4. Computer architecture??
Computer architecture is the conceptual
design and fundamental operational
structure of a computer system.
The design made a clear distinction
between architecture and implementation,
allowing IBM to release a suite of
compatible designs at different prices.
5. History of computer architecture:-
• The term architecture as applied to computer
design, was first used in 1964 by Gene Amdahl, G.
Anne Blaauw, and Frederick Brooks, Jr., the
designers of the IBM System/360.
• They joined the term to refer to those aspects of
the instruction set available to programmers,
independent of the hardware on which the
instruction set was implemented.
7. Role of Computer Architecture:-
The coordination of abstract levels of a
processor under changing forces, involving
design, measurement and evaluation.
It also includes the overall fundamental
working principle of the internal logical
structure of a computer system.
12. I/O Devices
Its stands for Input and Output devices.
These devices are used to communicate with the computer.
These devices are used to communicate with the user.
Central processing unit (CPU) is the portion of
a computer system that carries out
the instructions of a computer program, to
perform the basic arithmetical, logical,
and input/output operations of the system.
The CPU plays a role somewhat analogous to
the brain in the computer.
CPU is a small chip mounted on the circuit board
CPU also perform data processing.
It stands for “Control Unit”.
A control unit in general is a central part of
the machinery that controls its operation.
The CU reads the instruction from memory,
decodes and executes these instructions.
Its is also known as fetch-decode and execute
Its stands for “Arithmetic and Logical Unit”.
An arithmetic-logic unit (ALU) is the part of a
computer processor (CPU) that carries out
arithmetic and logic operations on the operands
in computer instruction words.
It is the very important part of any system.
The term memory identifies data storage that
comes in the form of chips, and the
word storage is used for memory that exists
on tapes or disks.
Some computers also use virtual memory.
28. Main Memory:
It is called working area of computer.
Refers to physical memory that is
internal to the computer.
Another term for main memory is RAM.
Computer cannot work without it.
29. Types of Main Memory:
Types of Main
(Random Access Memory)
(Read Only Memory)
Main memory is usually referred as RAM.
It is also called volatile, or user memory.
The contents are lost as the electric supply is
One of the first home computer used 64
kilobytes of RAM memory but today’s modren
computers need a minimum of 64 MB
(recommended 128 MB or more)to run a
Its stands for static random access memory.
No refreshing of electric states is required in SRAM.
These chips are faster than DRAM.
• Static random-access memory (SRAM) is a type
of semiconductor memory.
34. DRAM(dynamic random access memory)
It must have an electric current to maintain its
Its design is less complex than SRAM.
Dynamic random-access memory (DRAM) is a
type of random-access memory that stores
each bit of data in a separate capacitor within
an integrated circuit.
It is obvious from name that the
contents of ROM are read only.
New data can not be written on it.
Its contents are permanent.
It is referred to non-volatile or system
When the power is switched off the
contents of ROM is not lost.
39. PROM (programmable read only memory)
It is initially blank and the manufacture writes
instruction and data with some special
Once the information is stored onto PROM
,then it cannot be changed.
It stands for erasable programmable read only
It is another type of ROM chip and it is possible
to erase the stored information and the chip can
be reprogrammed using special devices.
Information can be erased using ultraviolet rays.
It stands for electrically erasable
programmable read only memory.
It is a kind of ROM chip can be re-written
using electrical devices.
The stored information on EEPROM can be
erased, modified or reprogrammed easily
using special devices.
42. Secondary Memory
This is the memory which is used to store the
There are some example of secondary memory:
CD (Compact disk)
43. What is virtual memory?
In computing, virtual memory is
a memory management technique
developed for multitasking kernels.
65. Address Bus
It carries the address of various memory
locations to perform read and write
It uses a few system bus lines to specify
the address of destination; these lines are
called address bus.
69. Expansion Bus:
The major components are connected to
the system bus and the remaining
components are connected to another
bus called expansion bus and the
expansion bus is connected to the