IT refers to technologies that allow users to record, store, process, transmit, and receive information. A computer takes data as input, transforms it according to stored instructions, and outputs the processed information. The central processing unit (CPU) controls and manipulates data in a computer's memory, arithmetic logic unit (ALU), and control unit. The control unit obtains and interprets instructions to notify other components, while the ALU performs logical and arithmetic operations. Memory stores programs and data during processing in volatile, randomly accessible locations. Input and output units convert and display data. Secondary storage provides long-term, non-volatile data storage outside the CPU.

1. INFORMATION TECHNOLOGY
IT is the term used to describe technologies
which enable the users to record, store, process,
retrieve, transmit and receive information.

2. WHAT IS A COMPUTER ?
A physical device that takes data as input,
transforms these data according to stored
instructions and output the processed information

3. BASIC ANATOMY OF COMPUTER
ALU CONTROL
UNIT
INPUT OUTPUT
MAIN
UNIT MEMORY UNIT
SECONDARY
MEMORY

4. • Central Processing Unit (CPU) – It manipulates
raw data into a more useful form and controls other
parts of the computer system. It is referred as the
“brain” of the computer system. CPU has three main
parts:
– Memory Unit
– Control Unit
– Arithmetic Logic Unit (ALU)

5. • Control Unit – Obtains instructions from the
computer systems’ memory, interprets them and
notifies the other components in the system to carry
them out.
• Control unit has special storage locations called
registers.
• Main registers of control unit:
– Instruction register- holds instruction currently being
executed.
– Instruction address register- holds the address of the next
instruction to be executed.
– General purpose register-hold data for temporary storage.
– Storage address register and storage data register- hold
the address & content respectively of a storage instruction
prior to data being placed into a location transferred from it.

6. • Arithmetic and Logic Unit (ALU) – It processes data
obtained from memory under the direction of the
control unit. It performs the computers’ principal
logical and arithmetic operations.
• Main registers of ALU:
– Accumulator- used when the unit is performing arithmetic
operations.
– Program counter- keeps track of the items of information
stored in the memory cell.

7. • Memory Unit – The place where computer programs
and data are stored during processing.
• Divided in to storage locations called bytes.
• It has the following characteristics:
– Volatile
– Randomly accessed
– Fast
– Expensive
• Main memory has three functions:-
– it stores all or part of the software program that is
being executed.
– it also stores the operating system program that
manage the operation of the computer.
– it holds data that the program is using.

8. • Random access Memory – it consists of
storage locations in which data can be stored
and retrieved directly.
• Read Only Memory (ROM) : which can only be read,
is non-volatile,can not be written to or altered, can be
changed by removing old ROM chips & inserting new
ROM chips containing new programs.
• Types of ROM:
PROM (Programmable Read Only Memory)-allows
to read a program into it.
EPROM (Erasable Programmable Read Only
Memory)-allows programs in ROM to be altered with
special equipment.

9. • Input unit – gather data & convert them in to
electronic form. Example:---Keyboard, Terminals,
Touch Screen, Joy Stick, Light Pen, Digitiser.
• Output unit- display data after they have been
processed. Example:---Display Screen, Printers,
Plotters.
• Secondary storage-used for long term storage of
data outside the CPU. It is non-volatile. Magnetic
disks,optical disk,magnetic tape are few secondary
storage devices.