Lesson 4
Connector Components
Serial and Parallel Ports
• All peripheral devices that
connect to the computer use
connectors on the back of the
computer known as ports.
• A serial port can be used to
connect devices that use a
serial interface such as a
modem, scanner, mouse, etc.
• A parallel port is a socket on
the computer that is used to
connect a printer or other
peripheral device such as a
portable hard disk, tape
backup, scanner, or a CDROM.
PS/2 Ports/ 6-pin Mini DIN, 5pin DIN
• PS/2 keyboard or PS/2 mouse
ports are used to connect the
PC to its keyboard and mouse.
Universal Serial Bus (USB) and
FireWire
• The Universal Serial Bus (USB) is an
external port and allows user to
connect up to 127 external PC
peripherals, including USB
keyboards, mice, printers, modems,
scanners, and external disk drives.
• FireWire, also known as i.LINK or
IEEE 1394 is a high-speed, platformindependent communication bus that
interconnects digital devices such as
digital video cameras, printers,
scanners, digital cameras, and hard
drives.
IDE, EIDE, Ultra,
and SCSI Controllers
• The internal hard drive is
connected to a disk
controller with a cable.
• The hard drive and other
devices can use one of two
types of interface controllers
to work with the computer.
• These include the
Enhanced Integrated Drive
Electronics (EIDE), and
Small Computer System
Interface (SCSI,
pronounced "scuzzy")
connections.
IDE, EIDE, Ultra,
and SCSI Controllers (cont.)
• Integrated Drive Electronics (IDE) is a type of hardware
interface widely used to connect hard disks, CD-ROMs,
and tape drives to a PC.
• 20 GB IDE hard disks have become entry level.
• The IDE interface is officially known as the AT Attachment
(ATA) specification.
• Enhanced IDE (EIDE) or ATA-2 disk drives is the "new and
improved" IDE. The EIDE interface can handle up to 8.4
GB or more.
• Ultra ATA disk drives are typically much faster than the
older ATA and ATA-2 disk drives.
• Typical Ultra drive sizes can go up to 50 GB or more.
IDE, EIDE, Ultra,
and SCSI Controllers (cont.)
•
•
•
SCSI devices have the controlling electronics on each of
the drives. However, SCSI is a much more advanced
interface controller than ATA-2/EIDE. It is ideal for highend computers, including network servers.
SCSI devices are typically connected in a series, forming
a chain that is commonly referred to as a daisy chain.
There are three types of SCSI termination :
1. Passive
2. Active
3. Forced Perfection
SCSI Disk Types
• Three major versions of the
SCSI standard are currently
on the market, SCSI-1,
SCSI-2, and SCSI-3.
• To help identify the
signaling system used by
SCSI devices (controllers
and drives), a system of
symbols has been devised
to identify the different
signaling systems.
SCSI Disk Types (cont.)
• SCSI-1, was used by many Apple
computers in the early 1980s. By
today’s standards it was rather
slow.
• SCSI-2 uses two different signaling
systems, known as single-ended
interface and differential interface.
The two signaling systems are
incompatible and cannot be mixed
on the same SCSI bus.
• This figure shows an example of a
50-pin, 68-pin, and 80-pin (SCA)
connector.
• SCSI-3 is the latest standard of the
SCSI family. It combines all the best
features of the previous SCSI
standards.
Storage Components
Floppy Drives
• A Floppy Disk Drive (FDD)
magnetically reads and
writes information onto
floppy diskettes, which are
a form of removable storage
media.
• The main drawback to the
floppy diskette is that it only
holds 1.44 MB of
information, although most
PCs still have a floppy
drive.
The Hard Drive
• The HDD has a much
larger storage capacity
than the floppy for longterm storage.
• It stores programs and
files, as well as the
operating system.
• Typically, the HDD is an
internal drive that
cannot be removed
from the computer.
The Hard Drive (cont.)
• Hard Drive
Components include:
disk platters, read/write
heads, head actuator
assembly, spindle
motor, logic/circuit
board, bezel/faceplate,
configuration jumpers,
and interface
connectors.
The Hard Drive (cont.)
• Disk platters are the actual
media on which data is stored in
the hard disk drive.
• A hard disk drive typically has
two to ten platters. They are
usually either 2 ½” or 3 ½” in
diameter and are typically
constructed of aluminum or a
glass-ceramic composite
material.
• Platters are stacked with spaces
between them on a hub that
holds them in position, separate
from one another.
• The hub is also called the
spindle.
The Hard Drive (cont.)
• The hard disk drive functions in much the
same way as a floppy disk drive.
• The disk platters spin at a high speed while
the drive heads access the media to conduct
read or write operations.
• Personal computers have at least one HDD
installed inside the system unit.
• If more storage capacity is needed, another
HDD can usually be added.
• The capacity of the HDD is a measure of how
much information it can store.
CD-ROMs
• A CD-ROM drive is a secondary
storage device that reads
information stored on a compact
disc. The CD-ROM is an optical
media.
• They are used for installing
programs, running applications
that install some of the files to the
hard drive, and executing the
program by transferring the data
from the CD-ROM to memory
while the program is running
• The major components within a
CD-ROM drive are the optical
head assembly, head actuator
mechanism, spindle motor, loading
mechanism, connectors and
jumpers, and logic board.
CD-ROMs (cont.)
• Data is stored in the form of
indentations and bumps on the
reflective surface of every CDROM disk.
• The indentations are called pits,
and the bumps are called lands.
• The most important specification
for a CD-ROM drive is its speed,
or how fast the disc will spin. The
faster the disc spins, the faster
the data can be transferred to
the computer’s memory.
• Two other important
specifications to consider are the
access time and data transfer
rate.
DVD - DVDRW
• The DVD looks like a CD,
but the storage capacity is
significantly higher.
• For this reason, many
software manufacturers are
starting to put programs,
manuals, and other
documentation on one DVD
instead of multiple CDs.
• Recordable DVD drives will
become standard on
computer systems just like
the CD drive did.
Backup Hardware
• Tape drives are most
commonly used as the
device for data backup on a
network server disk drive.
There are a variety of tape
devices that use different
tape formats for storing
data.
• New USB storage devices
can easily save and access
16MB, 32MB, 64MB,
128MB, 256MB, 512MB
and 1GB.
Network Components
Modems
• A modem is the primary
way to connect to the
Internet with Windows 9x
through a dialup networking
connection.
• A modem is a device that
converts the digital data
used by computers into
analog signals that is
suitable for transmission
over a telephone line, and
converts the analog signals
back to a digital signal at
the destination.
Network Interface Card (NIC)
• A Network Interface Card
(NIC), is used to connect a
local computer to a group of
other computers so they can
share data and resources in a
networked environment.
• All network interface cards are
designed to use Ethernet,
Token Ring, or another similar
protocol.
Network Interface Card (NIC)
cont.
• NICs come in form of
expansion cards (PCI or
ISA) that can be installed in
one of the computers
expansion slots.
• The network cable plugs to
the computer through the
adapter card or NIC.
• This is possible due to a
connector type known as
the RJ-45 connector it has 8
wires inside.
System Resources
What are System Resources?
• System resources are shared
between the different hardware
components or devices of the
computer system that need to
communicate with CPU.
• The CPU is a complete
computation engine that is
fabricated on a single chip.
• It not only controls the functions
of the computer, but also handles
requests from many input and
output devices.
• The CPU is only capable of
handling one request at a time.
Interrupt Requests (IRQ's)
• Various hardware devices may
want to tell the CPU that they
have some information
available that is ready for
transfer. The devices indicate
this by making an interrupt
request, or IRQ.
• It is a general rule that IRQ’s
cannot be shared.
• A device's IRQ will cause the
operating system to stop
momentarily as it asks the
CPU to service its request.
Direct Memory Access (DMA)
• Direct Memory Access (DMA)
channels allow devices to
bypass the processor and
directly access the computer
memory.
• DMA channels are typically
used by high-speed
communication devices for
transferring large amounts of
data at high speeds.
• Examples include sound
cards, some network cards,
some SCSI cards, some disk
drives, and some tape backup
drives.
Input/Output (I/O) Addresses
• An I/O port number is a
memory address where data
is temporarily stored as it
moves in and out of the
devices.
• The I/O address is very similar
to a post office box. As mail
comes in, it is stored
temporarily in a post office
box. No two boxes can have
the same number or the mail
can end up in the wrong box.
• No two devices can have the
same I/O address.
Portable Devices
Notebook Computers
• Notebook computers
incorporate the system unit,
input unit, and output unit
into a single, lightweight
package, that can be
carried around by the user.
• They are also called
portables, laptop
computers, palmtops, or
personal digital assistant
(PDA), depending on their
size and what they can do.
Portable Hardware
• Portables are built with the
intention of being
lightweight and fitting within
a certain size or form factor.
• Portable devices include
batteries, hard drives,
PCMCIA Cards, and
memory.
• Originally, portables used
Nickel Cadmium (Ni-Cad)
batteries and were in an
external battery pack that
would attach to the portable
device.
Portable Hardware (cont.)
• More recently, Nickel MetalHydride (NiMH) and LithiumIon batteries have been used
in portable devices.
• These batteries usually last for
a little over two hours,
depending on their size and
the power consumption by the
device.
• Hard drives have been
developed to be smaller and
use less power to
accommodate size and power
limitations.
PCMCIA Cards
•
•
The Personal Computer Memory
Card International Association
(PCMCIA) card, is a special
expansion card type designed
primarily to accommodate the
needs of the portable computer
market.
There are three types of PCMCIA
slots and cards:
1. Type I cards are 3.3mm thick and
used as memory expansion units
2. Type II cards are 5mm thick and are
used for any expansion device
except hard drives.
3. Type III cards are 10.5mm thick and
designed to be used solely for hard
drives.
Portable Computer Displays
• Notebook and laptop computers
use non-CRT type displays, also
referred to as flat panel displays.
• Two examples of such displays
are Liquid Crystal Display (LCD)
and gas-plasma panels.
– They are much lighter and more
compact than CRT monitors.
– They require much less
electrical energy to operate.
– Both types of display units can
be operated from batteries
Docking Station/Port Replicator
• A docking station is a
device that can be used to
allow a portable PC to use
the normal hardware
devices associated with
desktop computers.
Docking Station
Port Replicator
• A port replicator is similar to
a docking station. It
connects multiple
peripherals to a notebook
but it does not contain any
slots for expansion,
speakers or peripherals.
Upgrading and Troubleshooting
Laptop Computers
• Use the system tools on a
regular basis to keep the
system running smoothly.
• Overheating can cause the
system to slow down and
malfunction.
• Keeping the notebook cooler
can be as simple as raising the
notebook slightly to allow air to
circulate under the computer.
• Notebook cooler pads can be
purchased that utilize fans
powered by the USB port help
keep the notebook cool.
Infrared Device
• Infrared technology, also
known as Infrared Radiation
(IR) is used for wireless
transmission between
computer devices and in
remote controls for
television and stereo
systems.
• To successfully link two
devices, there must be a
transmitter and receiver
with an unobstructed line of
sight between the devices.
Wireless Access Points
• Radio signals are used in
wireless networking
technologies to enable
computers to broadcast
their information to one
another using.
• A wireless access point is
utilized so that computers
in a client/server network
communicate.