Basics of Information Tecn

1. Computer Systems
Basics of Information
Technology

2. WHAT IS A COMPUTER?
 Computer is an electronic device which is used to
store the data, as per given instructions it gives
results quickly and accurately.
 Data : Data is a raw material of information.
 Information : Proper collection of the data is called information.

3. Characteristics of a computer
 SPEED : In general, no human being can compete to solving the complex computation, faster
than computer.
 ACCURACY : Since Computer is programmed, so what ever input we give it gives result
with accuratly.
 STORAGE : Computer can store mass storage of data with appropriate formate.
 DILIGENCE : Computer can work for hours without any break and creating error.
 VERSATILITY :We can use computer to perform completely different type of work at the
same time.
 POWER OF REMEMBERING : It can remember data for us.
 NO IQ : Computer does not work without instruction.
 NO FEELING : Computer does not have emotions, knowledge, experience, feeling.

4. Computer and its components
 Computer : Computer itself a combination of different type of separate
electronic device. i.e. Computer only will be computer if it has INPUT
DEVICE, PROCESS UNIT, and OUTPUT DEVICE

5. Input device
 Input device enables the user to send data, information, or control signals
to a computer.

6. Output Device
 An output device is any piece of computer hardware equipment which
converts information into human-readable form.

7. CPU-Central Processing Unit
 The CPU is the primary component of a computer that processes
instructions. It runs the operating system and applications, constantly
receiving input from the user or active software programs. It processes the
data and produces output, which may stored by an application or displayed
on the screen.
 It is known as the brain of computer.

10.  An arithmetic-logic unit (ALU) is the part of a computer processor (CPU) that carries
out arithmetic and logic operations on the computer. In some processors, the ALU is
divided into two units, an arithmetic unit (AU) and a logic unit (LU).
 The control unit (CU) is a component of a computer's central processing unit (CPU)
that directs operation of the processor. It tells the computer's memory, arithmetic/logic
unit and input and output devices how to respond to a program's instructions.
 Registers are a type of computer memory used to quickly accept, store, and transfer
data and instructions that are being used immediately by the CPU.The registers used by
the CPU are often termed as Processor registers.

11. Computer - Memory
 A memory is just like a human brain.
 It is used to store data and instructions.
 Computer memory is the storage space in the 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.
 Memory is primarily of three types −
 Cache Memory
 Primary Memory/Main Memory
 Secondary Memory

12.  Cache Memory- Cache memory is a very high speed memory which can
speed up the CPU. It acts as a buffer between the CPU and the main
memory. It is used to hold those parts of data and program which are most
frequently used by the CPU.
 Primary Memory (Main Memory) - Primary memory holds only
those data and instructions on which the computer is currently working. It
has a limited capacity and data is lost when power is switched off. It is
divided into two.RAM and ROM.
 Secondary Memory - This type of memory is also known as external
memory or non-volatile. It is slower than the 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.The
contents of secondary memories are first transferred to the main memory,
and then the CPU can access it. For example, disk, CD-ROM, DVD, etc.

13. RAM (Random Access Memory)
 RAM (Random Access Memory) is the internal memory of the CPU for
storing data, program, and program result.
 It is a read/write memory which stores data until the machine is working.
 As soon as the machine is switched off, data is erased.
 Also known as volatile memory. i.e. data stored in it is lost when we switch
off the computer or if there is a power failure.

14. ROM (Read Only Memory)
 It is the memory for which we can only read but cannot write on it.
 This type of memory is non-volatile.
 The information is stored permanently in such memories during manufacture.
 A ROM stores such instructions that are required to start a computer.
 This operation is referred to as bootstrap.

15.  Memory unit is the amount of data that can be stored in the storage unit.
This storage capacity is expressed in terms of Bytes.
 The main memory storage units
 1Bit (Binary Digit)- A binary digit is logical 0 and 1 representing a
passive or an active state of a component in an electric circuit.
 Nibble-A group of 4 bits is called nibble.
 Byte- A group of 8 bits is called byte.A byte is the smallest unit, which can
represent a data item or a character.

16.  Kilobyte (KB) 1 KB = 1024 Bytes
 Megabyte (MB) 1 MB = 1024 KB
 GigaByte (GB) 1 GB = 1024 MB
 TeraByte (TB) 1TB = 1024 GB
 PetaByte (PB) 1 PB = 1024TB