5. CPU AND HOW IT
WORKS
Central Processing Unit performs the actual
computation inside any computer.
It is a microprocessor made up of millions of
microscopic transistors embedded in a circuit
on a silicon wafer or chip.
This microprocessor has different parts which
perform different functions.They are the
control unit,the arithmetic logic unit,the
registers,the caches,the primary storage,the
secondary storage and various output devices.
6. CPU AND HOW IT
WORKS(contd)…………
The control unit sequentially accesses
program instructions,decodes them and
controls the flow of data to and from
the ALU and all the other parts of the
microprocessor.
The ALU performs the mathematic
calculations and makes logical
comparisons.
The registers are high-speed storage
areas that store very small amounts
data for short periods of time.
7. CPU AND HOW IT
WORKS(contd)…………
The inputs are brief instructions about what to do with the
data.These instructions come from software in other parts of
the computer.Data might be inputted via a keyboard or read
from a file.The inputs are stored in registers until they are
sent to the next step in the processing.
Data and instructions travel in the chip via electrical pathways
called the buses.
The control unit directs the flow of data and instructions
within the chip.
Data and instructions translated into binary form are received
by the ALU from the registers to make the desired
computation.
The data in their original form and the instructions are sent
the storage registers and then are sent back to a storage
place outside the chip such as the hard drive.Meanwhile,the
transformed data go to another register and then onto other
parts of the computer.
8. COMPUTER MEMORY
Memory Capacity-All data are translated through
computer languages into series or binary digits or bits.A
particular combination of bits represent a certain
alphanumeric character.8 bits are needed to represent
anyone of these characters.This 8-bit string is known
as a byte.
The hierarchy of the byte memory capacity is as
follows:
Kilobyte-A kilobyte is 1024 bytes(210
) bytes.
Megabyte-One megabyte is approximately one million
bytes(1024*1024=10,48,576 bytes).e.g.RAM
Gigabyte-One gigabyte means one billion
bytes(1024*1024*1024 bytes).e.g Secondary Storage-
Hard Drive.
Terabyte-One trillion bytes is a terabyte.
9. PRIMARY STORAGE
It is also called the main memory.
It stores 3 types of information for very brief
periods of time.These information include data
to be processed by the CPU,instructions for
the CPU as to how to process the data and
operating system programs that manage various
aspects of the computer’s operation.
Primary storage takes place in chips mounted
on the computer’s main circuit
board(motherboard) located as physically close
as possible to the CPU chip.
10. TYPES OF PRIMARY
STORAGE
Registers-they are a part of the
CPU.They have the least capacity
storing extremely limited amounts
of instructions and data only
immediately before and after
processing.
11. TYPES OF PRIMARY
STORAGE(contd)…….
Random Access Memory(RAM)-It stores more
information than the registers and is far away from the
CPU.When you start a software program on your
computer the entire program is brought from the
secondary storage into the RAM.As the program is run
small parts of the program’s instructions and data are
sent to the registers and then to the CPU.
Ram is temporary and volatile.RAM chips loose their
contents if the power is turned off.RAM chips are
located directly on the computer’s main circuit board or
in other chips located on peripheral cards that are
plugged into the main circuit board.
2 main types are dynamic RAM(DRAM) and static
RAM(SRAM).The former offers the greatest capacities
and lowest cost per bit but are relatively slow.The
latter are more expensive and has a high level of
performance.
12. TYPES OF PRIMARY
STORAGE(contd)…….
Read-only-Memory(ROM)-Here certain critical
instructions are safe guarded.ROM is non
volatile and retains these instructions even
when the power is turned off.
Read only means that the instructions can only
be read by the computer but cannot be
changed by the user.Example of such
instructions are those that are needed to boot
the computer once it is shut off.
ROM chips that can be programmed are called
the programmable ROM(PROM),and some that
can be erased and rewritten are known as
erasable programmable ROM(EPROM).
13. SECONDARY STORAGE
It is designed to store large amounts of data for
extended periods of time.It can have a memory capacity
of several terabytes.
It is non-volatile.
It takes much more time to retrieve data from the
secondary storage than the RAM because of the
electromechanical nature of the secondary storage
devices.
It can take place on a variety of media each with its
own technology.
It ensures increased portability,more direct-access
methods and higher capacity with lower costs.
14. TYPES OF SECONDARY
STORAGE
Magnetic Media-Magnetic Tape is kept on a large open
reel or in a smaller cartridge or cassette.This is the
cheapest storage medium and can handle enormous
amounts of data.It is the slowest retrieval of data
because all data are placed on the tape sequentially.
Sequential access means that the system has to run
through the entire tape before it comes to the desired
piece of data.
Magnetic media store information by giving tiny particles
of iron oxide embedded on the tape a positive or a
negative polarization which corresponds to the binary ‘0’
and ‘1’ respectively.
15. TYPES OF SECONDARY
STORAGE(contd)……..
Magnetic disks allow more rapid access to the
data than the magnetic tape.They are known
as hard disks and are the most commonly used
mass storage devices because of their low cost
high speed and larger storage capacity.
These disk drives store data on platters
divided into concentric tracks.Each track is
then divided into segments called sectors.To
access a given sector a read/write head pivots
across the rotating disks to locate the right
track,calculated from an index table and the
head then waits as the disk rotates until the
right sector is below it.
16. TYPES OF SECONDARY
STORAGE(contd)……..
Any piece of data can be retrieved by a non-sequential
manner that is by direct access.The read/write heads
use the data’s address to quickly find and read the
data.
Here data access is very fast usually in the order of
milliseconds.Thus these drives are very popular.But they
are susceptible to mechanical failures.
Disk Drive Interfaces-They are faster.Most personal
computers and work stations use one of the two high-
performance disk interface standards:Enhanced
Integrated Drive Electronics(EIDE) or Small Computer
Systems Interface(SCSI).The former offers good
performance and is inexpensive.The latter is more
expensive but offer a more faster interface and
support.
17. TYPES OF SECONDARY
STORAGE(contd)……..
Magnetic Diskettes-They are commonly known
as floppy disks.They function similarly to hard
drives but with some key differences.
They are much slower and have much less
capacity ranging from 1.44 mega bytes to 250
mega bytes.
They are portable unlike the hard disk drives
which are permanently installed in a computer.
18. TYPES OF SECONDARY
STORAGE(contd)……..
Optical Storage Devices-They do not store data via
magnetism.A pinpoint laser beam is used to burn tiny
holes into the surface of a reflective plastic platter to
record information.
When the information is read,another laser installed in
the optical disk drive of the computer shines on the
surface of the disk.If light is reflected that
corresponds to one binary state.If the light shines on
one of the holes burned by the recording laser,there is
no reflection and the other binary state is read.
Compared to magnetic media these drives are slower.But
they are much less susceptible to damage from
contamination and are also less fragile.
19. TYPES OF SECONDARY
STORAGE(contd)……..
Optical disk storage systems can be used can
be used for large capacity data storage.These
technologies known as optical juke boxes store
many disks and operate much like the
automated phonograph record changers.
Types of optical disks include compact disk
ROM(CD-ROM),digital-video-disk(DVD) and
fluorescent multi layer disk(FMD-ROM).
Other secondary storage devices include
memory cards and expandable storage devices
that is the removable disk cartridge.
20. ENTERPRISE STORAGE
SYSTEMS
It is an independent,external system
with intelligence that includes two or
more storage devices.They are an
alternative to allowing each host or
server to manage its own storage
devices directly.
These provide large amounts of
storage,high-performance data
transfer,a high degree of
availability,protection against data loss
and sophisticated management looks.
21. TYPES OF ENTERPRISE
STORAGE SYSTEMS
Redundant Array of Independent Disks-Hard
drives in all computers are susceptible to
failures caused by temperature variations,head
crashes,motor failure,controller failure and
changing voltage conditions.To improve
reliability and protect the data many
computers use redundant array of
disks(RAIDS) storage products.
Network Attached Storage-It is known as
NAS.This device is a special purpose server
that provides file storage to users who access
the device over a network.This server is simple
to install i.e. plug-and-play and works exactly
like a general purpose file server.
22. TYPES OF ENTERPRISE STORAGE
SYSTEMS(contd)……
Storage Area Network-It is known as SAN.It
is an architecture for building
special,dedicated networks that allow rapid and
reliable access to storage devices by multiple
servers.
Storage over IP is a technology that uses the
Internet Protocol to transport stored data
between devices within a SAN.Storage
Visualization S/W is used with SANs to
graphically plot an entire network and allow
storage administrators to view the properties
of and monitor all devices from a single
console.
23. COMPUTER HIERARCHY
Supercomputers-They are the fastest
computing engines available at any given
time.They generally address computationally
demanding tasks on very large data sets.
They run military and scientific
applications,although their use for commercial
applications such as data mining has been
increasing.
They operate generally 4 to 10 times faster
than the next most powerful computer class
that is the mainframe.Supercomputers help in
analyzing the earth’s crust.
24. COMPUTER
HIERARCHY(contd)……
Mainframe Computers-They are a distinct
class of systems differentiated by H/W and
S/W features.
They are popular in large enterprises for
extensive computing applications that include
airline reservation systems,corporate
payroll,student grade calculation and reporting.
They are less powerful and less expensive than
the supercomputers.IBM calls its mainframe
computer services the eServer zSeries.
Example is the Merrill Lynch’s online
information and customer service.
25. COMPUTER
HIERARCHY(contd)…..
Midrange Computers-They are of two types,the
minicomputers and the servers.The former are relatively
small,inexpensive and compact computers that perform
the same functions as the mainframe computers but to
a more limited extent.They are designed to accomplish
specified tasks such as process control,scientific
research and engineering applications.
Larger companies gain greater corporate flexibility by
distributing data processing with minicomputers in
organizational units instead of centralizing computing at
one location.They meet the needs of smaller
organizations.IBM is the market leader in minicomputers
with its eServer iSeries(formerly the AS/400).
26. COMPUTER
HIERARCHY(contd)…..
Smaller types of midrange computers,called
servers typically support computer
networks,enabling users to share
files,software,peripheral devices and other
network resources.They have large amounts of
primary and secondary storage and powerful
CPUs.
They provide the hardware for e-
commerce.They deliver Web pages and process
purchase and sales transactions.As companies
pack greater number of servers in their
server farms,they are using pizza-box-size
servers called rack servers.
27. COMPUTER
HIERARCHY(contd)…..
Workstations-They were developed originally
to provide high levels of performance
demanded by engineers.They run
computationally intensive scientific,engineering
and financial applications.
They are typically based on RISC (reduced
instruction set computing)architecture and
provide both very high speed calculations and
high-resolution graphic displays.
These applications include electronic and
mechanical design,medical imaging,scientific
visualization,3-D animation and video editing.
28. COMPUTER
HIERARCHY(contd)…..
Microcomputers-They are also called
micros,personal computers or PCs.
They are the smallest and least
expensive category of general-purpose
computers.
They can be subdivided into 4
classifications based on their
size:desktops,thin clients,notebooks and
laptops,mobile devices.
29. COMPUTER
HIERARCHY(contd)…..
Desktop PCs-This has become the
dominant method of accessing workgroup
and enterprise wide applications.It is
usually modular in design with separate
but connected monitor,keyboard and
CPU.
Most desktop systems currently use
Intel 32-bit technology running some
version of windows.The exception is the
Apple Macintosh which runs Mac OS on
a PowerPC processor.
30. COMPUTER
HIERARCHY(contd)…..
Thin-client Systems-These are desktop computer
systems that do not offer the full functionality of a
PC.They are less complex because they lack locally
installed software and are thus easier and less
expensive to operate and support than PCs.
The benefits include fast application
deployment,centralized management,lower cost of
ownership and easier
installation,management,maintenance and support.
The disadvantages include user resistance and the need
to upgrade servers and buy additional server applications
and licenses.One type of thin client is the terminal
allowing the user to only access an application running on
a server.
31. COMPUTER
HIERARCHY(contd)…..
Laptop and notebook Computers-As
computers become much smaller and
more powerful they become
portable.They are small,easily
transportable,light weight
microcomputers that fit easily into a
briefcase.
They are designed for maximum
transportability allowing access to
processing power and data outside an
office environment.
32. COMPUTER
HIERARCHY(contd)…..
Mobile Devices-Emerging platforms for
computing and communications include such
mobile devices as handheld computers often
called personal digital assistants (PDAs) and
mobile phone handsets with new wireless and
internet access capabilities.
Mobile devices have the following
characteristics:
They cost much less than PCs.
Their OS s are much simpler.
They provide both computer and/or
communications features.
They offer a web portal that is viewable on a
33. COMPUTER
HIERARCHY(contd)…..
Embedded Computers-These are
micro-processors that are built
into various industrial and consumer
products.They are usually
dedicated to specific tasks and
most of the data that they use will
come from sensors rather than a
keyboard or mouse.
