COMPUTER-HARDWARE - Info Poster

clashjudiciousΗλεκτρονική - Συσκευές

8 Νοε 2013 (πριν από 3 χρόνια και 11 μήνες)

94 εμφανίσεις

COMPUTE
R
HARDWARE

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CONTENTS

MOTHERBOARD


ROM
-
CHIP


CMOS


BIOS


POST


SYSTEM BUS


INTERRUPTS

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Introduction to the PC


A computer is a device or set of devices which work
under the control stored program (which can be
changed ), automatically accepting and processing
data to produce information


Mainframes


are the very largest computers
-

million dollar
machines, which can occupy more than one room,
An example is IBM model 390.



Minicomputers

are large powerful machines. They typically serve a

network of simple terminals. IBM's AS/400 is an

example of a minicomputer.



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Workstations


are powerful user machines. They have the
power to handle complex engineering
applications. They use the UNIX or sometimes
the NT operating system. Workstations can be
equipped with powerful RISC processors like
Digital Alpha or MIPS.



PC's

are the Benjamin's in this order: Small
inexpensive, mass produced computers. They
work on DOS, Windows, or similar operating
systems. They are used for standard
applications.


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The PC consists of a central unit (referred to as
the computer) and various peripherals. The
computer is a box, which contains most of the
working electronics. It is connected with cables
to the peripherals.

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MAINFRAME
COMPUTER

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MINICOMPUTE
R

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PC`s

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System Resources

PCs have four types of system resources:



Interrupt Request (IRQ) lines,


Storage,


I/O ports,


and memory ranges.


Many system components and peripherals require
one or more of these resources, which raises the
twin problems of resource availability and resource
conflicts. Resource availability is particularly
important with regard to IRQs, which are in high
demand, and of which only 16 exist. Resource
conflicts can occur when two devices are assigned
the same resource, in which case one or both
devices may not function, or may function
unpredictably. Resource conflicts may occur even
with plentiful resources, such as I/O ports, where
many are available and only a few are in use.

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PERIPHALS DEVICE

Peripherals devices can be
external such Mouse,
Keyboard, Monitor, External
-
Zip drive or scanner or
internal such as a CD
-
ROM
drive or internal Modern.

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Processor Speed



Amount of Memory



Hard
-
disk free Space



System bus speed



Graphic acceleration Cards(Video
Cards)



SYSTEM PERFORMANCE

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MOTHERBOARD(MAIN
BOARD)



The motherboard is also called the system
board or the main board. Everything else
in the system plugs into, is controlled by,
or depends on the motherboard to
communicate with other devices on the
system. The system board is the largest
of the printed circuit boards. Every
system has one.

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ATX MortherBoard

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The system board generally houses
the following components


The CPU


The controller circuitry


The bus


The RAM


The expansion slots for additional boards


The ports for external devices


The Complementary Metal
-
Oxide Semiconductor
(CMOS, pronounced C moss)



The other Read Only memory (ROM)



The BIOS chips


The support chips providing varied functionality


Jumpers

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There are TWO type of Motherboard

1. AT

2. ATX


(Advanced Technology EXtended motherboard) The PC
motherboard that superseded the Baby AT design. The
ATX layout rotated the CPU and memory 90 degrees,
allowing full
-
length expansions to be plugged into all
sockets. The power supply blows air over the CPU rather
than pulling air through the chassis.



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When you turn power on, several things happen
in the PC:

You hear the fan motor starting. There are one or
more cooling fans in the PC. They produce a
whirring sound.

After a few seconds, text starts to scroll on the
screen.

Now the PC tests and counts the RAM. You see a
number on the screen. It increases in size.

THE Pc START
-
UP PROCESS

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To understand the working of the PC, it is useful to
study the PC start
-
up process. Those are events, which
take place from power
-
on until the PC is ready to work.
Remember, the PC can do nothing without receiving
instructions. These instructions are commands, which
are sent to the CPU. During start
-
up, the PC reads the
commands in this sequence:

Cont…….

First it receives commands from the ROM
chips. Those chips are

inherent in any computer. They contain the
POST

and

BIOS

instructions, which we will look at shortly.

Next, the operating system is read from the
hard disk
(or from floppy drive A). This is called
the boot process.

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ROM (
Read Only Memory)
. The ROM chips are on

the system board. They contain.
system software
.

System software are

instructions, which enable the PC to coordinate the

functions of various computer components.

The ROM chips contain instructions, which are

specific for that particular system board. Those

instructions will remain in the

PC throughout its life. They will usually not be

altered. Primarily, they are
start
-
up instructions.


The ROM chips


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start
-
up instructions. For most users, they are all

woven together. You can differentiate between:

POST
(Power On Self Test)

The
Set
-
up
instructions
, which connect with the

CMOS instructions

BIOS instructions
, which connect with the various

hardware peripherals

The
Boot
instructions
, which calls the operating

system (DOS, OS/2, or Windows,Linux)

All these instructions are in ROM chips, and they

are activated on by one during start
-
up.

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POST


Power On Self Test

is the first
instruction executed
during start
-
up.

It checks the PC
components and that
everything works.

You can recognize it
during the RAM test,
which occurs as soon as
you turn power on.

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If POST detects errors in the system,
it will write error messages on the
screen.

If the monitor is not ready, or if the
error is in the video card, it will also
sound a pattern of beeps (for
example 3 short and one
long) to identify the error to the
user.



*POST also reads those user
instructions,

which are found in
CMOS:

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For example, POST cannot by itself find
sufficient information about the floppy
drive(s).


Floppy drives are so "dumb," that POST
cannot read whether they are floppy drives
or not, nor what type. About the same
goes for IDE hard disks, while EIDE hard
disks are a little more "intelligent,"
However, POST still needs assistance to
identify

them
100
% correctly. The same goes for
RAM:


POST can count how much RAM is in the

PC. However, POST cannot detect whether
it is FPM,EDO or SD RAM. Since the CPU
and BIOS reads data from RAM chips
differently, depending on the RAM type,
that type must be identified.

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CMOS

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CMOS
(Complimentary Metal Oxide
Semiconductor)

is a small amount of
memory in a special RAM chip. Its memory is
maintained with electric power from a small
battery.

Certain system data are stored in this chip.
They must be read to make the PC operable.

There may be
100
to
200
bytes of data
regarding
DATE
,
TIME
,
FLOPPY

and
HARD
DISK DRIVER,

and much more.


CMOS data can be divided in
two

groups:



Data, which POST can find during
the system test.


Data, which contain user options.


CMOS battery Cont…………

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The start the BIOS programs are from a
ROM chip. BIOS abbreviation of
(Basic
Input/Output System)

and those are
programs, which are linked to specific
hardware systems.

Is typically placed in a Rom
chip that come with computer.


It contains the program code required to
control all the basic operating
components of the computer system. In
other words, the BIOS contains the
software required to test hardware at boot
up, load the operating system, and
support the transfer of data between
hardware components.

BIOS

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The BIOS programs control hardware, the
user (programmer) controls hardware via
a call to BIOS.


BIOS typically occupy
1
MB, and the
programs are saved ROM chip on the
system board.

During start
-
up, BIOS is read from ROM
chips.That information is supplemented
with the system data saved in CMOS.

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PORTS

PC PORTs

The Pc user a number of different connector or
ports to attach input, output and input/output.

SERIAL PORT

Transmits data one bit at a time and can do so in
both direction .A single wire is used for
transmitted data and another wire for received
data normally used nine
-
pin connector.

TYPE OF PORTS


SERIAL PORT


PARALLEL PORT

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PARALLEL PORT

Transmits many bits at once. In modern PCs
the single parallel port carries 8
-
bits signals
so that a whole byte can be sent at once.


UNIVERSAL SERIAL BUS (USB)


This is a relatively new form of connector. It
utilies a rectangular plug providing a high speed
serial connection.

Expandability:USB allow u to daisy chain up to
127
devices

Support PnP

Allow hot swapping

Cable length:
15
feet
15
m.


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SYSTEM BUS

System
-
bus connects together
Processor, Main
-
Memory and I/O
-
Controllers.

Data could travel (usually 32
-
bits side
-
by
-
side i.e. in bit
-
wise parallel), a
pathway along which the address
specifying a particular desired memory
location could travel, and a few other
lines which would tell the memory
whether to store (write) or retrieve

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The busses are the PC`s express way. They
are “wires ” on the circuit board, which
transmit data between different
components. One “wire” can move one bit
at a time


The data flow on the system board,


u will find the CPU, which is the
“brain” of the PC and the busses.


The busses are the nerve system of
system system
-
board. They connect
the CPU to all other
components.There are least at three
busses.


Data
-
Bus


Control
-
Bus


Address
-
Bus

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Control Bus


Is bidirectional bus, meaning that signal can be carried in
both directions.

Typical control lines include:

Memory write:

To send data to memory

Memory Read:
To send data to from memory.

I/O write:
To send data to be output to specific I/O port.

I/O read:

To send data from a specific I/O port

Bus request
-

When a component is requesting control
of the






system bus.

Interrupt request:

To indicate that an interrupt is
pending

Interrupt acknowledge:

to confirm that an interrupt
has been










acknowledged

Clock:

To synchronies operations

Reset:
Initializes all the components.

Transfer acknowledges confirming that transferred either on or off the data bus.

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DATA BUS

Typical data bus consists of
8
,
16
or
32
separate lines. Moving data and
instructions between system
components.

ADDRESS BUS

When process wishes to read a word
of data from memory, it first puts
the address of the required word on
the address bus


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Is a signal from one device /source
seeking the attention of the processor.
Signal to indicate that attention from the
processor is required.


INTERRUPT


If interrupt an enabled, on receipt of an
interrupt the currently executing program
is suspended in an orderly fashion and
control is passed to an interrupt service
routine

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There are least are four type of an interrupts;


PROGRAM

Generated by a times within the
processor to allow the operating
system to perform certain function at
regular interval of time.


TIMES


Generated by some condition that
occurs as a result of an instruction
execution or attempt to execute an
illegal machine instruction.

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I/O

Generated by I/O controller to signal
normal completion of an operation or to
signal a variety of error condition

HARDWARE FAILURE

Generated by a failure such as
power failure on memory parity
error.

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