, drives of up to 512gigabytes (GB) are available.

    Memory is measured in term of bits and bytes.

    8 bits = 1 byte

    1000 bytes = 1 Kilobyte1000 kilobytes = 1 Megabyte
  • 8/11/2019 Computer Literacy Notes 3


    Syed Khateeb Ahmed Shah Computer Literacy


    1000 megabytes = 1 Gigabyte

    1000 gigabytes = 1 Terabyte


    Computer hardware is the collection of physical elements that constitute acomputer system.

    Computer hardware refers to the physical parts or components of a computer such as monitor,

    keyboard, computer data storage, hard drive disk, mouse, system unit (graphic cards, sound

    cards, memory, motherboard and chips), etc. All of which are physical objects that you can

    actually touch.


    Software is untouchable. Software exists as ideas, application, concepts, and symbols, but it

    has no substance. A combination of hardware and software forms a usable computing system.

    Software is a general term. It can refer to all computer instructions in general, or to any

    specific set of computer instructions.

    Computer software is a set of programs, procedures, functions, associated data and/or its

    documentation, if any.
  • 8/11/2019 Computer Literacy Notes 3


    Syed Khateeb Ahmed Shah Computer Literacy





    System software is a program that manages and supports the computer resources and

    operations of a computer system while it executes various tasks such as processing data andinformation, controlling hardware components, and allowing users to use different programs.


    Application software consists of programs that direct computers to perform specific

    information processing activities for end users. These programs are called application

    packages because they direct the processing required for a particular use, or application,

    which users want to accomplish. Thousands of application packages are available because

    there are thousands of different jobs end users want computers to do.


    Utility software is a part ofsystem software designed to help analyze, configure, optimize or

    maintain a computer. Utility software usually focuses on howthe computer infrastructure
  • 8/11/2019 Computer Literacy Notes 3


    Syed Khateeb Ahmed Shah Computer Literacy


    (including thecomputer hardware,operating system,application software anddata storage)

    operates. Due to this focus, utilities are often rather technical and targeted at people with an

    advanced level of computer knowledge.