Date post: | 24-Oct-2014 |
Category: |
Documents |
Upload: | sweetserin |
View: | 76 times |
Download: | 3 times |
B-Tech Lecture Notes Personal Computer Hardware
PCH-Module 1 http://btech-lecturenotes.blogspot.in/
Module 1: Introduction to Personal Computer
Hardware Components:
The following are the basic hardware components of a personal computer. They
are categorized according to their functions and use. Following components are most
commonly used pc hardware components and most commonly available components in
the market.
PC Hardware Components
1. Peripherals
a. Input/Output Devices
• Mouse
• Keyboard
• Touch Screen
• Joy Stick
• Monitor (CRT, LCD)
• Printers (Dot Matrix, Ink Jet, Laser Printer)
• Plotter
• Speakers
b. Disk Drives
• Floppy Disk
• Hard Disk
• CD – Compact Disc
• DVD – Digital Versatile Disc
• Blue Ray
• ZIP
c. SMPS – Switch Mode Power Supply
2. Logics
a. Mother Board
• Processor
• Processor Slot
B-Tech Lecture Notes Personal Computer Hardware
PCH-Module 1 http://btech-lecturenotes.blogspot.in/
o Slot Type
o Socket Type – Zero Insertion Force Socket
• Chip Set
o Clock Generator
o DMA Controller
• Co – Processor (currently built – in with main processor)
• Slots for Add – on – Cards (Bus Structures)
o ISA – Industry System Architecture
o EISA – Enhanced Industry Standard Architecture
o MCA – Micro Channel Architecture
o PCI – Peripheral Component Interconnect
o PCMCIA – Personal Computer Memory Card Industry Association
o VESA – Video Electronic Standard Association
o AGP – Accelerated Graphics Port
o USB – Universal Serial Bus
• Disk Interface
o Floppy Disk Interface
o Hard Disk/CD/DVD Interface
� IDE – Integrated Drive Electronics
� EIDE – Enhanced Integrated
� ATA – Advanced Technology Attachment
• Serial ATA
• Parallel ATA
� SCSI – Small Computer System Interconnect
� RAID – Redundant Array of Inexpensive Disks
• Communication Ports
o Serial
o Parallel
o Keyboard
o Mouse (PS/2)
o Display Port – VGA – Video Graphics Array
B-Tech Lecture Notes Personal Computer Hardware
PCH-Module 1 http://btech-lecturenotes.blogspot.in/
• viii. Memory
o ROM
� BIOS (CMOS) – Basic Input Output System
o RAM
� Package wise
• DIP – Dual – In line – Package
• SIMM – Single Inline Memory Module
• DIMM – Dual Inline Memory Module
� Technology wise
• EDO – Extended Data Out
• SD – Synchronous Dynamic
• DDR – Dual Data Rate
• Rambus
Study of motherboards:
• Processor
A processor is the logic circuitry that responds to and processes the basic
instructions that drive a computer. The term processor has generally replaced the term
central processing unit (CPU). The processor in a personal computer or that is embedded
in small devices is often called a microprocessor.
• Processor Slot
The term CPU socket (or CPU slot) is widely used to describe the connector
linking the motherboard to the Processor (CPU(s)) in certain types of desktop and server
computers, particularly those compatible with the Intel x86 architecture. Most CPU
sockets and processors in use today are built around the pin grid array (PGA)
architecture, in which the pins on the underside of the processor are inserted into the
socket. Normally socket is of two types.
o Slot Type
o Socket Type – Zero Insertion Force Socket
B-Tech Lecture Notes Personal Computer Hardware
PCH-Module 1 http://btech-lecturenotes.blogspot.in/
To aid installation, zero insertion force (ZIF) sockets are usually used, allowing
the processor to be inserted without any resistance, while gripping the pins firmly once
the processor is in place to ensure a reliable contact. An alternative to the PGA
architecture, used by several current and upcoming sockets, is the land grid array (LGA)
in which the pins reside on the socket rather than the CPU. The pins come into contact
with pads on the bottom of the processor. In contrast to CPU sockets, slot-based
processors and CPUs use a single-edged connection (similar to an expansion slot) rather
than a socket, and slot into the motherboard on their side. Slot architectures are rarely
used today.
• Chip Set
A group of chips on the motherboard that controls the timing and flow of data and
instructions to and from the CPU is known as chip set. One or more chips on a
motherboard that control the data flow between the processor, memory, and the other
components of the system. It consists of following chips.
o Clock Generator
o DMA Controller
• Co – Processor (currently built – in with main processor)
A separate chip (or nowadays, a portion of the CPU) that performs a lot of the
calculations and number crunching for the microprocessor, relieving the CPU of some of
its work and thus enhancing the overall speed of the system.
• Slots for Add – on – Cards (Bus Structures)
A slot is provided for additional cards to be added. Some of the cards are as
follows:-
o ISA – Industry System Architecture
ISA is an older technology for connecting computer peripherals (stands for
Industry Standard Architecture). Common current devices include modems and sound
cards. ISA is much slower than PCI, so PCI devices are generally better if you have a
B-Tech Lecture Notes Personal Computer Hardware
PCH-Module 1 http://btech-lecturenotes.blogspot.in/
choice. ISA is starting to fade and eventually will be removed entirely. Most
motherboards still come with at least one or two ISA slots on them.
o EISA – Enhanced Industry Standard Architecture
(Extended Industry Standard Architecture) This is an enhanced form of ISA,
which allows for 32-bit data transfers, while maintaining support for 8- and 16-bit
expansion boards. However, its bus speed, like ISA, is only 8 MHz. EISA is not widely
used, due to its high cost and complicated nature.
o MCA – Micro Channel Architecture
Micro Channel Architecture (hardware) is a 16/32 bits bus developed by IBM in
1986 for its PS/2 machines. It is not successful at all and IBM even uses it only for its
high level systems.
o PCI – Peripheral Component Interconnect
"Peripheral Component Interconnect" is a high-speed connection for devices
including SCSI cards, video cards, sound cards, modems, video capture cards, etc. This is
the primary way of adding devices to your computer. It is faster than ISA, so is preferred
for devices such as sound cards and SCSI cards. It is slower than AGP which is for
graphics cards only, so AGP graphics cards tend to be better than PCI ones. Default PCI
speed is 33 MHz.
o PCMCIA – Personal Computer Memory Card Industry Association
Personal Computer Memory Card International Association - A standardized
technology used to develop a expansion for portable devices (ie notebooks) In paging
these credit card sized devices support wireless connectivity. PCMCIA is an organization
consisting of some 500 companies that has developed a standard for small, credit card-
sized devices, called PC Cards. Originally designed for adding memory to portable
computers, the PCMCIA standard has been expanded several times and is now suitable
for many types of devices. There are in fact three types of PCMCIA cards. All three have
the same rectangular size but different widths
o VESA – Video Electronic Standard Association
Video Electronics Standards Association is a 32-bit local bus standard that is
compatible with both ISA and EISA cards. Many manufacturers of local bus adapters use
this standard because of its speed.
B-Tech Lecture Notes Personal Computer Hardware
PCH-Module 1 http://btech-lecturenotes.blogspot.in/
o AGP – Accelerated Graphics Port
Short for Accelerated Graphics Port, an interface specification developed by Intel
Corporation. AGP is based on PCI, but is designed especially for the throughput demands
of 3-D graphics. Rather than using the PCI bus for graphics data, AGP introduces a
dedicated point-to-point channel so that the graphics controller can directly access main
memory. The AGP channel is 32 bits wide and runs at 66 MHz.
o USB – Universal Serial Bus
USB is a "plug and play" interface between a computer and add-on devices such
camera and microphone. With USB, a device can be added to your computer without
having to turn the computer off. USB supports a data speed of 12 megabit per second.
This speed will accommodate MPEG video cameras.
• Disk Interface
The disk interface module provides support for handling transfers to and from the disk. It
consists of a priority ordered queue of block descriptors plus a thread that picks the first
descriptor off the queue and submits it to the disk device driver. The block descriptors
used by the disk module are the same as those used by the caches. Mainly there are two
disc interfaces in the mother board.
o Floppy Disk Interface
o Hard Disk/CD/DVD Interface
� IDE – Integrated Drive Electronics
This is a commonly used interface for hard disk drives and CD-ROM drives.
It is less expensive than SCSI, but offers slightly less in terms of performance.
� EIDE – Enhanced Integrated
A hardware interface which is faster than IDE, allows more memory, and can
connect up to four devices (such as hard drives, tape drives, and CD-ROM
drives) to the computer.
� ATA – Advanced Technology Attachment
It is a disk drive implementation that integrates the controller on the disk drive
itself. There are several versions of ATA, all developed by the Small Form
Factor (SFF) Committee: ATA : Also known as IDE (Integrated, or
B-Tech Lecture Notes Personal Computer Hardware
PCH-Module 1 http://btech-lecturenotes.blogspot.in/
Intelligent, Drive Electronics) supports one or two hard drives, a 16-bit
interface and PIO modes 0, 1 and 2. ATA-2 : Supports faster PIO modes (3
and 4) and multiword (DMA modes (1 and 2). ... there are two types of ATA.
� Serial ATA
� Parallel ATA
� SCSI – Small Computer System Interconnect
� There are two types of interfaces for hard drives, CD-ROM drives, etc.
One is SCSI, the other is IDE. IDE is much more common and less
expensive. SCSI is more expensive and also more flexible and generally
faster. With a single SCSI card you can have 15 or more devices whereas
you are only allowed to have 4 devices with an IDE system. The fastest
hard drives (and generally CD-ROM drives too) are SCSI-based. ... It is a
standard hardware interface that enables a variety of peripheral devices to
communicate with one another.
� RAID – Redundant Array of Inexpensive Disks
A collection of disk drives that offers increased performance and fault
tolerance. There are a number of different RAID levels. The three most
commonly used are 0, 1, and 5: Level 0: striping without parity (spreading out
blocks of each file across multiple disks). Level 1: disk mirroring or
duplexing. Level 2: bit-level striping with parity Level 3: byte-level striping
with dedicated parity. ... t is a subsystem storage concept designed for the
purpose of offering higher levels of protection from data loss that can occur
from any down time caused by malfunctions compared to the protection
offered by conventional disk drives. RAID arrays composed of conventional
discs can function for hundreds or even thousands of years without losing data
because of a disk failure. ...
• Communication Ports
o Serial
Port, or interface, that can be used for serial communication, in which only 1
bit is transmitted at a time. Most serial ports on personal computers conform
to the RS-232C or RS-422 standards. A serial port is a general-purpose
B-Tech Lecture Notes Personal Computer Hardware
PCH-Module 1 http://btech-lecturenotes.blogspot.in/
interface that can be used for almost any type of device, including modems,
mice, and printers (although most printers are connected to a parallel port).
o Parallel
It is an input/output connection on a computer that sends and receives
information in groups of eight bits (binary digits) at a time, traveling at high
speeds along parallel wires to a peripheral device such as a printer. The other
simple connection mechanism is a serial port, which transmits just one bit at a
time -- a data side road compared with a multi-lane motorway.
o Keyboard
o Mouse (PS/2)
o Display Port – VGA – Video Graphics Array
• Memory
o ROM
ROM is used to hold programs and data that must survive when the computer is
turned off. Because ROM is non-volatile; data in ROM will remain unchanged the
next time the computer is turned back on. As the name implies, data cannot be easily
written to ROM; depending on the technology used in the ROM, writing may require
special hardware, or may be impossible. A computer's BIOS may be stored in ROM.
BIOS (CMOS) – Basic Input Output System
BIOS stand for Basic Input/Output System, which controls the interface between
the video card and the computer. However, we are concerned with the System BIOS,
which is a collection of assembly language routines that allow programs and the
components of a PC to communicate with each other at the hardware level. It
therefore works in two directions and is active all the time your computer is switched
on, although these days it is bypassed by almost everything, typically anything 32-bit
in Windows. Software doesn't have to talk to a device directly; it calls a BIOS
routine, which does the job instead. Think of the BIOS as a mini operating system. So
BIOS can also be called Basic Initial Operating System. On an IBM-compatible PC,
you will find the BIOS embedded into a EEPROM on the motherboard, together with
hard disk utilities and a CMOS setup program. The BIOS information’s are stored in
a CMOS chip which is kept under constant voltage supply by the computer backup
B-Tech Lecture Notes Personal Computer Hardware
PCH-Module 1 http://btech-lecturenotes.blogspot.in/
battery. This way the information’s contained in the CMOS are always alive even if
the computer power is turned OFF..
PC and motherboard manufacturers make their own BIOSes (such as Compaq,
HCL, ACER etc.), but most tend to be based on code supplied by third party
companies, the most well-known of which are Award, American Megatrends (AMI).
Utilities that come with the BIOS, particularly diagnostic; POST (Power On Self
Test) and low-level format routines for the hard disk. The main menu to the BIOS
setup may contain the following heading: HARD DISK UTILITY or HDD LOW
LEVEL FORMAT. It allows you to low-level format the drive attached to your
computer. After the assembling the system and prior to the software installation the
first thing you have to do as soon as you boot the machine is set the CMOS.
BIOS stand for Basic Input/Output System, although the full term is used very
infrequently. The system BIOS is the lowest-level software in the computer; it acts as
an interface between the hardware (especially the chipset and processor) and the
operating system. The BIOS provides access to the system hardware and enables the
creation of the higher-level operating systems (DOS, Windows 95, etc.) that you use
to run your applications. The BIOS is also responsible for allowing you to control
your computer's hardware settings, for booting up the machine when you turn on the
power or hit the reset button, and various other system functions.
o RAM
Random Access Memory or RAM is a type of computer storage whose contents can
be accessed in any order. This is in contrast to sequential memory devices such as
magnetic tapes, discs and drums, in which the mechanical movement of the storage
medium forces the computer to access data in a fixed order. It is usually implied that
RAM can be both written to and read from, in contrast to Read-Only Memory or
ROM. RAM is categorized into following: -
� Package wise
o DIP – Dual – In line – Package
B-Tech Lecture Notes Personal Computer Hardware
PCH-Module 1 http://btech-lecturenotes.blogspot.in/
o SIMM – Single Inline Memory Module
o DIMM – Dual Inline Memory Module
� Technology wise
o EDO – Extended Data Out
o SD – Synchronous Dynamic
o DDR – Dual Data Rate
o Rambus
Types of Computer Expansion Slots [Written by Matthew Elton (copyright 2006
Matthew Elton)]
Expansion slots are located on the motherboard, and openings on the back of the
computer allow the ports on the cards that go in the slots to be accessed. The picture
below shows the SoundBlaster Live sound card, with additional ports attached to it
through an IDE cable. There are several types of expansion slots, including AGP, PCIe
(also known as PCIexpress), PCI, and ISA.
The top card of the SoundBlaster Live sound card plugs into a PCI expansion slot, while
the bottom card sends and receives its data to and from the larger card through an IDE
cable. The smaller card simply needs an empty spot in the case to be mounted to. It does
not need to be placed into an expansion slot on the motherboard.
B-Tech Lecture Notes Personal Computer Hardware
PCH-Module 1 http://btech-lecturenotes.blogspot.in/
Types of Expansion Slots:
• ISA
• AGP
• PCI
• PCIe, which is short for PCIexpress
ISA Slots
ISA slots are an older type of expansion slot, twice as big as PCI slots and slower than
PCI slots as well. ISA slots are usually black, while PCI slots are usually white. ISA
slots are not used much anymore, but most computers still have at least one of them.
ISA networking cards, ISA sound cards, ISA video cards, and other types of ISA
expansion cards can be used in the ISA slots.
PCI Slots
The photo above is a picture of a PCI expansion slot, the most common expansion slot.
PCI slots can handle 64 bits of data at a time, twice as fast as ISA slots, which can only
handle 32 bits of data at a time. PCI is an abbreviation for "Peripheral Component
Interconnect." A 64-bit PCI slot has 64 connections to the motherboard, and each
connection is capable of handling 1 bit of data at a time. A 32-bit ISA slot has 32
connections to the motherboard, each handling one bit of data at a time. (Note: Older
technology ISA slots are 8-bit and 16-bit. The newer EISA, (or Extended ISA), slots are
capable of 32-bit data transfer. Older PCI technology is 32-bit. The newer PCI
technology is 64-bit.). The diagram below shows how to properly insert a PCI card into
an empty PCI expansion slot.
B-Tech Lecture Notes Personal Computer Hardware
PCH-Module 1 http://btech-lecturenotes.blogspot.in/
As technology changes new expansion cards become available. These include video
cards, which allow a monitor to be connected to the computer, sound cards, which allow
speakers and a microphone to be connected to the computer, and networking cards, which
allow computers to be linked together. There are also many other types of expansion
cards. Below is a photograph of a Promise PCI expansion card. It allows you to connect
up to four additional drives to your computer with IDE cables. This expansion card
provides data transfer rates of up to 66,000,000 bits per second, (or 66Mbs/sec). This
technology is also known as Ultra ATA/66. ATA is an abbreviation for "Advanced
Technology Attachment." Ultra ATA/66 is also known as Ultra DMA/66. DMA is an
abbreviation for "Direct Memory Access." Ultra DMA/66 devices can directly access the
RAM, transferring 66 million bits of data per second.
B-Tech Lecture Notes Personal Computer Hardware
PCH-Module 1 http://btech-lecturenotes.blogspot.in/
Below is a picture of Creative Lab’s Sound Blaster Live Value PCI sound card. A sound
card is what processes sound and allows speakers and a microphone to be hooked up to
the computer. When you hear music coming from your computer's speakers, the sound
card's digital signal processor, also known as the DSP, is working together with the
digital-to-analog converter, also known as the DAC, processing and converting digital
sound data (electrical pulses represented by binary code) to analog sound data (increases
and decreases in electrical pulses that the speaker interprets and generates as increases
and decreases in tone, frequency, and volume.) When you talk into your computer's
microphone, the sound card's digital signal processor works along with the analog-to-
digital converter to process and convert analog sound data to digital sound data, which
can be saved onto your computers memory. Record players are analog – they are made
of tiny engravings that the needle moves through, that move back and forth in a wave
shape to change the frequency of the sound. Computers, however, are digital. A music
file stored on a computer hard drive is stored as a series of positive and negatively (north
and south) magnetically charged sectors on the hard drive. These are represented by 1s
and 0s in what is called binary code. Different sequences of these magnetic charges
instruct the computer to perform different tasks, and in this case, tell the computer what
frequencies and volumes to play when playing the music file.
B-Tech Lecture Notes Personal Computer Hardware
PCH-Module 1 http://btech-lecturenotes.blogspot.in/
Better sound cards have better sound, however, you can save a ton of money by just
buying a mediocre sound card online (I recommend www.newegg.com for those
interested in buying computer parts – there’s even better deals on neweggs older website,
just click on “Newegg Old Version” or something like that at the top right hand corner of
the homepage of newegg.com) The Sound Blaster Live Value card allows you to connect
a sound input device, like a CD-Player or radio, a microphone, front speakers, rear
speakers, and a joystick or MIDI instrument, like an MIDI keyboard. The front and rear
speakers can be combined together to produce stereo surround sound. Just like the video
card, the sound card uses its own little processor to process sound data.
Below is a picture of a SCSI (pronounced “sscuhzy”) PCI expansion card. SCSI is an
abbreviation for "Small Computer Interface System." With a SCSI expansion card, you
can connect up to fifteen devices to one SCSI connection. SCSI is one of the fastest data
transfer interfaces there is. SCSI cards are available with transfer rates up to 320 MB per
second! The Ultra320 SCSI-3 interface is the fastest SCSI interface, with a 320MB/sec
data transfer rate! Below is a picture of a PCI SCSI expansion card.
B-Tech Lecture Notes Personal Computer Hardware
PCH-Module 1 http://btech-lecturenotes.blogspot.in/
AGP Slots
The AGP expansion slot connects AGP video cards to the motherboard. The
video card shown above is an AGP GeForce FX 5500. Video cards are also known as
graphics cards. They process video and image data that will be displayed on your
screen. The monitor plugs into the video card. AGP is an abbreviation for Accelerated
B-Tech Lecture Notes Personal Computer Hardware
PCH-Module 1 http://btech-lecturenotes.blogspot.in/
Graphics Port. Most AGP video cards are capable of a higher data transfer rate than PCI
video cards. Video cards, like the one shown above, simply plug into an AGP slot and
connect a monitor or other video display device to a computer, usually through the VGA
port. The video card shown above has three different ports, for three different types of
monitors. The "DVI Out" connector connects to a “digital video display”. DVI is an
abbreviation for Digital Video Interface. Video cards with a TV output connection are
capable of displaying a computer's video on a television instead of a computer monitor,
which is great for playing movies on your computer. Unfortunately, most televisions
only support a very low resolution and refresh rate when hooked up to computers. Video
cards with a TV input connection are able of displaying a television's video on a
computer. This allows you to record television programs onto your computers hard
drive. The VGA connection is the standard connection to most monitors.
The quality of the display depends mostly on the type of video card, but also on
the type of monitor. There are many factors in determining how good a video card is, but
the most important, in my opinion, is video-RAM. Video cards have their own RAM,
called “video-RAM” and the more RAM the video card has the faster the video card, and
your computer, will run. Go to “Display Properties” from the control panel or by right
clicking on your desktop and clicking “Properties” and then click “Settings” and click
“Adapter” to see how much video RAM your current video card has. If you have less
then 128 megabytes of Video-RAM in your desktop, and you play a lot of computer
games, I would highly recommend upgrading to a video card with 128 megabytes of
video-RAM, such as the NVIDIA GeForce MX400 128Mb PCI, which goes in the PCI
expansion slot. I bought it for only fifty dollars online (it’s normally a hundred dollars in
stores but I got a great deal on it from www.newegg.com I recommend
www.newegg.com for those interested in buying computer parts – there’s even better
deals on neweggs older website, just click on “Newegg Old Version” or something like
that at the top right hand corner of the homepage of newegg.com). After upgrading from
a measly eight megabyte video card to the NVIDIA GeForce MX4000 128MB PCI video
card, my computer performed twice as fast! Games that used to take up to fifteen
minutes to load would load in seconds!
B-Tech Lecture Notes Personal Computer Hardware
PCH-Module 1 http://btech-lecturenotes.blogspot.in/
Anyway, let’s get back to talking about AGP cards. The photograph below shows what
an AGP expansion slot looks like.
AGP slots and cards come in four different modes, and you must be careful to match the
card and slot with the correct mode. Some AGP cards and AGP slots are capable of
running in more than one mode. AGP 1x mode is the oldest; it transfers data at 266MBs
per second. AGP 2x mode transfers data at 533megabytes per second. AGP 4x mode
transfers data at 1.07 gigabytes (1007 megabytes) per second. The latest AGP mode is
AGP 8x. It transfers data at 2.14gigabytes (2140 megabytes) per second!
Below is a picture of three PCI Express slots.
PCI EXPRESS
PCI Express is a new technology that is slowly replacing AGP. PCI Express x16 slots can
transfer data at 4GBs per second, which is about twice as fast as an AGP 8x slot! PCIe
stands for PCI Express, or PCIexpress. PCI Express slots come in five different sizes and
speeds: PCIe x1, PCIe x2, PCIe x4, PCIe x8, and PCIe x16. PCIe x16 slots are used for
graphics cards.
B-Tech Lecture Notes Personal Computer Hardware
PCH-Module 1 http://btech-lecturenotes.blogspot.in/
Monitor Connectors
HD15 15 pins in three rows, pins are skinnier than a usual
"DB" connector, thus it's got an "H" for High Density. Used
for PC's SVGA video cards and monitor cables.
DB15 15 pins in two rows, pins are just
like a DB9 or DB25. Used for Mac
monitors.
BNC connectors are used on Macs, Sun's and just about anything that's old
and good.
DB9 9 pins in two rows, used on older monitors, and VGA's.
PS/2 style Serial ports also use DB9 connectors.
13W3 a bunch of "DB" style pins and
three funny looking coax contacts. Used
on Sun and Mac monitors.
Other PC/Mac connectors
Parallel/Printer
CN36 (female) This is the connector you see on
the back of most printers.
CN36 (male) This is the connector used by most
printer cables.
DB25 (female) This connector is used for
parallel printer output on the PC. It is also used
for SCSI output, especially on the Mac.
DB25 (male) This is used for parallel printers (and
other parallel port devices) as well as SCSI and
serial ports. If you see a male on the back of your
B-Tech Lecture Notes Personal Computer Hardware
PCH-Module 1 http://btech-lecturenotes.blogspot.in/
computer, it is usually your COM2 serial port.
HPCN36 male This is the new "Type-C" IEEE-
1284 Parallel port connector which is used on
some new laser printers.
MINIDIN-8 (female) Serial Mac connector. Mac
Printers, Mac printer and modem outputs, etc.
Serial
DB25 serial connector. On a computer, this
would be a male not a female as pictured above.
DB9 serial connectors. On the computer there
should be a "male" connector, the mouse or other
serial device (modem, digital camera) would have a
female.
USB and Firewire connectors
"i.Link" connector. This is basically a 4-pin
Firewire/i.link/IEEE-1394 connector.
"Firewire" connector.This is a 6-pin Firewire/IEEE-
1394 connector.
USB type "A" connector. Connects to computer
or USB Hub.
USB type "B" connector. Connects to peripheral or
to USB Hub.
B-Tech Lecture Notes Personal Computer Hardware
PCH-Module 1 http://btech-lecturenotes.blogspot.in/
Mini USB connector used on many new USB
digital cameras.
Mini USB 2.0 connector used on many new USB
digital cameras.
Other connectors
S-Video connector, sometimes called S-VHS or
Y/C video. There're 4 little pins in there, it's
called a DIN4.
RCA (above) connector. Standard stereo connector.
3.5 mm Mini Phone Plug connector, (below) used on
computer sound cards.
SC connector, fiber optic network connector.
ST connector, fiber optic network connector.
MTRJ fiber optic network connector.
Toslink connector. Used for digital audio.
Different types of ports:
Ports are used to connect external devices to the computer. There exist several types of
ports like serial port, parallel port, USB port, AGP port. As the name suggests, the serial
port transfers data serially a bit at a time. As a result, the serial port needs only wire to
transmit 8 bits. The disadvantage is that it takes 8 times longer to transmit a byte. Also, it
is necessary to send a start bit before each byte of data, a stop bit after the byte to mark
the end of byte and a parity bit to help check the integrity of data. Serial ports come in the
form of 9-pin or 25-pin male connector. Serial ports are often known as communication
ports or RS232C ports. They are typically used to connect devices like mouse and
modem.
Parallel ports can send or receive a byte (8-bit) at a time. Unlike the serial port, these 8-
B-Tech Lecture Notes Personal Computer Hardware
PCH-Module 1 http://btech-lecturenotes.blogspot.in/
bits are transmitted parallel to each other. Parallel ports come in the form of 25-pin
female connector. Parallel ports are popularly used to connect printer, scanner, CD writer,
zip drive, external hard disk drive, tape backup drive, etc.
To spare the user botheration of 8-pin, 25-pin, male, female connectors, the USB has
been designed. It gives you a single, standardized, easy-to-use way to connect up to 127
devices to a computer. These devices include printers, scanners, mice, joystick, digital
camera, web cameras, speakers, telephones, zip drives, network connections, scientific
data acquisition devices, etc.
The AGP (Accelerated Graphics Port) port is used to connect to graphic card that
provides high-speed video performance typically required in games and other multimedia
applications.
Different types of add on cards:
o ISA – Industry System Architecture
ISA is an older technology for connecting computer peripherals (stands for
Industry Standard Architecture). Common current devices include modems and sound
cards. ISA is much slower than PCI, so PCI devices are generally better if you have a
choice. ISA is starting to fade and eventually will be removed entirely. Most
motherboards still come with at least one or two ISA slots on them.
o EISA – Enhanced Industry Standard Architecture
(Extended Industry Standard Architecture) This is an enhanced form of ISA,
which allows for 32-bit data transfers, while maintaining support for 8- and 16-bit
expansion boards. However, its bus speed, like ISA, is only 8 MHz. EISA is not widely
used, due to its high cost and complicated nature.
o MCA – Micro Channel Architecture
Micro Channel Architecture (hardware) 16/32 bits bus developed by IBM in 1986
for its PS/2 machines. It is not successful at all and IBM even uses it only for its high
level systems.
o PCI – Peripheral Component Interconnect
"Peripheral Component Interconnect" is a high-speed connection for devices
including SCSI cards, video cards, sound cards, modems, video capture cards, etc. This is
B-Tech Lecture Notes Personal Computer Hardware
PCH-Module 1 http://btech-lecturenotes.blogspot.in/
the primary way of adding devices to your computer. It is faster than ISA, so is preferred
for devices such as sound cards and SCSI cards. It is slower than AGP which is for
graphics cards only, so AGP graphics cards tend to be better than PCI ones. Default PCI
speed is 33 MHz.
o PCMCIA – Personal Computer Memory Card Industry Association
Personal Computer Memory Card International Association - A standardized
technology used to develop a expansion for portable devices (ie notebooks) In paging
these credit card sized devices support wireless connectivity. PCMCIA is an organization
consisting of some 500 companies that has developed a standard for small, credit card-
sized devices, called PC Cards. Originally designed for adding memory to portable
computers, the PCMCIA standard has been expanded several times and is now suitable
for many types of devices. There are in fact three types of PCMCIA cards. All three have
the same rectangular size but different widths
o VESA – Video Electronic Standard Association
Video Electronics Standards Association is a 32-bit local bus standard that is
compatible with both ISA and EISA cards. Many manufacturers of local bus adapters use
this standard because of its speed.
o AGP – Accelerated Graphics Port
Short for Accelerated Graphics Port, an interface specification developed by Intel
Corporation. AGP is based on PCI, but is designed especially for the throughput demands
of 3-D graphics. Rather than using the PCI bus for graphics data, AGP introduces a
dedicated point-to-point channel so that the graphics controller can directly access main
memory. The AGP channel is 32 bits wide and runs at 66 MHz.
o USB – Universal Serial Bus
USB is a "plug and play" interface between a computer and add-on devices such
camera and microphone. With USB, a device can be added to your computer without
having to turn the computer off. USB supports a data speed of 12 megabit per second.
This speed will accommodate MPEG video cameras.
B-Tech Lecture Notes Personal Computer Hardware
PCH-Module 1 http://btech-lecturenotes.blogspot.in/
Power supply in PC:
If there is any one component that is absolutely vital to the operation of a computer, it is
the power supply. Without it, a computer is just an inert box full of plastic and metal. The
power supply converts the alternating current (AC) line from your home to the direct
current (DC) needed by the personal computer. In this article, we'll learn how PC power
supplies work and what the wattage ratings mean.
Your Browser Does Not Support iFrames
Power Supply
In a personal computer (PC), the power supply is the metal box usually found in a corner
of the case. The power supply is visible from the back of many systems because it
contains the power-cord receptacle and the cooling fan.
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 amperes or amps. If you
have been around PCs for many years, you probably remember that the original PCs had
large red toggle switches that had a good bit of heft to them. When you turned the PC on
or off, you knew you were doing it. These switches actually controlled the flow of 120
volt power to the power supply.
Today you turn on the power with a little push button, and you turn off the machine with
a menu option. These capabilities were added to standard power supplies several years
ago. The operating system can send a signal to the power supply to tell it to turn off. The
push button sends a 5-volt signal to the power supply to tell it when to turn on. The
B-Tech Lecture Notes Personal Computer Hardware
PCH-Module 1 http://btech-lecturenotes.blogspot.in/
power supply also has a circuit that supplies 5 volts, called VSB for "standby voltage"
even when it is officially "off", so that the button will work.
This is a power supply removed from its PC case. The small, red
switch at right, above the power-cord connector, is for changing line
voltages in various countries.
The interior of a power supply.
B-Tech Lecture Notes Personal Computer Hardware
PCH-Module 1 http://btech-lecturenotes.blogspot.in/
Switcher Technology
Prior to 1980 or so, power supplies tended to be heavy and bulky. They used large, heavy
transformers and huge capacitors (some as large as soda cans) to convert line voltage at
120 volts and 60 hertz into 5 volts and 12 volts DC.
The switching power supplies used today are much smaller and lighter. They convert the
60-Hertz (Hz, or cycles per second) current to a much higher frequency, meaning more
cycles per second. This conversion enables a small, lightweight transformer in the power
supply to do the actual voltage step-down from 110 volts (or 220 in certain countries) to
the voltage needed by the particular computer component. The higher-frequency AC
current provided by a switcher supply is also easier to rectify and filter compared to the
original 60-Hz AC line voltage, reducing the variances in voltage for the sensitive
electronic components in the computer.
In this photo you can see three small transformers (yellow) in the
center. To the left are two cylindrical capacitors. The large finned
pieces of aluminum are heat sinks. The left heat sink has transistors
attached to it. These are the transistors in charge of doing the
switching -- they provide high-frequency power to the transformers.
Attached to the right heat sink are diodes that rectify AC signals and
turn them into DC signals.
B-Tech Lecture Notes Personal Computer Hardware
PCH-Module 1 http://btech-lecturenotes.blogspot.in/
A switcher power supply draws only the power it needs from the AC line. The typical
voltages and current provided by a power supply are shown on the label on a power
supply.
Personal computer power supply label.
VSB is the standby voltage provided to the power
switch.
Switcher technology is also used to make AC from DC, as found in many of the
automobile power inverters used to run AC appliances in an automobile and in
uninterruptible power supplies. Switcher technology in automotive power inverters
changes the direct current from the auto battery into alternating current. The transformer
uses alternating current to make the transformer in the inverter step the voltage up to that
of household appliances (120 VAC).
How an SMPS works
B-Tech Lecture Notes Personal Computer Hardware
PCH-Module 1 http://btech-lecturenotes.blogspot.in/
Block diagram of a mains operated AC-DC SMPS with output voltage regulation.
Input rectifier stage
AC, half-wave and full wave rectified signals
If the SMPS has an AC input, then its first job is to convert the input to DC. This is called
rectification. The rectifier circuit can be configured as a voltage doubler by the addition
of a switch operated either manually or automatically. This is a feature of larger supplies
to permit operation from nominally 120 volt or 240 volt supplies. The rectifier produces
an unregulated DC voltage which is then sent to a large filter capacitor. The current
drawn from the mains supply by this rectifier circuit occurs in short pulses around the AC
B-Tech Lecture Notes Personal Computer Hardware
PCH-Module 1 http://btech-lecturenotes.blogspot.in/
voltage peaks. These pulses have significant high frequency energy which reduces the
power factor. Special control techniques can be employed by the following SMPS to
force the average input current to follow the sinusoidal shape of the AC input voltage
thus the designer should try correcting the power factor. A SMPS with a DC input does
not require this stage. A SMPS designed for AC input can often be run from a DC supply,
as the DC passes through the rectifier stage unchanged. (The user should check the
manual before trying this, though most supplies are quite capable of such operation even
though no clue is provided in the manual!)
If an input range switch is used, the rectifier stage is usually configured to operate as a
voltage doubler when operating on the low voltage (~120 VAC) range and as a straight
rectifier when operating on the high voltage (~240 VAC) range. If an input range switch
is not used, then a full-wave rectifier is usually used and the downstream inverter stage is
simply designed to be flexible enough to accept the wide range of dc voltages that will be
produced by the rectifier stage. In higher-power SMPSs, some form of automatic range
switching may be used.
Inverter stage
The inverter stage converts DC, whether directly from the input or from the rectifier stage
described above, to AC by running it through a power oscillator, whose output
transformer is very small with few windings at a frequency of tens or hundreds of
kilohertz (kHz). The frequency is usually chosen to be above 20 kHz, to make it
inaudible to humans. The output voltage is optically coupled to the input and thus very
tightly controlled. The switching is implemented as a multistage (to achieve high gain)
MOSFETs amplifier. MOSFETs are a type of transistor with a low on-resistance and a
high current-handling capacity. This section refers to the block marked "Chopper" in the
block diagram.
Voltage converter and output rectifier
If the output is required to be isolated from the input, as is usually the case in mains
power supplies, the inverted AC is used to drive the primary winding of a high-frequency
transformer. This converts the voltage up or down to the required output level on its
secondary winding. The output transformer in the block diagram serves this purpose.
B-Tech Lecture Notes Personal Computer Hardware
PCH-Module 1 http://btech-lecturenotes.blogspot.in/
If a DC output is required, the AC output from the transformer is rectified. For output
voltages above ten volts or so, ordinary silicon diodes are commonly used. For lower
voltages, Schottky diodes are commonly used as the rectifier elements; they have the
advantages of faster recovery times than silicon diodes (allowing low-loss operation at
higher frequencies) and a lower voltage drop when conducting. For even lower output
voltages, MOSFET transistors may be used as synchronous rectifiers; compared to
Schottky diodes, these have even lower "on"-state voltage drops.
The rectified output is then smoothed by a filter consisting of inductors and capacitors.
For higher switching frequencies, components with lower capacitance and inductance are
needed.
Simpler, non-isolated power supplies contain an inductor instead of a transformer. This
type includes boost converters, buck converters, and the so called buck-boost converters.
These belong to the simplest class of single input, single output converters which utilise
one inductor and one active switch (MOSFET). The buck converter reduces the input
voltage, in direct proportion, to the ratio of the active switch "on" time to the total
switching period, called the Duty Ratio. For example an ideal buck converter with a 10V
input operating at a duty ratio of 50% will produce an average output voltage of 5V. A
feedback control loop is employed to maintain (regulate) the output voltage by varying
the duty ratio to compensate for variations in input voltage. The output voltage of a boost
converter is always greater than the input voltage and the buck-boost output voltage is
inverted but can be greater than, equal to, or less than the magnitude of its input voltage.
There are many variations and extensions to this class of converters but these three form
the basis of almost all isolated and non-isolated DC to DC converters. By adding a
second inductor the Ćuk and SEPIC converters can be implemented or by adding
additional active switches various bridge converters can be realised.
Other types of SMPS use a capacitor-diode voltage multiplier instead of inductors and
transformers. These are mostly used for generating high voltages at low currents. The low
voltage variant is called charge pump.
Regulation
A feedback circuit monitors the output voltage and compares it with a reference voltage,
which is set manually or electronically to the desired output. If there is an error in the
B-Tech Lecture Notes Personal Computer Hardware
PCH-Module 1 http://btech-lecturenotes.blogspot.in/
output voltage, the feedback circuit compensates by adjusting the timing with which the
MOSFETs are switched on and off. This part of the power supply is called the switching
regulator. The "Chopper controller" shown in the block diagram serves this purpose.
Depending on design/safety requirements, the controller may or may not contain an
isolation mechanism (such as opto-couplers) to isolate it from the DC output. Switching
supplies in computers, TVs and VCRs have these opto-couplers to tightly control the
output voltage.
Open-loop regulators do not have a feedback circuit. Instead, they rely on feeding a
constant voltage to the input of the transformer or inductor, and assume that the output
will be correct. Regulated designs work against the parasitic capacity of the transformer
or coil, monopolar designs also against the magnetic hysteresis of the core.
The feedback circuit needs power to run before it can generate power, so an additional
non-switching power-supply for stand-by is added.
Power factor
Early switched mode power supplies incorporated a simple full wave rectifier connected
to a large energy storing capacitor. Such SMPS draws current from the AC line in short
pulses when the mains instantaneous voltage exceeds the voltage across this capacitor.
During the remaining portion of the AC cycle the capacitor provides energy to the power
supply. As the result, input current of such basic switched mode power supplies has high
harmonics content and relatively low power factor. This creates extra load on utility lines,
increases heating of the utility transformers, and may cause stability problems in some
applications such as in emergency generator systems or aircraft generators. In 2001 the
European Union put into effect the standard IEC/EN61000-3-2 to set limits on the
harmonics of the AC input current up to the 40th harmonic for equipment above 75W.
The standard defines four classes of equipment depending on its type and current
waveform. The most rigorous limits (class D) are established for personal computers,
computer monitors, and TV receivers. In order to comply with these requirements
modern switched-mode power supplies normally include an additional power factor
correction (PFC) stage.
Types
Switched-mode power supplies can be classified according to the circuit topology.
B-Tech Lecture Notes Personal Computer Hardware
PCH-Module 1 http://btech-lecturenotes.blogspot.in/
• Buck converter (single inductor; output voltage < input voltage)
• Boost converter (single inductor; output voltage > input voltage)
• buck-boost converter (single inductor; output voltage can be more or less than the
input voltage)
• flyback converter (uses output transformer; allows multiple outputs and input-to-
output isolation)
o typical Power: 0 to ca. 150 W
o relative cost: 100%
Applications
Switched-mode PSUs in domestic products such as personal computers often have
universal inputs, meaning that they can accept power from most mains supplies
throughout the world, with rated frequencies from 50 Hz to 60 Hz and voltages from 100
V to 240 V (although a manual voltage "range" switch may be required). In practice they
will operate from a much wider frequency range and often from a DC supply as well. In
2006, Intel proposed the use of a single 12 V supply inside PCs, due to the high
efficiency of switch mode supplies directly on the PCB.
Cars, trucks, telecom lines, and production plants, but not planes, supply DC to avoid
hum and ease the integration of capacitors and batteries used to buffer the voltage.
In the case of TV sets, for example, one can test the excellent regulation of the power
supply by using a variac. For example, in some models made by Philips, the power
supply starts when the voltage reaches around 90 volts. From there, one can change the
voltage with the variac, and go as low as 40 volts and as high as 260, and the image will
show absolutely no alterations.