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Beginner Lessons

Microsoft Windows XP Starter Edition

Lesson 3: Computer Storage and Maintenance

Objectives

At the end of this lesson, you will understand:

Skills You Will Need

Before you learn the stated objectives, you should be familiar with:

  • The advantages of computers as covered in Lesson 1
  • The characteristics of input, output, and input/output devices discussed in Lesson 2

Session 1: Storage Devices

Computer storage refers to the data stored in an electromagnetic form to be used by the processor. You can measure the amount of data stored on a computer just as you can measure the amount of water in a container, although the measurement units are different, of course. The storage capacity defines the amount of data that can be stored on a storage device.

Computer Data

A computer stores a variety of data and information in its memory, including numbers (0-9), letters (A-Z), and symbols and other characters (#, {}, ', ~, ^). A computer uses the binary system to represent these characters. In a binary system, only two digits — 0 and 1 — are used. The 0s and 1s in the binary system are known as bits (binary digits). A bit is the smallest unit of measurement of storage capacity. A set of eight bits is called a byte.

Note  Kilobytes, megabytes, gigabytes, and terabytes are higher units for measuring the capacity of a computer storage device.

8 bits = 1 byte
1024 bytes = 1 kilobyte (KB)
1024 KB = 1 megabyte (MB)
1024 MB = 1 gigabyte (GB)
1024 GB = 1 terabyte (TB)

Data Storage

Computers use two different types of data storage: temporary storage and permanent storage. Temporary storage is handled by Random Access Memory (RAM). Permanent storage is handled by Read-Only Memory (ROM) storage devices.

Temporary storage (RAM)

Random Access Memory (RAM) holds the data and instructions necessary for processing and working with your computer and software programs. RAM also stores the output data temporarily before it is sent to an appropriate output device (such as a printer). You can often increase the speed at which you are able to work with programs by increasing the amount of RAM on your computer.

RAM is volatile. This means that the contents in memory are lost when the computer is turned off. Therefore, a permanent storage area is required to store data and programs.

Permanent storage (ROM)

Read Only Memory (ROM) is a permanent storage area for storing data and programs that are not needed immediately by the computer. ROM is the type of memory that handles this permanent storage of your data on your computer. Software programs are stored in ROM, as are any files you save. The most common permanent storage device is the hard drive on your computer.

The differences between RAM and ROM are given in Table 3.1.

Table 3.1: Differences between RAM and ROM


Random Access Memory (RAM)Read-Only Memory (ROM)
Storage area used for temporarily holding programs and data for processing. Storage area used for holding instructions needed for operating a computer. These instructions are stored permanently. They cannot be erased or modified.
Data stored is lost the moment the power supply is turned off. Information stored is not lost even after the computer is turned off.

Drives for permanent storage

Just as you need an audio player to listen to an audio cassette, you need a storage device called a drive to write to and read from a computer.

Commonly used storage devices include the following:

  • Hard disk drives
  • Floppy disk drives
  • Compact Disc - Read-Only Memory (CD-ROM) drives and CD writers
  • Digital Video Disc (DVD) drives and DVD writers

Hard disk drive

A hard disk drive (see Figure 3.1) is a very typical external storage device found in almost all PCs. The hard disk drive is attached to the system unit from within, but it is possible to remove a hard disk drive from a computer if necessary. The storage capacity of hard disks varies up to a capacity of terabytes, but most home computers currently have hard drives that hold a number of gigabytes.

Figure 3.1: A hard disk in a hard disk drive

Floppy disk drive

The floppy disk drive (see Figure 3.2) is an external storage device used to read from, and write to, a floppy disk.

Figure 3.2: Floppy Disk Drive

A floppy disk (see Figure 3.3) is a portable storage medium that can store a small amount of data. The storage capacity of a floppy disk is usually 1.44 MB. One disadvantage of a floppy disk is that it is prone to damage by heat, dust, and magnetic fields. For example, a simple magnetic paper clip may destroy data stored on a floppy disk. For this reason, you should save important records and other important data either on multiple floppy disks or an alternative medium, such as a compact disc (covered in the next section). A floppy disk is also called a floppy, or a diskette.

Figure 3.3: Floppy disk

Compact Disc - Read Only Memory (CD-ROM) drive

The CD-ROM drive (see Figure 3.4) is an external storage device used to read from a CD-ROM. The storage capacity of most CD-ROMs is approximately 650 MB or 700 MB, which is also the reason why large software programs usually come with an installation CD-ROM. The advantage of a CD-ROM is that the data stored on it is less prone to damage because the data on a CD-ROM cannot be changed.

Figure 3.4: A CD-ROM drive in a system unit

Note  Handle CDs carefully. If the CD is scratched, your computer may not be able to read the CD contents.

Rewritable CDs and CD writers

A CD writer (see Figure 3.5) is a storage device that can write data to a rewritable CD, which is a special type of CD that allows you to erase the content already stored and store data again. CD-writers are capable of storing a large amount of data on a CD. They are also capable of reading CD-ROMs. Keep in mind that CD-ROMs and rewritable CDs are different media types, they only look the same. People tend to call both CDs.

Figure 3.5: CD-Writer

Digital Video Disc (DVD) drive

A DVD drive (see Figure 3.6) is an external storage device used to read from a DVD-ROM, although DVD drives are also able to read CDs. A DVD-ROM is similar to a CD-ROM, except that it can store larger amounts (at least 4.7 GB) of data. Because of their capacity, DVDs are generally used to store very large multimedia presentations and movies that combine high quality sound and graphics.

Figure 3.6: DVD drive

Comparing external storage types

A comparison of a floppy disk, hard disk, CD-ROM, and DVD is given in Table 3.2.

Table 3.2: Comparison of Floppy Disks, Hard Disks, CD-ROMs and DVDs

Floppy diskHard diskCD-ROMDVD
Also referred to as diskette or floppy Also referred to as the fixed disk Also referred to as compact disc Also referred to as digital versatile disc
Removable Usually attached within the system unit Removable Removable
Made of flexible vinyl material Less resistant to damage by heat, dust and magnetic fields. Less prone to damage, since it is inside the system unit and is packed airtight. Reliable because data cannot be altered without a CD writer (rewritable CD only). Reliable because data cannot be altered without a DVD writer (rewritable DVD only).
Storage capacity of 1.44 MB Stores 40 GB of data or more Stores 650 MB to 700 MB of data Store at least 4.7 GB of data
Reads and writes data Reads and writes data Read-only (once written, data cannot be erased or overwritten)Read-only

Activity 3.1.1

List the storage capacity of the devices and rank them in order of storage capacity.

Table 3.3: Storage Capacity of Devices

DeviceStorage capacityRanking in order of storage capacity
a. Floppy disk
b. Hard disk
c. CD-ROM
d. DVD

Session 2: Performance Factors of PCs and Monitors

The performance of a computer depends mainly on how much RAM is on the system and the speed at which instructions and data are processed.

Speed of the Microprocessor

A microprocessor is the component of the system unit that performs the actual processing of data. Microprocessors can manipulate 8, 16, or 32 bits of data at a time. An 8-bit processor can manipulate only a single byte of data at a time. A 16-bit processor can handle 2 bytes while a 32-bit chip can process 4 bytes at a time.

In general, a 16-bit PC will be faster than an 8-bit system and a 32-bit PC will be faster than the 8- and 16-bit models. The transfer of data between the microprocessor, memory, and peripherals is done through the bus. Most current processor designs use a 32-bit bus, meaning that 32 bits of data can be transferred at a time. PCs with a 64-bit bus also exist, but are not as common yet.

Storage Capacity of RAM

The amount of RAM required depends on the programs you run on your computer. Reasonable performance today calls for at least 128 MB of RAM. If you want to run several programs at the same time or work with large files and documents, you need to increase the amount of RAM. Increasing the capacity to 256 MB can measurably increase performance. RAM has become dramatically less expensive in the last decade, so increasing the amount of RAM on your computer is often an economical investment to boost your productivity.

Clock Rate

The fundamental rate at which a computer performs its operations is called the clock rate. The faster the rate, the quicker the microprocessor processes instructions and data. Clock speeds are expressed in megahertz (MHz) or gigahertz (GHz).

Performance Factors of Monitors

Screen resolution is a key characteristic of computer monitors and refers to the number of pixels a screen can display within a given area. For higher legibility of documents on screen, you can generally adjust the screen resolution of your monitor. A higher number of pixels means better clarity in the display.

Another important characteristic is the vertical frequency, which indicates the number of images that can be put together per second. A higher frequency means less stress for the human eye. If you want to look at a computer screen for 45 minutes or more, use a frequency of at least 72 Hz.

Session 3: Computer Maintenance

It is important to maintain computers to ensure sustained performance and longevity of different parts.

General Safety Measures


Do

  • Keep the computer in a cool, dry, and dust-free environment.
  • Shut down the computer and switch off the monitor, system unit, and printer before switching off the main power supply.
  • Cover the system at the end of the day.
  • Have enough space between the computer and the room walls for proper airflow.
  • Connect your computer to an uninterruptible power supply (UPS), if available. A UPS includes a battery that will maintain power supply for a certain time period after a power failure. When there is a power failure, your computer will continue to function for a specified duration. During this time, you can save your unsaved data and turn off your computer properly. Without a UPS, the computer will shut down immediately if there is a power failure and all your unsaved data will be lost.

Do not

  • Do not allow anyone to drink or eat near the computer. Spilling drinks on a keyboard is a common problem and often leads to permanent keyboard damage.
  • Do not expose your computer to direct sunlight to avoid damage due to overheating.
  • Do not place magnets near the computer. Floppies and hard drives are magnetic storage devices and may lose their data.
  • Do not try to open the monitor or system unit, and do not touch the parts inside. You may be endangering your life!

Maintaining the System Unit

It is good practice to maintain the system unit regularly to ensure long life and avoid unnecessary performance problems.


Do

  • Handle the floppy, CD, and DVD drives gently.
  • Shut down the system before you turn off the computer. To do this in Windows XP, click Start, and then click Shut Down.

Do not

  • Do not turn off the computer without shutting down the operating system beforehand.

Maintaining the Monitor

Monitor screens are sensitive to electronic waves from other devices, such as cell phones and audio speakers. Care must be taken to protect your monitor from such disturbances.


Do

  • Turn off the monitor when not in use, to save power.
  • Keep devices that emit electronic signals away from your monitor. They may interfere with the performance of the monitor.

Do not

  • Do not touch the screen with your hands or sharp objects. This may result in fingerprint smudges, dirt, or damage.

Maintaining the Keyboard

The keys on the keyboard are very sensitive. Excessive pressure and dirt on the keys can damage the internal circuitry.


Do

  • Clean your keyboard regularly.
  • Use a small, handheld vacuum cleaner to collect the dust from the keyboard.

Do not

  • Do not strike the keys hard.
  • Do not eat or drink while using your keyboard.

Maintaining the Mouse

The mouse ball inside the mouse enables the mouse to track movements. When the mouse moves over an unclean surface, dirt accumulates over the trackball and the three pinwheels. This affects the precision with which the mouse pointer follows the user's movements. Mouse devices and mouse pads should be free from dust and dirt.


Do

  • Use a mouse pad.
  • If there is no mouse pad, then place the mouse on a clean, flat surface.

Do not

  • Do not stretch the mouse cable.
  • Do not expose the mouse to excessive moisture.

Cleaning a Mouse

To prevent dust from accumulating around the mouse ball, you must clean the mouse regularly.

To clean a mouse

  1. Shut down the computer and unplug the mouse.
  2. Clear the dust on the bottom surface of the mouse.
  3. Open the cover at the bottom of the mouse by turning it counter-clockwise.
  4. Carefully take the mouse ball out.
  5. Use a soft cloth or tissue to wipe the dust accumulated on the ball.
  6. Carefully remove the particles of dust on the three rotating wheels inside the mouse.
  7. Put the mouse ball back in position.
  8. Close the cover by rotating it clockwise to lock it.
  9. Plug the mouse back in and switch on the computer.

Test Your Knowledge

  1. You want to save a report on a removable storage. The data must be kept for several years. Which medium should you choose?
    1. Hard disk
    2. Floppy disk
    3. CD-ROM
  2. Valentina is creating an online presentation on her computer. Whatever she types is stored temporarily
    1. in RAM.
    2. in ROM.
    3. on the hard disk.
  3. Statement A: Bus is used to transfer data between the microprocessor, memory, and peripherals.

    Statement B: The width of the bus determines how many bits of data can be transferred between the microprocessor, memory, and peripherals.

    1. Both statements are true.
    2. Statement A is true and Statement B is false.
    3. Statement A is false and Statement B is true.
  4. Which one of the following disks is usually attached within the system unit?
    1. Floppy disk
    2. Compact disc
    3. Hard disk

Lesson Objective Checklist

Skills AcquiredYesNo
I can identify the function of storage devices.
I can explain the main performance factors of a PC.
I can list guidelines for maintaining a computer.

Terms to Remember

  • A Bit is the smallest unit of measurement of storage capacity.
  • The Bus is a hardware component that carries data within and between the microprocessor, RAM, and peripheral devices.
  • A Byte is a set of eight bits.
  • CD-ROM refers to a compact disc that cannot be overwritten.
  • CD-ROM drive is an external storage device used to read from a CD-ROM.
  • CD writer is a storage device that can write data to a rewritable CD.
  • Clock rate is the fundamental rate at which a computer performs its operations.
  • A Drive is a storage device used to write to and read from a storage medium.
  • A DVD drive is an external storage device used to read from a DVD-ROM.
  • External Storage refers to a permanent storage area required to store data and programs that are not needed immediately by the computer.
  • Floppy disks are portable storage media that can store a small amount of data.
  • A Floppy disk drive is an external storage device used to read from and write to a floppy disk.
  • The Hard disk drive is an external storage device attached to the system unit from within. A hard disk drive can be found in almost any PC.
  • A Microprocessor is the component of the system unit that performs the actual processing of data.
  • Primary storage refers to the internal storage, or main memory of a computer. It contains data and instructions for processing. It also holds the output data temporarily before it is sent to an appropriate output device.
  • RAM, Random Access Memory, refers to a storage area used for temporarily holding programs and data for processing.
  • ROM, Read Only Memory, refers to a storage area used for holding instructions needed for starting a computer. These instructions cannot be erased or modified.
  • Screen resolution refers to the number of pixels a screen can display within a given area.