INPUT, OUTPUT and MEMORY
1. Assignment one
2. Assignment two
Short Answer type
3. Assignment three
Long answer type
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
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
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
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
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
It is two types:-
a) Volatile memory
b) Involatile memory
i) THE MAIN MEMORY – it is primary memory. Broadly it is divided into
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.
K data input lines
N address lines
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
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
(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
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
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
(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
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
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
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
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;
8) Give some example of Non- impact printer?
9) Give one difference btw RAM & ROM?
10) What is a byte?
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
6) What are secondary storage devices? Give some examples and also define
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?