Computer Organization
Computer System Architecture
8/1/2023
Notes of CO BCA part 2
Vijay pal
, Unit – 1
Components of Computer
CPU
MAR
RAM
MBR
ROM
Input devices Output devices
Secondary memory
Central Unit
Arithmetic logical unit
Keyboard, Printer,
Mouse, Monitor,
Scanner etc. Speaker etc.
MAR – Memory Address Register
MBR – Memory Buffer Register
A system maintain different units for executing a program or
instructions from input to processing unit and processing unit to output
unit these units are: -
1. Input unit: - When instructions are given the input unit transfers it
to processor and converts it into machine language (Binary Lang.).
2. CPU: - It consists of different path like memory which is also
divided into two paths. These paths are used to store the input
data (Instructions) for short time the memory units uses the short
memory location for storing the input values and their addresses.
These short locations are known as registers.
Page | 1
, There are two types of register:
MAR (Memory address register): It is used to locate the data and
instructions with specific address. When a program is executed
then the read and write operation takes the data from memory by
using their specific address and execute the program.
MBR (Memory buffer register): It is used to store the value for
short time before execution of an operation and after execution
and when result is transferred to selected output unit the MBR
release the value and make the free space for the next
instruction.
3. Input / output AR: - It is used to store the unique address (port
no.) for accepting input and producing output.
4. Input / output BR: - It is used for storing the converted files and it
also store the result converted files for short time. After
displaying the result buffer register release the memory space for
next instructions.
CPU
The CPU is known as processor and it is responsible
for execution of a program, when processor is develop for small
computers the all circuits are combined on single chip which is made
by silicone. The chip is a semiconductor device I which the circuit are
arranged according to different patterns like LSI (Large Scale
Integration) or VLSI (Very Large Scale Integration) in these patterns
thousands of circuits are combined according to user requirement
and device compatibility.
Page | 2
, Input / output unit
ALU
Register System Bus
CU
Memory
Microprocessor: - Microprocessor arranges the all circuits within a
silicon chip in compact forms. The microprocessor perform the basic
functions for execution of program with fast speed it is small in size
but fast in speed.
Microprocessor provides the facility to connect the compatible
multiple input output device.
Microprocessor performs the basic functions for user within three
steps: -
1. Fetched: - When data is input device it is store into registers
for short time. When processor starts the execution it fetched
the input values from memory registers. The whole process of
searching the data is known as Fetching.
2. Decoding: - The fetched instruction changed into machine
language which can be understood by processor. The process
of conversion is called Decoding.
Page | 3
Computer System Architecture
8/1/2023
Notes of CO BCA part 2
Vijay pal
, Unit – 1
Components of Computer
CPU
MAR
RAM
MBR
ROM
Input devices Output devices
Secondary memory
Central Unit
Arithmetic logical unit
Keyboard, Printer,
Mouse, Monitor,
Scanner etc. Speaker etc.
MAR – Memory Address Register
MBR – Memory Buffer Register
A system maintain different units for executing a program or
instructions from input to processing unit and processing unit to output
unit these units are: -
1. Input unit: - When instructions are given the input unit transfers it
to processor and converts it into machine language (Binary Lang.).
2. CPU: - It consists of different path like memory which is also
divided into two paths. These paths are used to store the input
data (Instructions) for short time the memory units uses the short
memory location for storing the input values and their addresses.
These short locations are known as registers.
Page | 1
, There are two types of register:
MAR (Memory address register): It is used to locate the data and
instructions with specific address. When a program is executed
then the read and write operation takes the data from memory by
using their specific address and execute the program.
MBR (Memory buffer register): It is used to store the value for
short time before execution of an operation and after execution
and when result is transferred to selected output unit the MBR
release the value and make the free space for the next
instruction.
3. Input / output AR: - It is used to store the unique address (port
no.) for accepting input and producing output.
4. Input / output BR: - It is used for storing the converted files and it
also store the result converted files for short time. After
displaying the result buffer register release the memory space for
next instructions.
CPU
The CPU is known as processor and it is responsible
for execution of a program, when processor is develop for small
computers the all circuits are combined on single chip which is made
by silicone. The chip is a semiconductor device I which the circuit are
arranged according to different patterns like LSI (Large Scale
Integration) or VLSI (Very Large Scale Integration) in these patterns
thousands of circuits are combined according to user requirement
and device compatibility.
Page | 2
, Input / output unit
ALU
Register System Bus
CU
Memory
Microprocessor: - Microprocessor arranges the all circuits within a
silicon chip in compact forms. The microprocessor perform the basic
functions for execution of program with fast speed it is small in size
but fast in speed.
Microprocessor provides the facility to connect the compatible
multiple input output device.
Microprocessor performs the basic functions for user within three
steps: -
1. Fetched: - When data is input device it is store into registers
for short time. When processor starts the execution it fetched
the input values from memory registers. The whole process of
searching the data is known as Fetching.
2. Decoding: - The fetched instruction changed into machine
language which can be understood by processor. The process
of conversion is called Decoding.
Page | 3
