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Care for network and computer hardware

1. Overview hardware and software

As you know, a computer is made up of hardware and software. In some ways the analogy
can be made to humans that the hardware is your body and the software is your mind. If
the processor is the computer's "brain" then the software is what that brain "thinks". Each
and every thing that happens inside the computer is controlled by some form of software:
from the high level spreadsheets, games and other applications, to the low-level device
drivers that tell your hardware exactly what it has to do to make them work properly.

1.1 External hardware components

One of the great strengths of the PC platform, which has led to its overwhelming success in
the marketplace, is its modularity. Most PCs are made up of many different individual
components, which can be mixed and matched in thousands of different configurations. This
lets you customize the PC you either buy or build to meet your exact needs. The picture
below identifies the most common external hardware components of hardware.

External view of a complete, modern PC system.

1.2 Internal components of PC hardware

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This section discusses some of the major components of a typical, modern PC. Some PCs
have some of these combined into one physical unit, but inside, somewhere, you'll find most
if not all of these pieces. (Most modern PCs also have components not listed here; )

System Case

 System units may be packaged in a number of standard case designs.

 The key characteristics for case design include mounting methods for components,
ventilation characteristics, drive capacity, and footprint (desk space they take up).

 The most familiar PC case style is probably the desktop case design.
 These cases are designed to set horizontally on the desk (hence the name).

 Variations of the basic desktop design include narrow cases, referred to as baby AT
cases, and short desktops, called low-profile cases.

 Tower cases sit vertically on the floor beneath the desk. This case design came
about to free up workspace on the desktop.

 Tower cases offer extended drive bay capacities that make them especially useful
in file server applications where many disk, CD-ROM, and tape drive units may be
desired.

 Although tower designs are convenient, their ventilation characteristics tend to be

poor. Adapter cards are mounted horizontally in tower units and the heat produced
by the lower cards must rise past the upper cards, adding to their heat buildup. To

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compensate for this problem, most tower cases include a secondary fan unit to
increase airflow through the case and thereby dissipate more heat.

 Mini towers and mid towers are short towers designed to take up less vertical space.

 Full towers are common in server machines.

Power supply

Your computer is obviously an electronic device, and its many components of course require
power. Like the case, most people don't give much thought to the power supplied to the
system.

There are two aspects to power in the PC:

 External Power: External power refers to the power that is delivered to the back
of the system case.
 Power Supply: The power supply is the small box that sits inside your case and takes
the external power you supply to the computer. Its main job is to transform this
power into a form the rest of the computer can use.

Care for power supply:

The following is a list of PC problems that often are related to the power supply:

■ Any power-on or system startup failures or lockups

■ Spontaneous rebooting or intermittent (irregular) lockups during normal operation

■ Hard disk and fan simultaneously failing to spin (no +12v)

■ overheating due to fan failure

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■ Small brownouts that cause the system to reset

■ Electric shocks felt on the system case or connectors

■ Slight static discharges that disrupt system operation

■ System that is completely dead (no fan, no cursor)

■ Smoke

■ Blown circuit breakers

Following is a common power supply–related problems:

1. Check the AC power input. Make sure the cord is firmly seated in the wall socket
and in the power supply socket. Try a different cord.

2. Check the DC power connections. Make sure the motherboard and disk drive
power connectors are firmly seated and making good contact. Check for loose
screws.

3. Check the DC power output. Use a digital multimeter to check for proper
voltages. If it’s below spec, replace the power supply.

4. Check the installed peripherals. Remove all boards and drives and retest the
system. If it works, add items back in one at a time until the system fails again. The
last item added before the failure returns is likely defective.

Power protection devices:

■ Surge suppressors

■ Phone-line surge protectors

■ Line conditioners

■ Uninterruptible power supplies (UPS)

 Surge suppressors - can absorb the high-voltage transients produced by nearby

lightning strikes and power equipment.

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 Limited protection
 Surge protector: In addition to protecting the power lines, it is critical to provide
protection to your systems from any connected phone lines.

In many areas, the phone lines are especially susceptible to lightning strikes, which
are the leading cause of fried modems and damage to the computer equipment
attached to them

 Line condition (Stabilizer):It filters the power, bridges brownouts, suppresses

high-voltage and current conditions, and generally acts as a buffer between the
power line and the system.
 A line conditioner provides true power conditioning and can handle myriad problems.
 It contains transformers, capacitors, and other circuitry that can temporarily
bridge a brownout or low-voltage situation.
 Uninterruptable Power Supply:-the best overall solution to any power problem
 UPSes are known as online systems because they continuously function and supply
power to your computer systems.
 In a true UPS, your system always operates from the battery. A voltage inverter
converts from 12v DC to 110v AC. You essentially have your own private power
system that generates power independently of the AC line.
 UPS cost is a direct function of both the length of time it can continue to provide
power after a line current failure and how much power it can provide.

Motherboard and System Devices

The motherboard is the base of the modern computer system. It is amazing how little
attention this critical component gets in mainstream circles, considering how much it does--
though this situation is now improving, fortunately. If the processor is the "brain" of the
computer, then the motherboard is the central nervous system and circulatory system, plus
much more, all rolled into one. Here are the main parts of the motherboard and its related
devices:

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 Motherboard: The motherboard is the main circuit board in the computer where
everything comes together. This is where you plug in your processor, memory, cache,
video card and other cards. It is also where you connect your peripherals.
 System Chipset and Controllers: The chipset is to direct traffic and control the
flow of information inside the computer.
 System Buses: The system buses are the electrical channels through which various
parts of the computer communicate. It is over the system buses that your video
card gets information from the processor, the processor saves data to your hard
disk, etc.
 BIOS: The system BIOS (which stands for Basic Input/Output System and is
pronounced "bye-oss" or "bye-ose") to act as an intermediary between your system
hardware (the chipset, motherboard, processor and peripherals) and your system
software (the operating system).
 Cache: The system cache is a small, high-speed memory area that is placed between
the processor and the system memory. The value of the cache is that it is much
faster than normal system memory.

Basic Electrical Components

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There are several important basic electrical components that are commonly found in the
circuits of virtually all PC parts and peripherals. These devices are the fundamental building
blocks of electrical and electronic circuits, and can be found in great numbers on
motherboards, hard disk logic boards, video cards and just about everywhere else in the PC,
including places that might surprise you.

There are many variants of each of the components shown below; so the diagrams should
only be considered examples.

 Battery: A direct current electricity source of a specific voltage, used primarily in

small circuits.

  

A battery (in this case, a button cell on a PC motherboard.)

 Resistor: As you could probably guess from the name, a resistor increases the
resistance of a circuit. The main purpose of this is to reduce the flow of electricity
in a circuit.

  

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 Capacitor: A capacitor is a component made from two (or two sets of) conductive
plates with an insulator between them. The insulator prevents the plates from
touching.

  

 Inductor: An inductor is essentially a coil of wire. When current flows through an

inductor, a magnetic field is created, and the inductor will store this magnetic
energy until it is released. In some ways, an inductor is the opposite of a capacitor.

Capacitors block DC current and let AC current pass, while inductors do the
opposite.

  

 Transformer: A transformer is an inductor, usually with an iron core, that has two
lengths of wire wrapped around it instead of one. The two coils of wire do not
electrically connect, and are normally attached to different circuits. One of the
most important components in the world of power, it is used to change one AC
voltage into another.

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 Diode / LED: A diode is a device, typically made from semiconductor material, that
restricts the flow of current in a circuit to only one direction.

Fuse: A fuse is a device designed to protect other

components from accidental damage due to excessive
current flowing through them. Each type of fuse is
designed for a specific amount of current.

  

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Jumpers

Jumpers are small devices that are used to control the operation of hardware devices
directly, without the use of software.

A jumper consists of two primary components:

 Jumper: The jumper itself is a small piece of plastic and metal that is placed across
two jumper pins to make a connection, or removed to break a connection. They come
in a few standard sizes (and some non-standard ones I'm sure); only one or two sizes
are commonly seen on PCs. Jumpers are sometimes also called shunts.
 Jumper Pins: A set of pins, across two of which a jumper is placed to make a
specific connection.

1.4 relationship between Hardware and software

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2. Occupational health and safety (OHS)

Organizations will develop procedures for safe working practices as a tool for implementing
their OH&S policies and training staff.

Computer hardware devices and consumables such as printer paper boxes can be very heavy
and care should be taken when manually handling these objects. Manual handling is one of
the most common causes of accidents in the workplace.

Manual handling is defined as:“any activity that involves lifting, lowering, carrying, pushing,
pulling, holding or restraining. It may also include stretching, bending, sustained and
awkward postures, and repetitive movements.”

Recommendations on practices to reduce the risk of manual handling injury at work include:

 hold the load close to your body

 store loads close to where they will be used
 store heavy loads near waist height
 use mechanical aids such a trolley when lifting heavy loads
 don’t lift heavy loads when sitting down

Regardless of the industry in which you work, there are legal requirements that insist on
establishing a safe work environment.

The fundamental purpose of Health and Safety legislation is to:

 secure and promote the health, safety and welfare of people at work

 protect people at a place of work against risks to health and safety arising out of any
activities of people at work

 promote a safe and healthy environment for people at work that protects them from
injury and illness and that is adapted to their physiological and psychological needs

 provide for consultation and cooperation between employers and workers in achieving
the above

 ensure that risks to health and safety at a place of work are identified, assessed and
eliminated or controlled

 develop and promote community awareness of occupational health and safety issues

 provide a legislative framework that allows for progressively higher standards of

occupational health and safety to take account of changes in technology and work
practices

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 Protect people (whether or not at a place of work) against risks to health and safety
arising from the use of machinery that affects public safety.

Safe electrical work practices:

Computer hardware should be located close to a suitable electrical outlet and free from any
other hazards. The use of long extension cords is a trip hazard. If no power outlet is
available, a new fixed power outlet may need to be installed. At work place every one of as
take care of ourselves and the material

Key terms at workplace and OHS

Access control list A list of permissions for objects such as files or folders. These permissions will
(ACL) determine the level of access that a user or group has to an object.

Ambient temperature The temperature of the surrounding environment.

A backup copies files to a second medium such as disk or tape as a precaution in case the
Backup
first medium fails.

The requirements that need to be met, so that a business can perform the required
Business requirements
business tasks.

Materials which are used up and need continuous replenishment, such as printer paper
Consumables
and toner.

Diagnostic testing The testing performed to establish the likely cause of a problem.

Electrostatic discharge The release of static electricity.

Environmental Conditions such as temperature, humidity and air quality which need to be considered,
conditions when locating computer hardware.

Ergonomics The study of the work environment in relation to the user.

The hardware or software device designed to block unauthorized access, to or from a

Firewall
private computer network.

Hazard A situation or substance which could cause injury or illness.

Interoperability The ability of a computer system to work with another computer system.

Maintenance schedule A list of planned maintenance tasks.

Any activity that involves lifting, lowering, carrying, pushing, pulling, holding or
Manual handling
restraining.

Redundancy Having a secondary peripheral computer system or network device which takes over

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when the primary unit fails.

Surge protector A device designed to protect against electrical surges and spikes.

Uninterruptible Power
A device designed to protect against electrical power blackouts.
Supply (UPS) 

3. Monitor treat to network

3.1 system security

Computer security covers a lot of territory: locking your computer room and your machine,
protecting your login accounts with passwords, using file protection to keep your data from
being destroyed, encrypting network communications lines, and using special shields to keep
electromagnetic emanations from leaking out of your computer. But when people talk about
computer security, they usually mean what in this chapter we call computer system security.

computer system security ensures that your computer does what it's supposed to do–even if
its users don't do what they're supposed to do. It protects the information stored in it
from being lost, changed either maliciously or accidentally, or read or modified by those not
authorized to access it.

There are four primary methods to protect the system security:

1. System Access Controls. Ensuring that unauthorized users don't get into the
system, and by encouraging (and sometimes forcing) authorized users to be
security-conscious–for example, by changing their passwords on a regular basis.
2. Data Access Controls.
Monitoring who can access what data, and for what purpose.
3. System and Security Administration.
Performing the offline procedures that make or break a secure system–by clearly
delineating system administrator responsibilities, by training users appropriately,
and by monitoring users to make sure that security policies are observed.
4. System Design.
Taking advantage of basic hardware and software security characteristics; for
example, using a system architecture that's able to segment memory, thus isolating
privileged processes from non privileged processes.

Some of the most common network problems or attacks are:

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 Denial of service  Worms  Packet replay
attacks
 Intrusion attacks  Trojan horses  Password
cracking
 Social  Packet
engineering modification  E-mail cracking

 Viruses

3.2 software security

Security means “The protection of the system against threats using both technical and
administrative controls”. Security encompasses hardware, software, people and data. To
effectively implement security requires appropriate controls, and these controls should
implement specific policy statements that have been dictated by the requirements of the
system, the needs of the organization and any legal constraints. We consider database
security in relation to the following situation:
 Theft and fraud,
 Loss of confidentiality (secrecy),
 Loss of privacy,
 Loss of availability.

For security we need

 Computer-Based Controls
 Non-Computer-Based Controls

1. Computer-Based Controls

Computer-based controls those are available, in the operating system. We focus on

computer-based security controls, with the assumption that we are dealing with a multi-user
environment. Typically, not all of these controls will be available in the PC environment. We
consider:

 Authorization
 Backing-up
 Encryption

Authorization

The granting of a right or privilege which enables a subject to legitimately have access to a
system or object.

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Backing-up

The process of periodically taking a copy of the database and journals (and possibly
programs) onto offline storage media.

It is always advisable to have a backup copy of the database taken at regular intervals ad
kept in secure location.

Encryption

The encoding of the data by a special algorithm those render the data unreadable by any
program without the decryption key.

3.3. security strategies

The security methodology or strategies described in this document is designed to help

security professionals develop a strategy to protect the availability, integrity, and
confidentiality of data in an organization's information technology (IT) system. It will be of
interest to information resource managers, computer security officials, and administrators,
and of particular value to those trying to establish computer security policies. The
methodology offers a systematic approach to this important task and, as a final precaution,
also involves establishing contingency plans in case of a disaster.

Data in an IT system is at risk from various sources—user errors and malicious and non-
malicious attacks. Accidents can occur and attackers can gain access to the system and
disrupt services, render systems useless, or alter, delete, or steal information.

IT system may need protection for one or more of the following aspects of data:

 Confidentiality. The system contains information that requires protection from

unauthorized disclosure. Examples: Timed dissemination information (for example,
crop report information), personal information, and proprietary business
information.
 Integrity. The system contains information that must be protected from
unauthorized, unanticipated, or unintentional modification. Examples: Census
information, economic indicators, or financial transactions systems.

 Availability. The system contains information or provides services that must be

available on a timely basis to meet mission requirements or to avoid substantial
losses. Examples: Systems critical to safety, life support, and hurricane forecasting.

Security administrators need to decide how much time, money, and effort needs to be spent
in order to develop the appropriate security policies and controls. Each organization should

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analyze its specific needs and determine its resource and scheduling requirements and
constraints.

Computer systems, environments, and organizational policies are different, making each
computer security services and strategy unique. However, the principles of good security
remain the same, and this document focuses on those principles.

Although a security strategy can save the organization valuable time and provide important
reminders of what needs to be done, security is not a one-time activity. It is an integral
part of the system lifecycle. The activities described in this document generally require
either periodic updating or appropriate revision. These changes are made when
configurations and other conditions and circumstances change significantly or when
organizational regulations and policies require changes.

3.3 Basics of Encryption

To combat the threat from fraud and hackers even from different network attack, most
major Web sites use some form of digital encryption to protect sensitive data.

Encryption is the process of scrambling data in order to make it unreadable without special
knowledge of steps that can lead to unscrambling the code.

How Encryption is Used

With increased online use, business is conducted where the various parties have practically
no contact either face-to-face or even over the phone. Orders on a Web site can be
processed with a few clicks of the mouse. The buyer often never communicates with a
seller, except to enter a form, and the seller just simply processes orders much as it was
done in the past via mail order.

4 Establish maintenance practices

4.1 operating system and diagnostic software

Diagnostics software’s are software’s that used to make fix the computer software
problems.

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As well there are operating systems diagnostics are software that fix problems related to
operating system failure.

The following tables shows the different diagnostics tools:

No
Diagnostic Tool Type What It Does
1
POST Firmware Tests core components of system
2
pen Boot Firmware Tests system components, focusing on peripherals and
Diagnostics I/O devices
3
Open Boot Firmware Display various kinds of system information
commands
4
SC card Hardware and Monitors environmental conditions, performs basic fault
and RSC software software isolation, and provides remote console access
5
Hardware Software Exercises an operational system by running sequential
Diagnostic Suite tests. Also reports failed FRUs

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