Download Hardware Overview - La Salle University

Basic Hardware Overview
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System Case
• The major hardware components of the computer,
as opposed to the I/O devices and other
peripherals, are housed in the case.
– Also known as chassis or enclosure or system unit.
• The case helps keep the components clean and
cool.
• It can also provide some shielding to undesired
outside voltages.
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Case with
side panel
removed.
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More than just a box
• At first the case strikes one simply as a container,
but it has some structure.
• If one is building a PC, the case has to be
coordinated with the motherboard one chooses.
• The case will also determine how much access
there is to the front and back of the PC – the
number of bays, expansion slots and so on.
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• Cases come is various sizes and shapes,
known as “form factors”
– Micro tower, mini tower, mid tower, full tower,
microATX desktop, and ATX desktop.
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Power Supply
• Computers work by having a value – in binary
computers a high or low – represented by some
physical quantity.
• The physical quantity is typically an electronic
voltage or electronic current.
• Thus we need some part of the computer
responsible for supplying electronic voltages
and/or currents. This is the power supply.
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Power Supply is really a transformer
• As far as the other parts of the computer are concerned the
power does come from the power supply – except for a
few parts that have a separate battery.
• However, strictly speaking the device known as a power
supply does not supply power, it transforms it. The
source of the power is a generating station, the power is
then delivered to buildings and made available at wall
outlets. The power supplied by the outlet must be
transformed into the form that is useful for
computers.
– One could also complicate the scenario with an
Uninterruptible Power Supply (UPS) or a back-up
generator.
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AC-DC
• The outlet supplies somewhat high-voltage AC
(alternating current)
– In the US, the AC supplied is known as 110, it varies
from approximately a positive 156 volts to a negative
156 volts many times a second.
– 156 is the peak voltage, 110 is the rms (root mean
square) voltage
• Computers need low-voltage DC (direct current)
– Various components need differing amounts of steady
voltage (12 volts, 5 volts, ±3.3 volts, etc.)
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Caution
• Because of the relatively high voltages
coming in and the way in which
transformation is done, power supplies can
be dangerous.
• Do not open up a power supply, unless you
have been trained.
• Usually if a power supply goes, it is
replaced as a unit.
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Power to the
components
• The transformed power must in turn reach
the components that use it:
– The motherboard and the devices thereon
– The various drives (floppy, hard disk, CD)
– Etc.
• There is a special (larger) connector to the
mother board.
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Molex and Mini Connectors
• The drives are connected with the smaller
Molex connectors and the even smaller
Mini connectors.
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Parts of a Power Supply
Molex Connector
Mini
Connector
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Motherboard
• A circuit is a path or paths which current takes through a
set of electronic components (resistors, capacitors,
transistors, etc.).
• If a number of the components are etched into a
semiconductor, this is called a chip or integrated circuit.
• If a circuit or circuits are printed onto a board, this is called
a circuit board.
– Sometimes one inserts chips into boards.
• The main circuit board is a computer is known as the
motherboard.
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The place to meet
• The major components are on the motherboard or
plug into it.
• The motherboard has places for processor,
external cache and memory to plug into.
• These components interface with other
components via the chipset.
• The chipset leads to the controllers of various
other components (hard drive, CD, etc) and to
expansion slots so that other circuitry can be
added making the PC customizable.
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Chipset
• Most of the manipulation of data is done by the
processor. The rest is mostly moving data around.
And the main traffic cop is the chipset.
• The chipset allows the storage and input devices to
interface with the processor, memory and cache.
• The chipset will determine which processors can
be used in the PC, how much cache and memory
are allowed, etc.
• Since the chipset interfaces the components with
vastly different speeds, it can be crucial is
determining a PC’s performance.
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Controllers
• Whereas the chipset is a centralized, generic dataflow manager; controllers are individual, specific
data-flow managers that allow one to interface
with specific devices.
• Hence one has a floppy controller, a keyboard
controller, and so on.
– This has changed to a more generic USB controller
with various USB devices
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USB Controller
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Buses
• If the motherboard’s chipset and controllers are the
traffic cops, then the motherboard’s buses are the
streets.
• Since so many devices want to interface with the
processor, there is a set of shared channels for
information going to or coming from the processor.
These are the buses.
• Like streets, they can vary in speed and capacity.
There are fast buses for fast devices and slow buses
for slow devices.
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BIOS
• The Basis Input/Output System or BIOS
is firmware (instructions burned into
ROM) that interfaces between the various
hardware components on and plugged into
the motherboard and the operating system.
• This layering means that the operating
system is not dependent the specifics of the
hardware.
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BIOS
• The BIOS is written in ROM because it rarely
changes. It may be in EEPROM (Electrically
Erasable Programmable Read-Only Memory) so
that it can be changed occasionally – flashing the
BIOS.
• Being ROM also implies that these instructions
are non-volatile – not lost when the power goes
off. Thus the instructions for starting the PC are
written in this way.
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BIOS to be replaced by UEFI
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Processor
• The processor, a.k.a. the Central Processing Unit
or CPU interprets the instructions it finds in
memory (programs) and responds to and modifies
(i.e. processes) the information and directs the
other components how to respond.
• The CPU is sometimes thought of as consisting of
two parts:
– The Arithmetic Logic Unit (ALU)
– Control
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Pentium 4
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Intel® Core™ i7 Processor
Extreme Edition
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Processor
• The processor is the most important chip in a PC
– often called the brain of the computer.
• The processor has a lot of contacts called pins
which plug into the motherboard and allow
electronic information to flow to and from the
processor.
• The pins are arranged in rows around the chip’s
perimeter in what is known as the Pin Grid Array
PGA.
– There have been variations on the “pin” idea, since the
traditional notion of a pin (a long. thin piece of metal) is
easily bent.
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Processor features
• Two of the main features of processors are their
speed and their instruction set.
• Instructions are broken down into their smallest
steps and the processor speed determines the
amount of time required for one of these smallest
steps.
• A processor’s instruction set is the collection of
basic things it knows how to do.
• More recently another main feature of processors
has become the number of cores.
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Processor features
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System Memory
• The processor executes instructions. The
combination of instructions can be varied – that is,
computers can be programmed.
• The combination of instructions as well as the data
that the processor is currently acting on are held in
memory.
• Memory can be distinguished from storage by its
intimate connection to the processor and by its
volatility – data in memory, Random-Access
Memory (RAM) is lost when the power goes off.
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Cache
• There are two basic types of RAM
– Static RAM (SRAM) is fast but expensive
– Dynamic RAM (DRAM) is slow but cheap
• The processor’s speed is faster than main memory
which is made of DRAM. A special unit of faster
SRAM memory that works even more intimately
with the processor than memory is known as
cache.
• Cache is a very sophisticated game of guessing
what instructions and data the processor will next
need and placing it in the location that can be
accessed more efficiently.
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Storage
• Memory is essential (otherwise computers would
not be programmable), storage is simply a
convenience and was not a part of the earliest
computers.
• But without storage the programs and
accompanying data would have to be entered
anew each time.
• Storage is nonvolatile (keeps the information)
without needing power – so that programs and
data can be kept from execution to execution, day
to day, year to year.
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Hard disk drive
• The main storage device is the hard disk.
• The hard disk uses a magnetic material.
The magnetic property can be placed in two
states corresponding to 1’s and 0’s.
• The magnetic state can be determined
(read) or set/reset (written) by electronic
means, but the state can be maintained
without constant electric power.
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References
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•
•
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http://www.pcguide.com/
http://www.webopedia.com
http://www.whatis.com
PC Hardware in a Nutshell, Thompson and
Thompson
• A+ Certification: Exam Guide, Meyers and
Jernigan
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