INSIDE THE COMPUTER:

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INSIDE THE COMPUTER CENTRAL PROCESSING
UNIT (CPU) AND INPUT/OUTPUT
DEVICES
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EXPANSION BOARDS adding capabilities
Graphics adapter permit interfacing with
video monitors (VGA video graphics array and
AGP accelerated graphics
port enable interfacing of
high-resolution monitors with the
processor) Sound card enables sound to be
captured and stored on disk and enables
sound to be played through external
speakers Data/voice/fax modem permits
communication with remote computers via a
telephone-line link. On top of the functions
of a regular modem, this one also enables
you to make phone calls, and allows your PC
to mimic a fax machine.
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IDE cable
Data buses
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A fleet of buses
ISA bus the oldest and the slowest is being
phased out of modern PCs PCI local bus
enables expansion boards to be linked
directly to the systems common bus SCSI bus
alternative to the expansion bus up to 15
devices can be linked along a single cable
(daisy chained), internal and external, with
multiple SCSI connectors USB (universal
serial bus) permits up to 127 peripheral
devices to be connected to a single USB
port. Eliminates the hassle of installing
expansion cards.
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The Motherboard
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Serial versus Parallel Ports
Serial port allows the serial transmission of
data, one bit at a time eg. An external
modem Parallel port allows the parallel
transmission of data ie several bits
simultaneously eg printers, external magnetic
disk units, and other computers SCSI port
provides parallel interface to the SCSI bus
that enables faster data transmission than
serial and parallel ports
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Intel 80826 microprocessor
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von Neumann Architecture
A memory containing both data and instructions.
Also to allow both data and instruction memory
locations to be read from, and written to, in any
desired order.
A calculating unit capable of performing both
arithmetic and logical operations on the data.
A control unit, which could interpret an
instruction retrieved from the memory and select
alternative courses of action based on the
results of previous operations.
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The microprocessor can be referred to as the
brain of the PC. The microprocessor is also
known as the CPU (Central Processing Unit).
The microprocessor does the following 1-
Carries out commands to make the hardware
components perform actions. 2- Processes data.
This involves - Performing logical
instructions such as comparing - Performing
mathematical instructions such as adding and
subtracting
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CPU
The CPU is the computers brain. This device
does all of the processing within the computer.
CPU stands for Central Processing Unit. CPU
speeds are calculated in terms of megahertz, this
is known as the system clock speed.   What is a
hertz? A hertz is a unit of measurement based on
one second. It is what is known as a frequency
measurement. A frequency is something that
cycles from one point to another point.
Megahertz The term mega can be considered
approximately 1 million. So therefore a
megahertz will be approximately 1 million cycles
within one second.   The term megahertz is to
identify CPU clock speed. It will determine how
fast that computer can process data. For
example a computer, which has a clock speed of
500MHz, can process 500 million bits of data
within one second.
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MIPS (Millions of Instructions Per Second)This
measures the number of instructions a
microprocessor is capable of performing in a
second. Once again, the higher the number, the
faster the processor.The table below shows the
main types of Intel microprocessor (up to the
Pentium MMX) with their speeds measured in
MIPS                                          
              While clock speed is the most
commonly used indicator of performance, it does
not always provide an accurate guide. For
example, a 486 processor with an internal clock
speed of 100Mhz will be slower than Pentium 90Mhz
or even 75Mhz, due to their different internal
architecture.
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INPUT Keyboard
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OUTPUT Printers
LASER
INK-JET
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LASER PRINTERS
Prior to printing, an electrostatic charge is
applied to a drum. Then laser beam paths to the
drum are altered by a spinning multisided
mirror. The reflected beams selectively remove
the electrostatic charge from the drum. Toner is
deposited on these portions of the drum. The drum
is rotated and the toner is fused to the paper to
create image.
INK-JET PRINTERS
Tiny droplets of ink, in either blue, red, yellow
or black, are positioned with great precision on
the paper to form characters and
images. Movement of the print heads and paper
are coordinated under program control.