This document provides an overview of key computer hardware components and concepts. It begins with explanations of computer architecture including Von Neumann architecture and differences between RISC and CISC instruction sets. It then covers the central processing unit (CPU) and its components. Other sections describe the motherboard, types of memory including RAM, ROM, and cache memory. Additional topics include storage devices like hard disk drives and solid state drives, as well as concepts such as multitasking, multiprocessing, and multithreading.

1. 1
Principles
of
Computer
Design

2. 2
Contents
Computer Architecture........................ 5
Von Neumann Architecture .......... 5
Intel CPU Microarchitectures............... 9
RISC and CISC Instruction Set............. 10
RISC.............................................. 10
Typical RISC Architecture Based
Machine – Instruction Phase
Overlapping................................. 12
Advanced RISC Machine.............. 13
CISC.............................................. 14
Typical CISC Architecture – Stack
Design.......................................... 15
RISC and CISC in Comparison ...... 16
CPU Benchmark ................................. 17
CPU .................................................... 19
Components of the CPU.............. 21
Motherboard ..................................... 24

3. 3
ASUS P5AD2-E Premium
Motherboard............................... 26
RAM ................................................... 29
VGA........Error! Bookmark not defined.
ROM................................................... 34
HDD.................................................... 36
Hard disk drive components ....... 37
SSD............................................... 39
MULTITASKING .................................. 40
Advantages of multitasking......... 41
Disadvantages of multitasking .... 41
MULTIPROCESSING............................ 42
MULTITHREADING ............................. 44
CPU Core Structure............................ 47
Single Core................................... 47
Dual-core..................................... 48
Multi-core.................................... 50

4. 4
Nanotechnology CPU Design ............. 51
Cache Memory................................... 53
L1 and L2 Caches......................... 54
Smart Caching ............................. 55
BIOS.................................................... 56
The four main functions of a PC
BIOS............................................. 57
Windows Registry.............................. 60
Registry Root Keys (hive name)... 62
Windows Registry values ............ 64
Protect Computer from Threat.......... 66
Ergonomic rules................................. 69
Computer Ergonomics - Working
Positions...................................... 70
Computer Ergonomics - Placement
of Components............................ 71

5. 5
Computer Architecture
Von Neumann Architecture
It is the first written description of how an
electronic computer should store and
processes information.
Von Neumann architecture was originally
published in John von Neumann's report of the
EDVAC on June 30, 1945.

6. 6
This architecture is consist of:
 an Arithmetic Logic Unit (ALU)
 memory
 Input/output
 a control unit

7. 7
Von Neumann computers have some
drawbacks.
 They carry out instructions one after
another, in a single linear sequence
 They spend a lot of time moving data
to and from the memory.
This slows the computer and as an instruction
fetch and a data operation cannot occur at the
same time because they share a common bus;
this problem is called as the von Neumann
bottleneck.
One way to avoid the von Neumann
bottleneck is to build the computer so it
performs operations in parallel (so-called
parallel processing).
Another common trick is to separate the bus
into two or more busses, one for instructions,
another for data.

8. 8
But such modifications don't really amount to
much more than variations of the original
architecture.
This design is still used, in one form or
another, in all computers and many electronic
devices produced today.

9. 9
Intel CPU Microarchitectures

10. 10
RISC and CISC Instruction Set
RISC
Reduced Instruction Set Computer (RISC)
is a type of microprocessor architecture that
utilizes a small, highly-optimized set of
instructions.
The first RISC projects came from IBM,
Stanford, and UC-Berkeley in the late 70s
and early 80s.
The IBM 801, Stanford 3 [RISC AND CISC]
MIPS, and Berkeley RISC 1 and 2 were all
designed with a similar philosophy which has
become known as RISC.

11. 11
Some design feature characteristics of RISC
processors:
 One cycle execution time: RISC
processors have a CPI (clock per instruction)
of one cycle. This is due to the optimization of
each instruction on the CPU and a technique
called;
 Pipelining: a technique that allows for
simultaneous execution of parts, or stages, of
instructions to more efficiently process
instructions;
 Large number of registers: the RISC
design philosophy generally incorporates a
larger number of registers to prevent in large
amounts of interactions with memory

12. 12
Typical RISC Architecture Based Machine –
Instruction Phase Overlapping

13. 13
Advanced RISC Machine

14. 14
CISC
Complex Instruction Set Computer or
Computing is a type of microprocessor design
which refers to computers designed with a full
set of computer instructions that were intended
to provide needed capabilities in the most
efficient way.
CISC architecture contains a large set of
computer instructions that range from very
simple to very complex and specialized but by
reducing the full set to only the most frequently
used instructions, the computer would get more
work done in a shorter amount of time for most
applications (RISC).
Examples of CISC Processors are:
 Motorola 680x0 family
 Intel 80186 through Intel 486 &
Pentium.

15. 15
Typical CISC Architecture – Stack Design

16. 16
RISC and CISC in Comparison

17. 17
CPU Benchmark
CPU benchmarking is a type of measurement
for computer performance. It is applied to the
central processing unit, or CPU, of the
computer system.
These measurements help observers to
understand standards for computer
functionality. Moreover, they provide a set of
standards that allow users to compare the
performance of different machines under the
same circumstances.
CPU benchmarking increases speed and
capacity or capability.
The observers will often assess the clock rate,
which is the rate that the CPU can process
commands. Other types of processor function
may also be assessed. The benchmark will
provide the core standard for the design of a
CPU, or simply be recorded in quality or

18. 18
production research. The final outcome
involves much more testing and trials of
developed prototypes.
The software that helps to determine
benchmarks must be matched with specific
operating systems.

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CPU
CPU is the Central Processing Unit of the
computer which also known as a processor,
central processor, or microprocessor.
It handles all instructions it receives
from hardware and software running on the
computer.
The CPU was first developed at Intel with the
help of Ted Hoff and others in the early 1970's.

20. 20
The first processor released by Intel was
the4004 processor.
The processor is placed and secured into a
compatible CPU socket found on the
motherboard. Processors produce heat, so
they are covered with a heat sink to keep them
cool and running smoothly.
The CPU chip is usually in the shape of a
square or rectangle and has one notched corner
to help place the chip properly into the CPU
socket. On the bottom of the chip are hundreds
of connector pins that plug into each of the
corresponding holes in the socket.

21. 21
Components of the CPU
The primary components of the CPU are:
 ALU (Arithmetic Logic Unit) -
performs mathematical, logical, and
decision operations
 CU (Control Unit) - directs all of the
processors operations

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There are several types of processors. The
AMD Opteron series and Intel Itanium
and Xeon series are CPUs used in servers and
high-end workstation computers.
Some mobile devices, like smartphones and
tablets, use ARM CPUs. These CPUs are
smaller in size, require less power, and generate
less heat.
AMD Processors:
 K6-2
 K6-III
 Athlon
 Duron
 Athlon XP
 Sempron
 Athlon 64
 Mobile Athlon 64
 Athlon XP-M
 Athlon 64 FX
 Turion 64
 Athlon 64 X2
 Turion 64 X2
 Phenom FX
 Phenom X4
 Phenom X3
 Athlon 6-series
 Athlon 4-series
 Athlon X2
 Phenom II
 Athlon II
 E2 series

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 A4 series
 A6 series
 A8 series
 A10 series
Intel Processors:
 4004
 8080
 8086
 8087
 8088
 80286 (286)
 80386 (386)
 80486 (486)
 Pentium
 Pentium w/MMX
 Pentium Pro
 Pentium II
 Celeron
 Pentium III
 Pentium M
 Celeron M
 Pentium 4
 Mobile Pentium
4-M
 Pentium D
 Pentium Extreme
Edition
 Core Duo
 Core 2 Duo
 Core i3
 Core i5
 Core i7

24. 24
Motherboard
Alternatively referred to as the mb, mainboard,
mobo, mobd, backplane board, base board,
main circuit board, planar board, system board,
or a logic board on Apple computers.
The first motherboard is considered to be one
used in the IBM Personal Computer, released
in 1981. At the time, IBM referred to it as a
"planar" instead of a motherboard.
The motherboard is a printed circuit board that
is the foundation of a computer, located on the
back side or at the bottom of the computer case.
It allocates power to the CPU, RAM, and all
other computer hardware components.
Most importantly, the motherboard allows
hardware components to communicate with
one another.

25. 25
The computer components included in the
motherboard are:
 The microprocessor
 (Optionally) coprocessors
 Memory
 basic input/output system (BIOS)
 Expansion slot
 Interconnecting circuitry
Additional components can be added to a
motherboard through its expansion slot.
The electronic interface between the
motherboard and the smaller boards or cards in
the expansion slots is called the bus.

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ASUS P5AD2-E Premium Motherboard

27. 27
There are several motherboard brands in the
world.
 Gigabyte
Gigabyte may very well
be the best motherboard
brand out there.
Gigabyte motherboards have received
consistent, above average to high ratings from
all major computer supply sites.
 EVGA
EVGA is a computer
parts manufacturer that
focuses mainly on
motherboards and graphics cards. Like Asus
and Gigabyte, EVGA is another company that
has received some great reviews from
consumers.

28. 28
 Intel
Intel has the least variety for
motherboards, and selection is
limited. However, their
motherboards are top quality,
and receive positive reviews from customers
the majority of the time.
 Asus
Asus currently distribute
motherboards, graphics
cards, computer monitors and even their own
brand of PCs. Unlike other PC manufacturers
like Dell, HP, and Gateway, Asus sells their
motherboards on sites like Newegg and Tiger
Direct, so that computer builders and
gamers can purchase just the motherboard at an
affordable price.

29. 29
RAM
Random Access Memory, a type of computer
memory that can be accessed randomly; that is,
any byte of memory can be accessed without
touching the preceding bytes. RAM is the most
common type of memory found in computers
and other devices, such as printers.

30. 30
There are two main types of RAM.
 DRAM (Dynamic Random Access
Memory)
 SRAM (Static Random Access
Memory).
The two types of RAM differ in the technology
they use to hold data, with DRAM being the
more common type. In terms of speed, SRAM
is faster. DRAM needs to be refreshed
thousands of times per second while SRAM
does not need to be refreshed, which is what
makes it faster than DRAM.
DRAM supports access times of about 60
nanoseconds, SRAM can give access times as
low as 10 nanoseconds. Despite SRAM being
faster, it's not as commonly used as DRAM
because it's more expensive. Both types of
RAM are volatile, meaning that they lose their
contents when the power is turned off.
DDRx

31. 31
DDRx SDRAM is a family of random access
memory that provides high bandwidth storage
of data for electronic devices.
There have been a number of DDR evolutions
starting with DDR then DDR2 and now DDR3.
Each new version is an improvement on its
forerunner with DDR3 being able to process
data at twice the rate of DDR2.
The physical layout for the DDR interface is
specified by the silicon vendors and published
in their layout guidelines and this has evolved
with each adaptation of the memory interface.

32. 32
VGA
Video Graphics Array, a graphics display
system for PCs developed by IBM.VGA has
become one of the de facto standards for PCs.
In text mode, VGA systems provide
a resolution of 720 by 400 pixels. In graphics
mode, the resolution is either 640 by 480 (with
16 colours) or 320 by 200 (with 256 colours).
The total palette of colours is 262,144.
Unlike earlier graphics standards for PCs -
- MDA, CGA, and EGA – VGA uses analog
signals rather than digital signals.
Consequently, a monitor designed for one of
the older standards will not be able to use VGA.
Since its introduction in 1987, several other
standards have been developed that offer
greater resolution and more colours, but VGA
remains the lowest common denominator.

33. 33
All PCs made today support VGA, and
possibly some other more advanced standard.

34. 34
ROM
Read – Only Memory is a computer memory
on which data has been pre-recorded. Once
data has been written onto a ROM chip, it
cannot be removed and can only be read.
Unlike main memory (RAM), ROM retains its
contents even when the computer is turned off.
ROM is referred to as being non-volatile,
whereas RAM is volatile.

35. 35
Most personal computers contain a small
amount of ROM that stores critical programs
such as the program that boots the computer. In
addition, ROMs are used highly in calculators
and peripheral devices such as laser printers,
whose fonts are often stored in ROMs.
PROM or Programmable Read - Only
Memory is another variation of ROM. PROMs
are manufactured as blank chips on which data
can be written with a special device called a
PROM programmer.

36. 36
HDD
A computer Hard Disk Drive is the mechanism
that controls the positioning, reading and
writing of the hard disk, which furnishes
data storage.
A hard disk drive / hard drive / hard disk are
not the same thing, but they are packaged as a
unit and either term can refer to the whole unit.
Hard disk drives can be found in desktop
computers, mobile devices, consumer
electronics and enterprise storage arrays in data
centers.

37. 37
Hard disk drive components

38. 38
Most basic hard drives consist of a number of
disk platters that are positioned around a
spindle inside a sealed chamber. The chamber
also includes read-and-write heads and motors.
The motor is used to spin the platters, which
hold the data, at up to 15,000 rotations per
minute. A higher rpm number results in faster
performance.
As the platters spin, a second motor controls the
position of the read-and-write heads that record
information to, and read information from,
tracks on each platter

39. 39
SSD
The main alternative to hard disk drives in PCs
and the enterprise are Solid - State Drives
(SSDs). Unlike hard disks, SSDs contain no
moving parts.
SSDs also have a lower latency than HDDs,
and are therefore often favoured to store critical
data that needs to be accessed quickly and for
applications with a high input demand.
They are more expensive than HDDs from a
price-per-gigabyte standpoint. Many enterprise
storage arrays ship with a mix of HDDs and
SSDs to reduce costs while providing better
performance.

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MULTITASKING
Multitasking, in an operating system. It allows
a user to perform more than one computer
task (such as the operation of an application
program) at a time.
The operating system is able to keep track of
where you are in these tasks and go from one to
the other without losing information.
Microsoft Windows 2000, IBM's OS/390, and
Linux are examples of operating systems that
can do multitasking.
As an example, when you open your
Web browser and then open Word at the same
time, you are causing the operating system to
do multitasking.
Being able to do multitasking doesn't mean that
an unlimited number of tasks can be juggled at
the same time. Each task consumes system

41. 41
storage and other resources. As more tasks are
started, the system may slow down or begin to
run out of shared storage.
Advantages of multitasking
 Data can be copied and moved between
programs.
 More productive, since dozens of
different program can be running at
once.
 Programs that are updated can be seen
immediately. For example, if a new e-
mail is received you immediately
known.
Disadvantages of multitasking
 Requires more system resources.
 If on a laptop or portable device takes
more battery power.

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MULTIPROCESSING
Multiprocessing is the coordinated processing
of programs by more than one computer
processor.
Multiprocessing is a general term that can
mean the dynamic assignment of a program to
one of two or more computers working in
tandem or can involve multiple computers
working on the same program at the same time
(in parallel).
With the advent of parallel processing,
multiprocessing is divided into Symmetric
Multiprocessing (SMP) and Massively
Parallel Processing (MPP).
In symmetric (or "tightly coupled")
multiprocessing, the processors share memory
and the I/O bus or data path.

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A single copy of the operating system is in
charge of all the processors. SMP, also known
as a "shared everything" system, does not
usually exceed 16 processors.
In massively parallel (or "loosely coupled")
processing, up to 200 or more processors can
work on the same application.
Each processor has its own operating system
and memory, but an "interconnect"
arrangement of data paths allows messages to
be sent between processors.
Typically, the setup for MPP is more
complicated, requiring thought about how to
partition a common database among processors
and how to assign work among the processors.
An MPP system is also known as a "shared
nothing" system.

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MULTITHREADING
Multithreading is a type of execution model
that allows multiple threads to exist within the
context of a process such that they execute
independently but share their process
resources.
A thread maintains a list of information
relevant to its execution including;
 The priority schedule,
 Exception handlers,
 A set of CPU registers,
 Stack state in the address space of its
hosting process.
Threading can be useful in a single-processor
system by allowing the main execution thread
to be responsive to user input, while the
additional worker thread can execute long-
running tasks that do not need user intervention
in the background.

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Threading in a multiprocessor system results in
true concurrent execution of threads across
multiple processors and is therefore faster.
However, it requires more careful
programming to avoid non-intuitive behaviour
such as racing conditions, deadlocks, etc.
Operating systems use threading in two ways:
 Pre-emptive multithreading –
The context switch is controlled by the
operating system. Context switching
might be performed at an inappropriate
time, hence, a high priority thread could
be indirectly pre-empted by a low
priority thread.
 Cooperative multithreading –
The context switching is controlled by
the thread. This could lead to problems,
such as deadlocks, if a thread is blocked
waiting for a resource to become free.

46. 46
The 32- and 64-bit versions of Windows use
pre-emptive multithreading in which the
available processor time is shared such that all
the threads get an equal time slice and are
serviced in a queue-based mode.
During thread switching, the context of a pre-
empted thread is stored and reloaded in the next
thread in the queue. The time slice is so short
that the running threads seem to be executing
in parallel.

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CPU Core Structure
A processor core is a processing unit which
reads in instructions to perform specific
actions. Instructions are chained together so
that, when run in real time, they make up your
computer experience.
As the name suggests, single, dual, quad and
octa have 1, 2, 4, and 8 cores respectively.
Multi core processors are designed to perform
multi-tasking and parallel processing
simultaneously.
Single Core
A single core processor completes the entire
instruction cycle of all the instructions,
consisting of fetch, decode, execute, memory
access and write back within a single core.

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Dual-core
Dual-core refers to a processing unit that
includes two complete execution cores per
physical processor. It has combined two
processors and their caches and cache
controllers onto a single IC.

49. 49
Dual-core processors are well-suited for
multitasking environments because there are
two complete execution cores instead of one,
each with an independent interface to the front-
side bus.
Since each core has its own cache, the
operating system has sufficient resources to
handle most compute intensive tasks in
parallel. Hence the instructions can now be
executed by either of the cores, which is free to
handle them.

50. 50
Multi-core
Multi-core is similar to dual-core in that it is an
expansion to the dual-core technology which
allows for more than two separate processors.
This hold true for quad and octa core
processors.
From the point of view of multi-tasking, 1.2
GHz quad core is definitely better, even if the
clock speed is slightly less.

51. 51
Nanotechnology CPU Design
Nanotechnology in computers provides the
need for faster running computer processes at
cooler temperatures than traditional, transistor-
based computer components.
In traditional computing, transistors have used
silicon components as an affordable and easily
manufactured method to provide smaller and
faster computers and electronic gadgets, such
as netbooks, smartphones and personal
assistant devices. Such powerful gadgets at so
small a size produce too much heat, however,
reducing the effectiveness, performance and
longevity of the silicon components.
Nanotechnology in computing solves the heat
dilemma by providing improved processor
power at cooler temperatures and lighter
weights.

52. 52
Nanotechnology in computers makes use of
nanomaterials, tiny molecule-sized machines
that process information similarly to the
intricate and complex cells in a living
organism.
Similar to cells, nanomaterials exist on a
microscopic level, one nanometer measuring
one billionth of a meter, or 1/50,000 the
thickness of a human hair. Nanotechnology in
computing therefore operates on a minuscule
level.
Computer manufacturers create long,
microscopic strands of carbon atoms,
called carbon nanotubes, into tiny transistors
that provide twice the processing power of
silicon chips, while generating much less heat
and lighter components.
Nanotechnology applications offer more
efficient performance, which conserve power
and increase battery life for smaller, portable
electronic devices.

53. 53
Cache Memory
Cache memory is a small-sized type of volatile
computer memory that provides high-speed
data access to a processor and stores frequently
used computer programs, applications and
data.
A memory cache is a portion of memory made
of high-speed static RAM (SRAM). Memory
caching is effective because most programs
access the same data or instructions over and
over. By keeping as much of this information
as possible in SRAM, the computer avoids
accessing the slower DRAM.

54. 54
L1 and L2 Caches
Some memory caches are built into
the architecture of microprocessors. The Intel
80486 microprocessor contains an 8K memory
cache, and the Pentium has a 16K cache.
Such internal caches are often called Level 1
(L1) caches.
Most modern PCs also come with external
cache memory, called Level 2 (L2) caches.
These caches sit between the CPU and the
DRAM. Like L1 caches, L2 caches are
composed of SRAM but they are much larger.
Disk Caching
Disk caching works under the same principle as
memory caching. A disk cache uses
conventional main memory. The most recently
accessed data from the disk is stored in a
memory buffer.

55. 55
When a program needs to access data from the
disk, it first checks the disk cache to see if the
data is there. Disk caching can dramatically
improve the performance of applications,
because accessing a byte of data in RAM can
be thousands of times faster than accessing a
byte on a hard disk.
Smart Caching
When data is found in the cache, it is called
a cache hit, and the effectiveness of a cache is
judged by its hit rate.
Many cache systems use a technique known
as smart caching, in which the system can
recognize certain types of frequently used data.
The strategies for determining which
information should be kept in the cache
constitute some of the more interesting
problems in computer science.

56. 56
BIOS
The Basic Input/Output System is a ROM chip
located on all motherboards that allows you to
access and set up your computer system at the
most basic level. Examples of BIOS
manufactures are AMI, Phoenix etc.
The BIOS includes instructions on how to load
basic computer hardware and includes a test
referred to as a POST (Power On Self Test)
that helps verify the computer meets
requirements to boot up properly.

57. 57
If the computer does not pass the POST, you
will receive a combination of beeps indicating
what is malfunctioning within the computer.
The four main functions of a PC BIOS
 POST
Test the computer hardware and make sure no
errors exist before loading the operating
system.
 Bootstrap Loader
Locate a capable operating system, and the
BIOS will pass control to it.
 BIOS drivers
Low level drivers that give the computer basic
operational control over your computer's
hardware.
 BIOS or CMOS Setup
Configuration program that allows you to
configure hardware settings including system

58. 58
settings such as computer passwords, time, and
date.
BIOS is a program that is made accessible to
the microprocessor on an erasable
programmable read-only memory (EPROM)
chip.
When you turn on your computer, the
microprocessor passes control to the BIOS
program, which is always located at the same
place on EPROM.
When BIOS boots up your computer, it first
determines whether all of the attachments are
in place and operational and then it loads the
operating system into your computer's RAM
from your hard disk or diskette drive.
With BIOS, your operating system and its
applications are freed from having to
understand exact details about the attached
input/output devices. When device details
change, only the BIOS program needs to be

59. 59
changed. Sometimes this change can be made
during your system setup.
Although BIOS is theoretically always the
intermediary between the microprocessor and
I/O device control information and data flow,
in some cases, BIOS can arrange for data to
flow directly to memory from devices that
require faster data flow to be effective.

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Windows Registry
Windows Registry contains information,
settings, options, and other values for programs
and hardware installed on all versions of
Microsoft Windows operating systems.
For example, when a program is installed, a
new sub key containing settings like a
program's location, its version, and how to start
the program, are all added to the Windows
Registry.
When Windows was initially released, it relied
heavily on .ini files to store Windows and
Windows programs configurations and
settings. Although .ini files are still sometimes
used, most Windows programs rely on settings
made to the Windows Registry after being
installed.
To view and make changes to the Windows
Registry, the Windows Registry Editor may be

61. 61
used. In Windows 3.x, the Registry Editor was
known as the Registration Info Editor or
Registration Editor.
The Registry Editor allows you to view all keys
and values that are in the Registry as well as
change Windows, program, or driver values
you feel are necessary.

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Registry Root Keys (hive name)
When first opening the Windows Registry
Editor, it displays root keys that contain all
Registry values. The most common root keys
and the values:
 HKEY_CLASSES_ROOT (HKCR)
Describes file type, file extension, and OLE
information.
 HKEY_CURRENT_USER (HKCU)
Contains user who is currently logged into
Windows and their settings.
 HKEY_LOCAL_MACHINE (HKLM)
Contains computer-specific information about
the hardware installed, software settings, and
other information. This information is used for
all users who log on to this computer and is one
of the more commonly accessed areas in the
Registry.

63. 63
 HKEY_USERS (HKU)
Contains information about all the users who
log on to the computer, including both generic
and user-specific information.
 HKEY_CURRENT_CONFIG
(HKCC)
The details about the current configuration of
hardware attached to the computer.
 HKEY_DYN_DATA (HKDD)
Only used in Windows 95, 98, and NT this key
contained the dynamic status information and
Plug-and-Play information. This information
may change as devices are added to or removed
from the computer. The information for each
device includes the related hardware key and
the device's current status, including problems.

64. 64
Windows Registry values
 Closed key
Like the folders seen in Windows Explorer
which contain the Registry sub keys.
 Open key
When a key is opened the icon changes to an
expanded or open key and displays all its
contents and any additional sub keys.
 String value
REG_SZ type. Allows for any string value to
be defined on a single line, such as a file path.
 String array value
REG_MULTI_SZ type. Any multi-line
string value.
 Expanded string value
REG_EXPAND_SZ type. Contains a string
with variables that need to be expanded. For

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example, c:%windir%example.exe could be
the same as C:windowsexample.exe.
 Binary value
REG_BINARY type. Allows for attributes to
be defined in binary as either on or off (0 or
1).
 DWORD value
REG_DWORD type. Similar to the binary
value, but capable of values being defined in
either 32-bit decimal or hex.
 QWORD value
REG_QWORD type. Like the DWORD, but
stored as a 64-bit value.

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Protect Computer from Threat
 Don’t be insecure.
The first step toward protecting your computer
is simply making sure it’s equipped with
antivirus software.
 Keep current.
If you have antivirus software but don’t always
make sure it’s always updated, you may as well
just offer your computer’s sensitive data up to
hackers. With new strains of malware being
produced every day, security software must be
updated just as often to best protect your
computer.
 Click with caution.
Never click on unknown email attachments,
shady ads or other suspicious links, and
keeping your web browser and its plugins
(like Adobe’s Flash) up to date.

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 Bring backup.
If you’re not regularly backing up your
computer files, you risk losing them all in a
malware attack.
 Surf with protection.
When you use a wireless connection, your data
is literally floating around in the air, and
anyone who knows how, can eavesdrop on
your computer. Free Wi-Fi is an unsafe public
network. The easiest way to protect yourself is
to connect only to secure networks: They
usually have a lock symbol next to them and
may mention “WPA” or “WEP encryption.
These networks garble up the data you’re
transmitting so it won’t make sense to anyone
trying to steal it.
 Think complicated.
Some people use the same password for
everything; others make them too simple. Try
to get a mix of letters and non-consecutive
numbers for the best protection. And avoid

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having one universal log-in, so that if one
password gets hacked, you don’t risk
everything.
 Install a firewall
A firewall enacts the role of a security guard.
There are of two types of firewalls: a software
firewall and hardware firewall. Each serves
similar, but different purposes. A firewall is the
first step to provide security to the computer. It
creates a barrier between the computer and any
unauthorized program trying to come in
through the Internet. If you are using a system
at home, turn on the firewall permanently. It
makes you aware if there are any unauthorized
efforts to use your system.

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Ergonomic rules
These are the rules designed to provide
optimum comfort and to avoid stress or injury.
Ergonomics related to computers seek to
alleviate stress conditions by focusing on a
number of different things, including:
 Wrist support for the keyboard
 Key board angle
 Chair height and type
 Back support
 Lighting in the room
 Placement of documents, phones, and
other frequently used items
Each of these things, and more, have a direct
effect on your comfort and the overall stress to
your eyes, joints, wrists, and other body parts
as you spend prolonged periods of time in front
of the computer.

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Computer ergonomics deals with the
placement and set up of desks, computers and
computer equipment, and lighting so that it
minimizes stresses and risks.
Computer Ergonomics - Working Positions
If you are working at a computer, the way you
sit and align your body will affect you. The
ideal situation and set up would include:
 The top of the monitor should be
situated at or below eye level.
 Head and neck are balanced and in line
with the torso, so you are sitting up
straight in your chair and not hunched
over the keyboard.
 The elbows are supported and close to
the body, with the wrists and hands in
line with the forearms.
 Lower back should be supported in an
ergonomic chair or with a pillow.

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Stools should be avoided when sitting
at a computer.
 The feet should be flat on the floor.
Computer Ergonomics - Placement of
Components
Where the components of your desk and
computer are placed is also important to your
overall health.
 Computer monitor. Ideally, your
monitor should be situated so you don’t
have to strain your neck and lean
forward to look at it. You don’t want to
have it too close or too far from you, as
this can result in blurred vision. In
addition, it should be placed in an area
where there is sufficient lighting and
reduced glare.
 Key board: The placement and support
of the keyboard are also important, as

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continual typing puts you at increased
risk for carpal tunnel syndrome. Your
keyboard should be placed so that your
arms are parallel with the floor.
 Computer mouse: The mouse should be
placed so that it allows for a straight,
neutral wrist position. You can use a
mouse pad with a special wrist support
so you can keep this neutral position.
 Desk: Your desk should have sufficient
space for your computer, mouse, phone,
documents, and anything else so you
are not cramped or overcrowded. The
desk should also be made so a chair can
fit comfortably under it, and your knees
are not hitting drawers or supportive
structures for the desk.
 Chair: Your chair should allow you to
be level with the computer screen while

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at the same time providing sufficient
support for your back.
Computer ergonomics allow you to work with
a computer more comfortably. The above rules
will help you to follow computer ergonomic
guidelines so you will have the least amount of
stress on your eyes and joints as possible.