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					INPUT, OUTPUT and MEMORY
DEVICES

      Notes
      Assignment
           1.   Assignment one
                Solved problems
           2.   Assignment two
                Unsolved prob.
                Short Answer type
           3. Assignment three
                Unsolved prob.
                Long answer type



                NOTES


1) INPUT DEVICES - The devices which are responsible for taking input from
   input unit are called Input Devices. Some most common input devices are:-


     a) Keyboard - Keyboard is a typewriter like device which is used to type in
           the letter, digits and commands. A keyboard contains a matrix of
           switches.


     b) Mouse – A mouse is a pointing device with a roller on its base n
           controls the pointer on screen. When a mouse moves on flat surface, the
           cursor on the screen also moves in the direction of mouse movement’s.


     c) Microphone (Mic) – Sending sound input to computer through a special
           device called Microphone.


2) OUTPUT DEVICES – The Devices which are responsible for producing output
   from output unit in user readable form. Some of the common output devices
   are:-
     a) Monitor – It is the most common form of output from a computer. It
        display information in a similar way to that shown on a television. The
        two most common types of monitor are:-


     i) Cathode Ray Tube (CRT) - It is the most vital component in most
         computer n television. It is responsible for the images that we see in
         television or in computer.
     ii) Liquid crystal display – it is a type of display used in watches n
         computer. It uses liquid crystals which are used to create pixel on the
         screen.

          TFT- TFT (Thin Film Transistor) is a device within each
          pixel that sets the charge.




     b) Printers – it is a device through which a computer can print character
        or text on a page.
        There are two types of printers-

          i.   Impact printer – the printers in which there is a mechanical
               contact btw the print head and paper.
               Mast common impact printer is
               Dot-matrix printer- it prints one character at a time.
         ii.   Non-impact printers – it is a type of printer that doesn’t operate by
               striking a head against ribbon.
               It is categories into 5 parts;
                  I.  Electromagnetic printers
                 II.  Thermal printers
                III.  Electrostatic printers
                IV.   Inkjet printers
                 V.   Laser printers
     c) Speakers – the devices which are used to receive the sound in form
        of electric current from the sound card and then convert it to sound
        format.

3) MEMORY DEVICES – memory is used to store both the instructions to be
   executed and data.


       The no. of bits, a memory word consists of is known as
       Word length.
It is two types:-
          a) Volatile memory
          b) Involatile memory



    i)   THE MAIN MEMORY – it is primary memory. Broadly it is divided into
         two parts:-
    I)    RAM (RANDOM ACCESS MEMORY) – It is a form of computer DATA
          STORAGE. In RAM the memory cells can be accessed for
          information transfer from any desired random locations.
          It is volatile memory i.e., when the power goes off, the contents of
          RAM get erased.
          BLOCK DAIGRAM

                                                K data input lines
                  N address lines
                                     Memory unit
                  Read
                                     2ⁿ words
                    Write
                                     K bits per word

                                                N data output lines




          Types of RAM
          !) Dynamic RAM (DRAM) – it is a type of random-access memory

           That stores each bit of data in a separate capacitor within an
           integrated circuit. The capacitor can be either charged or
           discharged; these two states are taken to represent the two values
           of a bit, conventionally called 0 and 1.
            A.) Types of DRAM are:-
           i- EDO DRAM
          Ii- Synchronous DRAM
         Iii- Rambus DRAM
         Iv- Double Data Rate
             @) STATIC RAM – it is also volatile but as long as they are supplied
with power, they need no special regenerator circuits to retain the stored data.
The static RAM consists eventually of internal flip-flops that store the binary
information.




         IB) READ ONLY MEMORY (ROM) - A memory unit that performs the read
         operation only; it does not have a write capability. This implies that the
         binary information stored in a ROM is made permanent during the h/w
         production of the unit and cannot be altered by writing different words
         into it (non-volatile).
         Types of ROM:-
                 (i) Programmable Read Only Memory (PROM) – it is a ROM that
                      can be programmed to record information using a facility
                      known as PROM-programmer.
                 (ii) Erasable Programmable Read Only Memory (EPROM) – it is
                      another type of ROM that can be erased and the chip can be
                      reprogrammed to record different information using a special
                      PROM-program facility.
                 (iii)      Electrically Erasable PROM (EEPROM) - this type of ROM
                      can be programmed and erased by electrical signals.

      II)   Cache Memory – It is a high speed memory available inside CPU in
            order to speed up access to data and instruction stored in RAM
            memory.
            There are two types of memory:-
                 (i)   Level (L1) cache – it is built inside the CPU package.
                 (ii)  Level (L2) cache – it is built outside the CPU and resides
                       on the motherboard.
     III)   The Secondary Memory Devices – as all we know that primary
            memory is limited and is not permanent, secondary storage devices
            are used to store large amount of data permanently.
            Some most common storage devices are:
          (a) Hard disks – It is a non-volatile, random access digital
              data storage device which record data by magnetizing
              ferromagnetic material directionally.


Concentric circles on the magnetized surface of the magnetic disks are known as
tracks.

The tracks on the disk surface are divided into invisible segments know as sector




          (b) Floppy Disks – The floppy disks are one of the oldest
             types of portable storage device still in use. The floppy
             disks enable one to transfer small files btw computers
             and also store data/information as backup.

          (c) Compact Disks (CDs) – These are also storage devices.
              There are three types of CDs :-


                      I)    CD-ROM (Compact Disk- Read only memory
                            -- This are used to store information and
                            cannot be used to store data. these are
                            used to record information including text,
                            graphics or audio on the CD distribution.
                    II)     CD-R (Compact Disk-Recordable) – data can
                            be recorded on these disks only one. Each
                            part of a CD-R can be written on only once
                            and disk can’t be erased.
                    III)    CD-RW (Compact Disk rewritable) – CD-RW
                            is an erasable disk as you can write on
                            multiple times.
          (d) DVDs (Digital Video Disks) – It is same as CDs but it is
              able to hold about 15 times much more data then the
              CDs. It is also divided into three types :-
                       I)      DVD-ROM (Read Only Memory) – it is high
                               capacity disk which is capable of storing
                               4.7 GH to 17 GB.
                       II)     DVD-R (Recordable)—it is similar to CD-R
                               as it allow user to write on the disc one’s
                               but it may read it many times.
                                      III)    DVD-RW(Rewritable) --- it is data storing
                                              disk which allow user to write on disk as
                                              many times as user wants


                 Hard disk and Floppy disks are Magnetic Media whereas CDs and DVDs
                 are optical Media.



4) Ports – These are used to connect external devices to the computer.
   There are 7 types of ports:-

   I)     Serial Ports— it transfers data serially a bit at a time. The disadvantage
          of serial port is that it takes 8 times longer to transmit a byte. They are
          typically used to connect devices like mouse and modem.
   II)    Parallel Ports --- it can send or receive one byte at a time. These are
          popularly used to connect printer, scanner, CD writer, etc.
   III)   USB (Universal Serial Bus) Ports—it gives you a single, standardized,
          easy to use way to connect a variety of devices to a computer such as
          printer, joy stick, web cam, etc.
   IV)    AGP Ports – The AGP (Accelerate graphics port) is used to connect to
          graphic card that provides high speed video performance typically
          required in games and other multimedia applications.
   V)     Infrared Port – It is a port which sends and receives infrared signals
          from other devices. In this special form of radio transmission is
          modulated with information and sent from a transmitter to a receiver
          over a relatively short distance. It plays an important role in wireless
          communication due to the popularity of laptop computer, personal
          digital assistants (PDAs), mobiles etc.

                   An infrared communication also contains transceiver that is a
                            combination of a transmitter and receiver.


   VI)    Bluetooth – Bluetooth is a telecommunications industry specification
          that describes how mobile phones, computer, can be easily
          interconnected using a short range wireless connections. Using this
          technology, users of cellular phones, pagers can buy a three-in-one
          phone that can double as a portable phone at home or in office, in
          general have all mobile and fixed computer devices be totally
          coordinated.
   VII)   PS-2 Port – it is an electronic receptacle or plug found on computers. It
          accepts a PS/2 cable with a mini-DIN connector from becoming bent.
                               ASSIGENMENT ------ 1



                                SOLVED PROBLEMS

1) What is the function of the memory? What are its measuring units?
Sol. The memory temporarily holds the data and information during processing.
The smallest unit of memory is a byte. A byte can store one character binary
form.
Byte = 8 bits
Kilobytes = 1024 bytes
Megabytes = 1024 KB
Gigabyte = 1024 MB.

2) Suggest suitable devices or media for the following:
              (a) High quality print.
              (b) Quiet printing
              (c) Economical printing of small quantity of data.
Sol. (a) Non-impact printer
     (b) Laser printers
     (c) Impact printers

3) Define PROM.
   Sol. Programmable Read Only Memory (PROM) is a ROM that can be program
   to record information using a facility known as PROM-programmer. Once the
   chip has been programmed, the recording information cannot be change.

4) What is the difference between RAM & ROM?
   Sol. RAM refers to random access memory where both read and write
   operations can be take place. But the RAM is a volatile memory; its contents
   are lost when power is turned off.
   ROM refers to reads only memory where only read operations take place. The
   ROM is a non volatile memory.

5) What is TFT?
   Sol. TFT (Thin Film Transistor) is the devices within each pixel that sets the
   charge. And sometimes they are called “Liquid Crystal Display” referring to
   the material they use or they are referring to the tiny transistor that makes
   them work.




                                ASSIGNMENT-2
                      UNSOLVED PROBLEMS (Short Ans. Type)

   1) Give some examples of input and output unit.
   2) What are pixels?
   3) What is word length?
   4) Differentiate btw volatile and non volatile memory?
   5) Define Tracks?
   6) Define Sectors?
   7) give the full form of the following;
    (I) VDU
    (II) TFT
    (III) CD-R
    (IV) LCD
   8) Give some example of Non- impact printer?
   9) Give one difference btw RAM & ROM?
   10) What is a byte?



                               ASSIGNMENT-3
                      UNSOLVED PROBLEMS (Long Ans. Type)
1) State the basic units of the computer, Name the subunits that make up the
CPU and give the function of each of the units?
2) Why is primary memory termed as ‘destructive memory’ but ‘non
destructive read memory’?
3) Why is input unit needed in a computer? Discuss various types of input
devices along with their working mechanism.
4) Why is output unit needed in a computer? Discuss various types of output
devices along with their working mechanism.
5) What are the two categories of printers? Which one is more speedy and
Why?
6) What are secondary storage devices? Give some examples and also define
them?
7) What is CRT?
8) Define cache memory n its types?
9) What are ports? How many types of ports are there?
10) What is RAM & ROM? Give three difference btw them?

				
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