computer fundamental

1. Components of Computer
The components can be classified into two broad categories as :
Hardware
Software
Hardware
Hardware refers to any physical component of a computer. For
example, CPU, Monitor, Keyboard, Hard Disk, Floppy Disk,
Printer, etc. Are physical components and thus, is hardware.
Software
Software refers to the programs, which are required to operate
the computer. In other words, we can describe software as the
logical entity, which enables the physical entities (hardware) to
function properly.
“ A set of programs is also called as Software.”

2. Organization of Computer
A computer system has
the following main
components -
· Input Unit/Devices
· Output Unit/Devices
· Central Processing
Unit
· Memory Unit/Storage
Devices

3. Central Processing Unit
Central Processing Unit (CPU) is the main component or “brain”
of a computer, which performs all the processing of input
data. Its function is to fetch, examine and then execute the
instructions stored in the main memory of a computer. In
microcomputers, the CPU is built on a single chip or
integrated Circuit (IC) and is called as a Microprocessor. The
CPU consists of the following distinct parts:
· Arithmetic Logic Unit (ALU)
· Control Unit (CU)
· Registers
· Buses
· Clock

4. Arithmetic Logic Unit
The arithmetic and logic unit of CPU is
responsible for all arithmetic operations like
addition, subtraction, multiplication and
division as well as logical operations such as
less than, equal to and greater than. Actually,
all calculations and comparisons are
performed in the arithmetic logic unit.

5. Control Unit
The control unit is responsible for controlling the
transfer of data and instructions among other
units of a Computer. It is considered as the
“Central Nervous System” of computer, as it
manages and coordinates all the units of the
computer. It obtains the instructions from the
memory, interprets them and directs the
operation of the computer. It also performs the
physical data transfer between memory and
the peripheral device.

6. Registers
Registers are small high-speed circuits (memory locations),
which are used to store data, instructions and memory
addresses (memory location numbers), when ALU
performs arithmetic and logical operations. Registers can
store one word of data (1 word = 2 bytes & 1 byte = 8
bits. Depending on the processor’s capability, the
number and type of registers vary from one CPU to
another. Registers can be divided into six categories viz.
General Purpose Registers, Pointer Registers, Segment
Registers, Index Registers, Flags Register and
Instruction Pointer Register, depending upon their
functions.

7. Buses
Data is stored as a unit of eight bits (BIT stands for Binary
Digit i.e. 0 or 1) in a register. Each bit is transferred from one
register to another by means of a separate wire. This group of
eight wires, which is used as a common way to transfer data
between registers, is known as a bus. It is actually a connection
between two components to transmit signal between them.
Bus can be of three major types viz. Data Bus, Control Bus
and Address Bus. The data bus is used to move data, address
bus to move address or memory location and control bus to
send control signals between various components of a
computer.

8. Clock
Clock is another important component of CPU, which measures and allocates a fixed
time slot for processing each and every micro-operation (smallest functional
operation). COMPUTER AWARENESS FOR Central Processing Unit (CPU) is
the main component or “brain” of a computer, which performs all the processing
of input data. Its function is to fetch, examine and then execute the instructions
stored in the main memory of a computer. In microcomputers, the CPU is built on
a single chip or integrated Circuit (IC) and is called as a Microprocessor. The
CPU consists of the following distinct parts:
· Arithmetic Logic Unit (ALU)
· Control Unit (CU)
· Registers
simple terms, CPU is allocated one or more clock cycles to complete a micro-
operation. CPU executes the instructions in synchronization with the clock pulse.
The clock speed of CPU is measured in terms of Mega Hertz (MHz) or Millions of
Cycles per second. The clock speed of CPU varies from one model to another in
the range 4.77 MHz (in 8088 processor) to 266 MHz (in Pentium II). CPU speed
is also specified in terms of Millions of instructions Per Second (MIPS) or Million
of Floating Point Operations Per Second (MFLOPS). Now these days we have
clock speeds of CPU which in Gigahertz. E.g. we have Pentium IV having a clock
speed of 3.04GHz, or AMD Athlon having speed of 2.7GHz.

9. Storage Unit / Memory Unit
Memory Unit is that component of a computer system, which
is used to store the data, instructions and information before,
during and after the processing by ALU. It is actually a work
area (physically a collection of integrated circuits) within the
computer, where the CPU stores the data and instructions. It is
also known as a Main/Primary/internal Memory.
Storage unit also consist of storage devices, which stores the
data on permanent basis. I.e. unless or until we want to delete
the data by ourselves the data will be available even if the power
goes off. Hard disks, Compact Disks, Floppy disks are the
examples of secondary storage devices.

10. Storage Unit / Memory Unit
Memory Unit is that component of a computer system, which
is used to store the data, instructions and information before,
during and after the processing by ALU. It is actually a work
area (physically a collection of integrated circuits) within the
computer, where the CPU stores the data and instructions. It is
also known as a Main/Primary/internal Memory.
Storage unit also consist of storage devices, which stores the
data on permanent basis. I.e. unless or until we want to delete
the data by ourselves the data will be available even if the power
goes off. Hard disks, Compact Disks, Floppy disks are the
examples of secondary storage devices.