Computer architecture

Computer Architecture(Basics)
Sunawar Khan Ahsan
IIUI

COMPUTER ARCHITECTURE
TOPICS OF
DISCUSSION:-
DEFINITION HISTORY ROLE I/O DEVICES CPU MEMORY REGISTERS BUS

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.

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.

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.

Von Neumann Architecture
Section 2

Components of computer architecture:-
The important components
I/O Devices
CPU(central
processing
unit)
Memory Register Buses

I/O Devices
 Its stands for Input and Output devices.
 Input devices:
These devices are used to communicate with the computer.
 Output devices:
These devices are used to communicate with the user.

Input devices:
Following are the examples of some input
devices:
Keyboard
Mouse
Joystick
Microphone
Scanner
Bar code reader

Output Devices:
Following are the examples of
some input devices:
Monitor
Speakers
Printers
Projectors

Central Processing Unit
Section 4

CPU:
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
(mother board).
CPU also perform data processing.

CU:
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
cycle.

EXAMPLES:-
A few examples of devices that require a
control unit are CPUs and GPUs.

ALU:
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.

Operations
Operations
Arithmetic
operations.
Logical
operations.

Arithmetic operations:
Followings are some Arithmetic's operators:
Addition
Subtraction
Multiplication
Division

Logical operations:
These
operations
produce results
True
False
There are some
logical
operator:
AND
OR
NOT

Memory:
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.

TYPES :-
Types of Memory
Primary /
Main memory
Secondary Memory
/ Storage devices

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.

Types of Main Memory:
Types of Main
Memory
RAM
(Random Access Memory)
ROM
(Read Only Memory)

RAM:
Main memory is usually referred as RAM.
It is also called volatile, or user memory.
The contents are lost as the electric supply is
cut-off.
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
Windows.

Types of RAM:
Types
• SRAM
• Static Random Access Memory
• DRAM
• Dynamic random Access Memory

SRAM:
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.

DRAM(dynamic random access memory)
It must have an electric current to maintain its
electric states.
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.

ROM:
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
memory.
When the power is switched off the
contents of ROM is not lost.

Types of ROM:
PROM
EPROM
EEPROM

PROM (programmable read only memory)
It is initially blank and the manufacture writes
instruction and data with some special
devices.
Once the information is stored onto PROM
,then it cannot be changed.

EPROM:
It stands for erasable programmable read only
memory.
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.

EEPROM:
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.

Secondary Memory
This is the memory which is used to store the
data permanently.
There are some example of secondary memory:
CD (Compact disk)
Hard disk
Floppy disk
Flash drive

What is virtual memory?
In computing, virtual memory is
a memory management technique
developed for multitasking kernels.

Registers:
These are the high speed memory locations built into
the microprocessor.
It increase the performance of system.

Types of Registers:
PC (Program Counter)
IR (Instruction Register)
MAR (Memory Address Register)
MBR (Memory Buffer Register)
SP (Stack Pointer Register)
GPR (General Pointer Register A,B,C,D)
Address Register (CS, DS, ES, SS)

PC (Program Counter)
It hold the address of the next
instruction to be fetched and
executed.

IR (Instruction Register)
 It hold the current instruction that is being
executed.

MAR (Memory Address Register)
It holds the address of active memory location.

MBR (Memory Buffer Register)
It holds the contents of the memory
location read from or written in the
memory.

SP (Stack Pointer Register)
Arrangement of data is called stack data is
stored in or retrieved from stack using LIFO
(Last in First Out).
LIFO is also known FILO (First in Last Out).

GPR (General Purpose Register)
These registers are used to perform arithmetic
and logical operations.

GENERAL PURPOSES
There are four general purpose register:
Accumulator
Base register
Counter register
Data register

Accumulator:
It is used for Arithmetic and logical
operations.

Base register
 Base register is used for:
 Arithmetic
 Data movement
 Special addressing abilities.

Counter register
As the name show it is used for counting
purpose.
It acts as counter in loop.

Data register
It has special role in division and multiplication.
The size of these registers is from 1 to 4 bytes.

Address Register
It is a group of 4 registers:
 CS (Code Segment)
 DS (Data Segment)
 ES (Extra Segment)
 SS (Stack Segment)

Buses:
These are circuits provide a
communication path between two or
more devices of a digital computer.

All the components of a computer are
connected with a set of parallel lines.
These lines are called BUS.
There are two types of Buses:
System Bus
Expansion Bus

System Bus:
It is divided into three main
categories:
Control Bus
Address Bus
Data bus

Control Bus
These lines are used to transmits the
other control signals from one
component to another.
It also transmits the other control signals
like ACKS (acknowledgement signal).

Address Bus
It carries the address of various memory
locations to perform read and write
operations.
It uses a few system bus lines to specify
the address of destination; these lines are
called address bus.

Data Bus
Data bus is used to transfer the data
from one component to another.
These are 32 or 64 parallel lines reserved
on system bus.

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
system bus.

Computer architecture

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