Unit 2: Computer Systems Session One Part One 1

Unit 2: Computer Systems
Session One Part One
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Aims:
Discussion into what will be covered in this unit.
Assessment
Understand the basic principles
Gain an understanding into the system components
Power supply
Motherboard
Chipsets
Processor
Cache Memory
(Continued on Part 2)
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What is covered?
Computer components
Internal system unit components
Peripherals
Backing storage
Operating system software
Software utilities
Recommend computer systems
Organisational requirements
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What is covered?
Set up and maintain computer systems
Install hardware and software
PC Configuration
Testing
Maintenance
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How will you be assessed?
Two Assignments
Practical observations within a system support lab
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Basic Principles
Input device
• keyboard
• mouse
• microphone
CPU
Central Processing Unit
Output device
• screen
• printer
• speaker
Can you name any other input and output devices?
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Basic Principles
Input devices
Input device
CPU
Central Processing Unit
Output device
Input devices
 Capture information from the real world
 Send data to the CPU
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Basic Principles
Output devices
Input device
CPU
Central Processing Unit
Output device
Output devices
Are sent data by the CPU
Convert the data to an understandable form, e.g.
images on screen, sounds, printed text
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Basic Principles
Where is data stored
• Hard disk • CD
• USB device • DVD
Backing store
Input device
CPU
Central Processing Unit
Output device
Main memory
• RAM
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Basic Principles
How is data stored
All computer data is stored as binary patterns.
Binary patterns are combinations of 1s and 0s,
e.g. 10001001001110
Each 1 or 0 is known as a bit.
Binary patterns are usually stored in groups of
8, 16, 24, 32 or 64 bits.
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Basic Principles
What is data
Data is unorganised facts, numbers, letters and
symbols represented in a formalised manner
suitable for communication, interpretation and
processing by computers. (Binary code)
What is information?
Information is data which has been assigned a
commonly understood meaning. (Human
understanding)
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System components

Power

Motherboard

Chipsets

The Processor

System Memory

Video Cards

System Case

Monitors

Hard Disk Drives

CD-ROM Drives
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Power
The power supply converts the alternating
current (AC) line from your home to the
direct current (DC) needed by the
personal computer.
Power supplies, often referred to as
"switching power supplies", use switcher
technology to convert the AC input to
lower DC voltages. The typical voltages
supplied are:
 3.3 volts
 5 volts
 12 volts
The 3.3- and 5-volts are typically used by
digital circuits, while the 12-volt is used to
run motors in disk drives and fans. The
main specification of a power supply is in
watts. A watt is the product of the
voltage in volts and the current in amps
http://computer.howstuffworks.com/power-supply.htm
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Motherboard
This is the main circuit board that all
of the other internal components
connect to.
The CPU and memory are usually on
the motherboard. Other systems may
be found directly on the motherboard
or connected to it through a
secondary connection.
For example, a sound card can be
built into the motherboard or
connected through PCI (Peripheral
Component Interface) or a graphics
card connected via the AGP
(Accelerated Graphics Port)
http://www.tech-faq.com/motherboard.html
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Motherboard Continued
The most important thing to
remember about the motherboard is
that it is a printed circuit board which
provides all the connections,
pathways and "lines" connecting the
different components of the computer
to each other - specifically, the
Central Processing Unit or CPU,
which is where (as its name implies)
all the "processing" is going on to
everything else.
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Chipsets
A set of chips that provides the
interfaces between all of the PC's
subsystems. It provides the buses
and electronics to allow the CPU,
memory and input/output devices to
interact.
The most important connections are
to the chipsets - especially the
Northbridge chipset which is
connected to the main computer
memory (RAM, AGP), while the
Southbridge set is connected to the
peripherals -IDE controllers, BIOS
etc.
http://en.wikipedia.org/wiki/Chipset
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Processor
A CPU - also known as a microprocessor - is a
complete computation engine that is fabricated
on a single chip. Often referred to as the brain
of the computer.
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Processor Continued
Controls the transmission of data from input
devices to memory
Processes the data held in main memory
Controls the transmission of information from main
memory to output devices
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Processor Continued
The CPU uses its ALU (Arithmetic Logic Unit) to enable it to perform
mathematical operations like addition, subtraction, multiplication and
division.
Modern CPUs contain complete floating point processors that can perform
extremely sophisticated operations on large floating point numbers.
A CPU can move data from one memory location to another.
A CPU can make decisions and jump to a new set of instructions based on
those decisions.
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Processor Continued
CPU – fetch-decode execute cycle
The fundamental operation of most CPUs, regardless of the physical
form they take, is to execute a sequence of stored instructions called a
program. This is achieved by using the fetch-decode and execute
cycle.
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Processor Continued
Fetch
Fetch involves retrieving an instruction from program memory.
The location in program memory is determined by a program
counter (PC), the program counter keeps track of the CPU's place
in the current program. Often the instruction to be fetched must be
retrieved from relatively slow memory, causing the CPU to stall
while waiting for the instruction to be returned. This issue is largely
addressed in modern processors by caches.
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Processor Continued
Decode
The instruction that the CPU fetches from memory is used to
determine what the CPU is to do. In the decode step, the
instruction is broken up into parts that have significance to other
portions of the CPU.
The way in which the numerical instruction value is interpreted is
defined by the CPU's instruction set architecture (ISA).
Often, one group of numbers in the instruction, called the opcode,
indicates which operation to perform. The remaining parts of the
number usually provide information required for that instruction,
such as operands for an addition operation.
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Processor Continued
Execute
During this step, various portions of the CPU are connected so
they can perform the desired operation. If, for instance, an addition
operation was requested, an arithmetic logic unit (ALU) will be
connected to a set of inputs and a set of outputs. The inputs
provide the numbers to be added, and the outputs will contain the
final sum.
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Types of CPU
 Intel and Advanced Micro Devices (AMD) lead
the market in terms of speed and quality.
 Intel's desktop CPUs include Celeron, Pentium,
and Core.
 AMD's desktop processors include Sempron,
Athlon, and Phenom.
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Cache Memory
 CPU – Cache Memory
 high-speed memory used as a temporary store for recently processed
instructions and data, or those which the CPU predicts will be
processed soon
 Much quicker to access instructions and data from cache memory than
requesting it from normal RAM
Two types of cache exist, Level 2 (L2) and Level 1 (L1)
 L2 cache can be on the motherboard, located between the CPU and
RAM
 L1 cache is part of the CPU itself.
Cache memory is typically very expensive, so would be prohibitive in great
quantities.
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Types of CPU continued
 Getting a processor with a dual, triple, or quad core can
make a significant difference in the processing power of
your computer.
 It's like having two, three, or four separate processors
installed on your computer at one time.
 These processors work together to make your computer
multitask faster and with greater efficiency. Getting a
CPU with a larger front side bus can enhance the
processor's ability to communicate with RAM, which will
increase your computer's overall speed.
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Conclusion:
Discussed what will be covered in this unit
Outlined the Assessment strategy
Demonstrated some Understanding into the basic principles
Gained an understanding into the system components
Power supply
Motherboard
Chipsets
Processor
Cache Memory
(Continued on Part 2)
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