CLASS
IX
CHAPTER-1 (Basics of Computer Technology)
Question: What is Computer? Writes its characteristics.
Answer: COMPUTER: Computer is an electronic machine which processes
raw data to give meaningful information. It accepts information (in the form of digitized data) and manipulates it for some result based on a program.
Characteristics of Computer are:-
1. SPEED: Computer is very
fast calculating device. It can execute basic operations like subtraction, addition,
multiplication and division at a few microseconds. It can move and copy data at
a speed in the order of billion instruction per second.
2. ACCURACY: Computer always
gives accurate results. The accuracy of Computer does not go down when they are
used continuously for hours together.
It always gives
accurate results.
3. STORAGE CAPACITY :
Computer has a very large storage capacity. A large volume of information
can be stored in the memory of computer and information can be retrieved
correctly when desired.
4. VERSATILITY: The working of
computer with different types of data is known as versatility. That means
computer can perform different types of job efficiently. Computer can works
with different type of data and information such as visuals, text, graphics
& video etc. So, versatility is a most important characteristic of
computer.
5. DILIGENCE: A Computer can
work for long hours with the same accuracy and speed because it is free from
problems of boredom or lack of concentration.
6. NO THOUGHTS: Computers have
no thoughts because they are machine and they are devoid of emotions. They have
no feelings. Since, computers have no thoughts and feelings so they can't make
judgment based on thoughts and feelings.
Question: Write down the components of
computer system?
Answer: A computer system consists of mainly four basic units; namely input
unit, storage unit, central processing unit and output unit. Central Processing
unit further includes Arithmetic logic unit and control unit.
Input Unit: This unit is used for entering
data and programs into the computer system by the user for processing.
Storage Unit: The storage unit is used
for storing data and instructions before and after processing.
Output Unit: The output unit is used for
storing the result as output produced by the computer after processing.
Processing: The task of performing
operations like arithmetic and logical operations is called processing. The
Central Processing Unit (CPU) takes data and instructions from the storage unit
and makes all sorts of calculations based on the instructions given and the
type of data provided. It is then sent back to the storage unit. CPU includes
Arithmetic logic unit (ALU) and control unit (CU)
Question: What is memory?
Answer: Computer memory is any physical device capable
of storing information temporarily or permanently. For example, Random Access
Memory (RAM), is a
volatile memory that stores information on an integrated
circuit used by the operating system, software, and hardware.
Question: What is memory and write its types.
Answer: A
memory is just like a human brain. It is used to store data and instructions.
Computer memory is the storage space in computer where data is to be processed
and instructions required for processing are stored. The memory is divided into
large number of small parts called cells. Each location or cell has a unique
address which varies from zero to memory size minus one. For example if
computer has 64k words, then this memory unit has 64 * 1024=65536 memory
locations. The address of these locations varies from 0 to 65535.
Memory is primarily of three types:-Cache Memory: Cache memory is a very high speed semiconductor memory which can speed up CPU. It acts as a buffer between the CPU and main memory. It is used to hold those parts of data and program which are most frequently used by CPU. The parts of data and programs are transferred from disk to cache memory by operating system, from where CPU can access them.
Advantages
The advantages of cache memory are as follows:
·
Cache memory is faster than
main memory.
·
It consumes less access time as
compared to main memory.
·
It stores the program that can
be executed within a short period of time.
·
It stores data for temporary use.
Disadvantages
The disadvantages of cache memory are as follows:- Cache memory has limited capacity.
- It is very expensive.
Primary Memory (Main Memory): Primary memory holds only those data and instructions on which computer is currently working. It has limited capacity and data is lost when power is switched off. It is generally made up of semiconductor device. These memories are not as fast as registers. The data and instruction required to be processed reside in main memory. It is divided into two subcategories RAM and ROM.
Characteristics of Main Memory
- These are semiconductor memories
- It is known as main memory.
- Usually volatile memory.
- Data is lost in case power is switched off.
- It is working memory of the computer.
- Faster than secondary memories.
- A computer cannot run without primary memory.
Secondary Memory: This type of memory is also known as external memory or non-volatile. It is slower than main memory. These are used for storing data/Information permanently. CPU directly does not access these memories instead they are accessed via input-output routines. Contents of secondary memories are first transferred to main memory, and then CPU can access it. For example: disk, CD-ROM, DVD etc.
Characteristic of Secondary Memory
- These are magnetic and optical memories
- It is known as backup memory.
- It is non-volatile memory.
- Data is permanently stored even if power is switched off.
- It is used for storage of data in a computer.
- Computer may run without secondary memory.
- Slower than primary memories.
Question: What are the storage devices?
Answer: There are two types of storage devices used
with computers: a primary
storage
device, such as RAM, and a secondary
storage
device, like a hard
drive.
Secondary storage can be removable, internal, or external storage
Question: What is I/O device?
Answer:
INPUT DEVICES: Any machine that feeds data into a computer. For example, a keyboard
is an input device, whereas a display monitor is an output device. Input
devices other than the keyboard are sometimes called alternate input
devices. Mice, trackballs, and light pen all alternate input devices.
a)
Graphics Tablets
b)
Cameras
c)
Video Capture Hardware
d)
Trackballs
e)
Barcode reader
f)
Digital camera
g)
Gamepad
h)
Joystick
i)
Keyboard
j)
Microphone
k)
MIDI keyboard
l)
Mouse (pointing device)
m) Scanner
n)
Webcam
o)
Touchpads
p) Pen
Input
q)
Microphone
r)
Electronic Whiteboard
OUTPUT DEVICES: An
output device is any piece of computer
hardware equipment used to communicate the results of data processing carried
out by an information processing system (such as a computer) which converts the electronically generated information
into human-readable form.
- Monitor
- Printers (all types)
- Plotters
- Projector
- LCD Projection Panels
- Computer Output Microfilm (COM)
- Speaker(s)
Both Input–Output
Devices:
- Modems
- Network cards
- Touch Screen
- Headsets (Headset consists of Speakers and Microphone).
