IT Literacy 1

  • Basic knowledge on key input/output devices attached to the computer system

  • Knowledge about basic usage of a computer

  • Knowledge about basic storage methods of information

What is computer ?

Computer is a data processing machine which needs user’s instructions to perform any job. After processing the raw facts (called data), it produces useful information for the user.

But how do you give data and instructions to the computer and how it can return the useful information to you. To do all these, different types of input and output devices can be connected with the computer.

Input Devices

The devices which are used to give data and instructions to the computer are called Input Devices. Various types of input devices can be used with the computer depending upon the type of data you want to enter in the computer,


  • Keyboard

  • Computer mouse

  • Graphic tablet

  • Touchscreen

  • Barcode reader

  • Image scanner

  • Microphone

  • Webcam

  • Game controller

  • Light pen

  • Scanner

  • Digital camera


It is the most commonly used input device. It is used to enter data and instructions directly into the computer. There are 104 buttons on the keyboard which are called keys.

The various types of computer keyboards typically used by computer users for different purposes are a qwerty keyboard, a gaming keyboard, a virtual keyboard and a multimedia keyboard. Based on the connectivity options used for a keyboard to connect with a computer, it is classified as a wired keyboard, a wireless keyboard, a Bluetooth keyboard and an USB keyboard.


Mouse is another input device which is commonly found connected with the computers. It is basically a pointing device which works on the principle of Point and Click. When the mouse is moved on the mouse pad, a light beam underneath reflect to give motion to the pointer on the screen.

The mouse is used in windows based programs, where the user can run the commands by pointing the objects with the help of pointer and clicking the buttons on the mouse. We also use mouse for drawing in paint and kid pix.

Most of the latest mouses, these days, include a wheel in the middle of two buttons that help us to scroll through documents more easily. we use our forefinger to move the wheel to scroll up or down in a document. Optical mouse uses red light to track the movement of mouse for moving the pointer on the computer screen. This type of mouse is more accurate and reliable than the traditional mouse.

Nowadays cordless mouse is very popular. it dose not have wires. it either uses Bluetooth technology to sends the data through the air to a receiver, usually plugged in USB port of the computer.


A scanner or optical scanner is a hardware input device that optically "reads" and image and converts it into a digital signal. For example, a scanner may be used to convert a printed picture, drawing, or document (hard copy) into a digital file which can be edited on a computer.

A scanner can connect to a computer using many different interfaces although today is most commonly connected to a computer using a USB cable.

Output Devices

The devices which are used to display the results or information are called Output Devices. You can view the output on the monitor or you can print it on a paper using a printer. Monitor and the printer are the commonly used output devices.


  • Computer display

  • Printer

  • Projector

  • Speaker


This is the most common output device connected with the computer to display the processed information. It looks like a TV and is also know as VDU(Visual Display Unit). Pictures are displayed by using a large number of very small dots on screen called pixels. The number of pixels that a monitor can show on its screen is referred to as the resolution of the screen

The two commonly used monitor types are:

  1. Cathode Ray Tube (CRT)Monitor

  2. Liquid crystal Display (LCD)Monitor

Add to Your knowledge LCD uses very small amount of electricity as compound to CRT.

The output produced on the screen is called Soft Copy Output because it cannot be retained for a long time.

Nowadays LCD monitors are more popular as their sharp picture quality. They are light weighted and flat screen monitors.


This is an important output device of the computer system. It gives a printed output of the results that appears on the monitor screen. Printed output is also called Hard Copy output because unlike monitor, this output can be preserved even if the computer is switched off.

Printers are of different types. On the basis of their printing techniques, printers are grouped as follows:

  1. Character printer

  2. Line printer

  3. Page printer

Computer Memory

In computing, memory refers to the devices used to store information for use in a computer. The term primary memory is used for storage systems which function at high-speed (i.e. RAM), as a distinction from secondary memory, which provides program and data storage that is slow to access but offer higher memory capacity. If needed, primary memory can be stored in secondary memory, through a memory management technique called “virtual memory.” An archaic synonym for memory is store.

Volatile Memory - RAM

RAM stands for Random-Access Memory

Volatile memory is computer memory that requires power to maintain the stored information. Most modern semiconductor volatile memory is either Static RAM (see SRAM) or dynamic RAM (see DRAM). SRAM retains its contents as long as the power is connected and is easy to interface to but uses six transistors per bit. Dynamic RAM is more complicated to interface to and control and needs regular refresh cycles to prevent its contents being lost. However, DRAM uses only one transistor and a capacitor per bit, allowing it to reach much higher densities and, with more bits on a memory chip, be much cheaper per bit. SRAM is not worthwhile for desktop system memory, where DRAM dominates, but is used for their cache memories. SRAM is commonplace in small embedded systems, which might only need tens of kilobytes or less. Forthcoming volatile memory technologies that hope to replace or compete with SRAM and DRAM include Z-RAM, TTRAM, A-RAM and ETA RAM.

Non-Volatile Memory - ROM

Non-volatile memory is computer memory that can retain the stored information even when not powered. Examples of non-volatile memory include read-only memory (see ROM), flash memory, most types of magnetic computer storage devices (e.g. hard disks, floppy discs and magnetic tape), optical discs, and early computer storage methods such as paper tape and punched cards. Forthcoming non-volatile memory technologies include FeRAM, CBRAM,PRAM, SONOS, RRAM, Racetrack memory, NRAM and Millipede.

Types of Hard Drives

  1. Parallel ATA (PATA)

  2. Serial ATA (SATA)

  3. Small Computer System Interface (SCSI)

  4. Solid State Drives (SSD)

10 Digital Data Storage Devices for Computers

  1. Hard Drive Disks

  2. Floppy Disks

  3. Tapes

  4. Compact Discs (CDs)

  5. DVD and Blu-ray Discs

  6. USB Flash Drives

  7. Secure Digital Cards (SD Card)s

  8. Solid-State Drives (SSDs)

  9. Cloud Storage

  10. Punch Cards

6 Common Causes of Digital Data Loss

There are a number of ways that digital data can be lost. Here are six of the most common ways below. Generally speaking, the best way to protect data is to back it up in different places.

  1. Accidental deletions: This is a very common problem and has happened to most people who deal with data. As well as deletion, reformatting a device can also result in the loss of stored information.

  2. Power failures: Many electronic devices depend on electricity to function properly and maintain data. A loss of power can therefore be disruptive or destructive, especially in cases where the power loss is sudden. As well as power losses, power surges can also cause problems.

  3. Spills, drops, and other physical accidents: Anything that causes physical damage to the storage device can corrupt data or prevent access to it. Even minor accidents, such as knocking over a cup of coffee, might be all it takes to cause the loss of large amounts of data.

  4. Viruses and other forms of malware: Many modern forms of digital data storage are exposed to the internet. This means that the data risks being corrupted by malware, either directly, or via wider damage being caused to say, the operating system.

  5. Theft: Whether through burglary, pickpocketing, mugging, or other forms of theft, you can lose the entire device and all the information that's on it.

  6. Fires, floods, explosions, and other catastrophic events: These can all destroy vast amounts of data. This is one of the main reasons why data should never be backed up in the same building, but rather in a separate place.

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