Presented By
Prof.Y.A.Pathak
Assistant Professor In
Electronics
DEPARTMENT OF PHYSICS
DADA PATIL MAHAVIDYALAYA KARJAT
DATE: 2603/2014

What is a Computer?
 Computer
 Device capable of performing computations and making
logical decisions
 Computers process data under the control of sets of
instructions called computer programs
 Personal computers: economical enough for individual
 Distributed computing: computing distributed over
networks
 Client/server computing: sharing of information across
computer networks between file servers and clients
(personal computers)
Dale Roberts

First generation computers
(1940-1956)
 The first computers used vacuum tubes for circuitry
and magnetic drums for memory.
 They were often enormous and taking up entire room.
 First generation computers relied on machine
language.
 . They were very expensive to operate and in addition
to using a great deal of electricity, generated a lot of
heat, which was often the cause of malfunctions.
 The UNIVAC and ENIAC computers are examples of
first-generation computing devices.

First generation computers

Second generation computers
(1956-1963)
• Transistors replaced vacuum tubes and ushered in the
second generation of computers.
• Second-generation computers moved from
cryptic binary machine language to symbolic.
• High-level programming languages were also being
developed at this time, such as early versions
of COBOL and FORTRAN.
• These were also the first computers that stored their
instructions in their memory.

Second generation computers

Third generation computers
(1964-1971)
 The development of the integrated circuit was the
hallmark of the third generation of computers.
 Transistors were miniaturized and placed
on siliconchips, called semiconductors.
 Instead of punched cards and printouts, users
interacted with third generation computers
through keyboards and monitors and interfaced with
an operating system.
 Allowed the device to run many
different applications at one time.

Third generation computers

Fourth generation computers
(1971-present)
 The microprocessor brought the fourth generation of
computers, as thousands of integrated circuits were
built onto a single silicon chip.
 The Intel 4004 chip, developed in 1971, located all the
components of the computer.
 From the central processing unit and memory to
input/output controls—on a single chip.
 . Fourth generation computers also saw the
development of GUIs, the mouse and
handheld devices.

Fourth generation computers

Fifth generation computers
(present and beyond)
 Fifth generation computing devices, based on artificial
intelligence.
 Are still in development, though there are some
applications, such as voice recognition.
 The use of parallel processing and superconductors is
helping to make artificial intelligence a reality.
 The goal of fifth-generation computing is to develop
devices that respond to natural language input and are
capable of learning and self-organization.

Fifth generation computers

Input Devices
 Input Devices: devices
that input information
into the computer such
as a keyboard, mouse,
scanner, and digital
camera.

Output Devices
 Output: devices that
output information
from the computer such
as a printer and
monitor.

Central Processing Unit
 CPU (Central Processing Unit) also called the
Microprocessor or “The Brain” of the Computer.
 Processor speed: The speed at which a
microprocessor executes instructions. This is usually
measured in megahertz (MHz).
 Brands of Processors include:
 Pentium
 Celeron
 MAC
 AMD
 Cyrix

Central Processing Unit
 Computer chip: also called the
microprocessor may contain an
entire processing unit.
 Computer chips contain millions
of transistors. They are small
pieces of semi-conducting
material (silicon).
 An integrated circuit is embedded
in the silicon. Computers are made
of many chips on a circuit board.

Data Storage Devices
 The hard-drive is a mechanical
storage device typically located
internally.
 Fast recording and recovery of
data
 Large storage capacity
 Magnetic
 Primary storage device for data
and programs
 Speed is measured in R.P.M.’s

Data Storage Devices (cont’d)
 CD-ROM (compact disk read
only memory)
 Approximately 600 to 700
megabyte of storage
 An optical device read by
a diode laser

Data Storage Devices (cont’d)
 Floppy diskette is magnetic
storage device for small
amounts of data (1.44MB).
 FLASH drive is a compact
and portable electronic
storage device.
 USB (plug and play)
supported

Computer Memory
 Computer memory is binary (0 or 1) (on or off).
 The byte is the standard unit of measurement.
 A byte is composed of 8 bits (binary digits).
 Typical units of measurement:
 1 KB (kilobyte) = 1000 bytes
 1 MB (megabyte) =1000 kilobytes or 1 million bytes
 1 GB (gigabyte) =1000 megabytes or 1 billion bytes

Computer Memory
 RAM (random access memory)
stores data that is processing.
This type of memory is erased
when the computer is turned
off.
 ROM (read only memory)
contains special instructions for
the computer to operate.
 Cache memory increases the
speed of the processor by
recording and anticipating
instructions.

Resolution
 Screen resolution is measured in pixel per
inch (ppi), and printer resolution is
measured in dots per inch (dpi).
 Computer screen resolution is approximately
72 ppi.
Width x Height (Pixels) Video Display
640 x 480 Low Resolution
800 x 600 Medium Resolution
1600 x 1200 High Resolution

HARDWARE AND SOFTWARE

Software
 Program
 a sequence of instructions to accomplish a result
 a computer processes information under the direction of
a program
 Data
 information to be processed by a program
 Example
 Data: for each employee, the employee number, hours
worked & hourly pay rate
 Program: instructions on how to process the data to
produce pay cheques, payroll register, etc.

Central
Processing
Unit
Main
Memory
Floppy Disk
Hard Disk
Monitor
Keyboard
A simplified view of a computer
system

Hardware Devices
 Input Devices (Get information)
 Keyboard
 Mouse
 Scanner
 Output Devices (Give information)
 Screen/monitor
 Printer

Hardware Devices
 Processing Device (Arithmetic/logic/repetition)
 Central Processing Unit (CPU)
 286, 386, 486, Pentium, K5, K6
 Has three basic parts
 Arithmetic Logic Unit (ALU)
 executes all the arithmetic and logic instructions
 Control Unit
 decodes instructions and determines which is next to be
executed
 Buses/Registers
 Buses are paths for information entering/exiting the CPU
 Registers are memory for processing information

The Central Processing Unit
 The CPU continuously follows the fetch-
decode-execute cycle:
fetch
Retrieve an instruction from main memory
decode
Determine what the
instruction is
execute
Carry out the
instruction

Hardware Devices
 Storage
 Two types
 Primary and secondary
 Primary Storage (main memory)
 On board memory (located on the motherboard)
 Very fast, but expensive
 Two types
 RAM – Random Access Memory
 ROM – Read Only Memory

Hardware Devices
 RAM - Random Access Memory
 Read/write capability
 Contents lost when computer is turned off (volatile)
 A program must be in RAM for it to execute
 128 to 256MB for a typical desktop computer

Hardware Devices
 ROM - Read Only Memory
 Read but not write capability
 Permanent (non volatile)
 Stores the preliminary instructions to be executed when
the computer is turned on, for example
 To check RAM
 To check communications with peripheral devices
 Bootstrap loader program

Hardware Devices
Address
9278
9279
9280
9281
9282
9283
9284
9285
9286
Large values are
stored in consecutive
memory locations
10011010
Each memory cell stores a
set number of bits (usually 8
bits, or one byte)
Content
Main memory is
divided into
many memory
locations (or
cells)
Each memory cell has a
numeric address, which
uniquely identifies it

Hardware Devices
 Secondary Storage (secondary memory)
 External devices (not on the motherboard); either
inside or outside the computer
 Store programs and data permanently
 Slower, but cheaper
 RAM - nanoseconds, Drive - milliseconds
 Different sizes/styles
 Floppy Disk - 1.4MB (portable)
 Zip Drive - 100-750MB (portable)
 CD - 650MB (portable)
 Jaz Drive – 1-2GB (portable) discontinued
 Hard Disk Drive >=20GB (not portable)
 Tape - 50GB (portable, very slow)
 Flash drives (portable)

Hardware Devices
 Other devices
 Port
 For connecting peripheral devices
 USB, Parallel and serial ports
 Modem (internal or external)
 For communicating over telephone lines

Software
 A computer program is a series of instructions
 each instruction is expressed in a format consistent with
a predefined set of rules
 a computer processes data under the direction of the
instructions in a program
 there are instructions to input, process, store and output
data
 the user of a program (as distinct from its creator) has
no need to be aware of the details of its construction
 the user is only interested in the services that the
program is able to provide

Software
 Programming Languages
 1st generation
 machine language
 instructions coded using combinations of 0’s & 1’s
 2nd generation
 assembly languages (low-level symbolic languages)
 instructions coded using letters & numbers
 one assembly language instruction is translated into one
machine language instruction

Software
 Programming Languages
 3rd generation
 high-level symbolic languages
 one instruction generates multiple machine language
instructions
 4th generation programming languages
 non-procedural languages
 code “what” not “how”

Software
HIGH LEVEL ASSEMBLY MACHINE
z = x + y MOV AL, X 0010 1001 0001
MOV AH, Y 0010 1100 0010
ADD AL, AH 0100 0001 0010
MOV Z, AL 0010 0010 1011

Software categories
 Operating System
 controls all machine activities
 provides the user interface to the computer
 manages resources such as the CPU and memory
 Windows XP, Unix, Linux, Mac OS
 Application program
 generic term for any other kind of software
 word processors, games, . . .
 Most operating systems and application programs have a
graphical user interface (GUI)

Software
 Operating Systems
 The most important software on a computer
 always running to perform the following tasks
 create and manage files
 run programs
 control information going to/from the peripherals
 Eg: MS-DOS
 create and manage files - several programs
 run programs - COMMAND.COM
 peripherals - IO.SYS, MSDOS.SYS

Additional COMPUTER CONCEPTS

An electronic device, operating under the control of
instructions stored in its own memory unit, that can
accept data (input), manipulate the data according
to specified rules (process), produce information
(output) from the processing, and store the results
for future use.

What does a computer do?
 Input
 Process
 Output
 Storage
Processor
Control Unit/Arithmetic Logic
Unit
Memory
Storage Devices
Input
Device
s
Output
Devices

Input Devices
Any hardware component that allows you
to enter data, programs, commands, and
user responses into a computer
Input Device
Examples
 Keyboard
 Mouse

Output Devices
 Output devices make the information resulting from
processing available for use
 Output Device Examples
 Printers
 Impact
 Nonimpact
 Photo
 Display Devices
 CRT
 LCD

Storage Devices
 Removable
 Floppy disk, or diskette
 Compact Disc CD-R, CD-RW, CD-
ROM
 DVDs – DVD-ROM, DVD-R, DVD-
RW, DVD-RAM
 Zip disk
 Flash disk/USB drive
 Tape
 Non-Removable
 Hard disk

System Unit
 The motherboard, or system board, is the main circuit
board of the system unit
 The processor, also called the central processing unit
(CPU), interprets and carries out the basic instructions
that operate a computer
 The control unit interprets the instructions
 The arithmetic/logic unit (ALU) performs the logical and
arithmetic processes
 Memory, also called random access memory, or RAM,
consists of electronic components that store data,
instructions, and information, as needed by the
processor

Types of Computers
Supercomputers
and Mainframes
Microcomputers
 Desktops
 Laptops (Notebooks)
 Handhelds