Monitors accumulate very high static charges and
need to be handled very carefully. Before attempting
any repair, it is imperative to discharge any accumulated
charges on the monitor. You can use a jumper, one end
of which is grounded, and touch the other end of the
jumper wire to the anode of the monitor. While doing
so, ensure that you are not in direct contact with the
jumper wire or the anode. You can use a screw driver
or a nose pliers with rubber handle for this purpose.
A "POP" sound can be heard when the static charges accumulated
on the anode lead getting grounded through the jumper
wire. Remember, that if you get in contact with the
static charge, it may lead to severe burns or even fatal
accident!
Never wear a wrist strap when working on monitors.
Monitors contain very high voltages, sometimes fatal
to human, even when the power is turned off. If you
are wearing wrist strap, the human body work as a conduit
to discharge the electric charge.
The following devices require periodic cleaning:
1. Floppy drives
2. Tape drives
3. Printers
4. Mouse
User level security gives better control of resource
on user to user basis. Share level security assigns
passwords to the resources rather than the users and
less secure.
3)When signals are transmitted over a long distance,
there will be ohmic losses, which result in loosing
the strength of the signals. This is known as attenuation.
Amplification is opposite of attenuation.
4)While preparing for dual boot with Windows 2000
Professional, note the following points:
1. Windows 2000 must be installed on a separate volume.
If a separate volume is not available, repartition the
hard disk suitably, and reformat. You also need to take
suitable backup.
2. If you want to have dual boot between Windows
NT 4 and Windows 2000 as the only operating systems,
ensure that Service Pack 4 is installed on Windows NT
4. This is required since Windows 2000 upgrades the
NTFS to NTFS 5. NT4 requires Service Pack 4 to read
and write to NTFS 5.
3. You must install Windows 2000 only after installing
MS-DOS or Windows 95.
.COM, .EXE, .BAT files are executable files.
+5 and +12 volts are the DC voltages commonly found
on PCs
80386/486 operate at +5v
Pentium and above operate at +3.3v
Power supply wires - yellow=+12v, blue=-12v, red=+5v,
& white=-5v
1 KB = 1024 bytes
1 MB = (1024 X 1024) bytes
= (1024X 1 KB) bytes
= 1,048,576 bytes
1 GB =
(1024 X 1024 X 1024 )bytes
= (1024 X 1 MB) bytes
= (1024 X 1024 X 1 KB) bytes
= 1,073,741,824 bytes
KB stands for Kilobyte
MB stands for Megabyte
GB stands for Gigabyte
Byte is represented by "B"
as in MB
Bit is represented by "b" as in
kbps
One byte is 8 bits
5)Computer viruses:
1. A boot sector virus stays resident by infecting
the boot sector of the computer
2. A Master boot record (MBR) virus infect the first
physical sector of all affected disks
3. File viruses either replace or attach themselves
to executable files, is the most commonly found virus.
4. Macro virus attaches itself to documents in the
form of macros.
5. Memory viruses are viruses that execute and stay
resident in memory. Trojan Horse is an example of memory
virus.
10BaseT Ethernet complies with IEEE standard 802.3
and requires an RJ-45 connector to connect to the NIC.
10Base2 network, also known as Thin-net, uses BNC
connector to connect to the NIC.
A 10BaseT cable can extend up to 100 meters without
the use of a repeater
10Base2 network uses thin coaxial cable and need
to be terminated with a 50 ohm termination at both the
ends.
6)144-pin small outline DIMM (SO DIMM) is commonly
used in notebook computers. 144-pin micro-DIMM is still
smaller than the so-DIMM and used in sub-notebook computers.
72-pin SODIMM was used in older laptops.
256MB PCI Express is recommended for computers that
use high-end video applications.
802.11b operates at 2.4 GHz, while 802.11a operates
at 5 GHz. Typical data rate for 802.11b is 11 Mbps where
as it is 54mbps for 802.11a.
802.11b is compatible with 802.11g. 802.11a is not
compatible with 802.11b or 802.11g. Bluetooth is entirely
a different protocol standard, and is not compatible
with any of the 802.11 standards.
A CD can be recovered from any minor scratches by
using polishing chemicals. But it does not guarantee
repair. Only way to safeguard is to make a back-up copy
of the CD.
7)A computer may reboot because the CPU is overheating.
Ensure that you have sufficient ventilation for proper
airflow, and that the CPU fan is working.
A connection device that is plugged into a computer's
serial/parallel port in order to perform a loopback
test is known as a loopback adapter.
A Flat blade screw driver has Minus slot
A Philips screw driver has X shape slot
A Torx screw driver has star tip or head
A Hex screw driver has hex head
A good fuse will show close to zero ohms ( typically
less than 1 ohm). A bad fuse, will have open contact,
and will show open
A hard disk should never be low level formatted at
the customer premises. It is highly recommended that
it is done at the manufacturer's or at any authorized
center.
It is very cumbersome to change the partition sizes,
once the hard disk is partitioned and used. It may require
backing up all the data and restoring after repartitioning.
8)A work station/PC very commonly connects to a LAN
by means of an RJ-45 connector on a LAN card (Also known
as NIC, or Network Interface Card).
A hub is used as a concentration point for connecting
together all the segments in a 10BaseT network. Another
network devices that is used extensively for this purpose
is a switch.
NIC (Network Interface Card) resides inside the PC
cabinet.
A repeater is used for joining two or more Ethernet
segments. A repeater can extend the distance over which
the signal can travel without loosing out due to attenuation.
50 Ohm termination is normally used at the ends of
a 10Base2 network to prevent signal reflection at the
ends of the cable.
A Network Interface Card is required to be present
in the PC to communicate over a LAN. A switch or a Hub
may be required or may not be required depending on
the network configuration. For example, if you have
10Base2 (Thinnet) network, you may not need a Hub or
a Switch. Router is required only when there is routing
involved.
9)A router for Internet sharing is normally configured
using web browser. High-end routers may provide option
for terminal connectivity, wherein you can connect a
terminal, and issue commands for configuring the router.
A Secure Digital (SD) card is a small memory card
used to make storage portable among various devices,
such as cellular phones, PDAs, digital cameras, music
players, and personal computers. It uses flash memory
to provide nonvolatile storage, which means that a power
source is not required to retain stored data.
A SIMM has a single row of 72 contact fingers, each
making contact on both sides. An older version of SIMM
card contain 30pins, and were used in 386 and 486 machines.
A DIMM (Dual-Inline Memory Module) has two rows of
connecting fingers, one row on each side, and the total
number of contacts are 168.
10)A. SCANDISK: ScanDisk is a utility program that
was added to DOS Version 6.0. SCANDISK is a better compared
to CHKDSK. SCANDISK can fix errors on data storage devices
such as hard disks, floppy disks, RAM drives etc, and
DoubleSpace compressed drives. It analyzes and repairs
damage to the following:
1. Physical clusters
2. File allocation table
(FAT)
3. Lost clusters
4. Cross-linked files
5. Directory tree
6. MS-DOS Boot sector
7. DBLSPACE
volume header, file structure, compression structure.
B. CHKDSK (Check Disk): CHKDSK command, one of DOS
commands, examines your hard drive for error conditions
and reports the total size of the disk, how many files
are stored there, and the space remaining. CHKDSK also
reports the total amount of conventional memory in your
system and the amount of conventional memory available.
Note that CHKDSK can't report extended memory.
C. DFRAG: The DFRAG.EXE is included with DOS6.0 and
later. DEFRAG utility arranges the clusters of data
on the hard drive to achieve better performance by placing
all of the clusters for a given file together in a contiguous
order. DEFRAG does not do any repair on your disk, and
errors, if any will remain on the disk.
D. BACKUP: DOS has a backup utility since version
2.0.
11)Active link LED on a network card is an indication
that the link is up. You will be able to ping the local
host even without the network connectivity. Device Manager
NIC status not necessarily ensures that the network
cable is plugged properly in to the NIC.
Active listening focuses on who you are listening
to, in order to understand what he is saying. As the
listener, you should then be able to repeat in your
own words what they have said effectively. This does
not mean you agree with, but rather understand, what
they are saying.
AMR slot: AMR stands for Audio Modem Riser. AMR is
a riser card that supports sound or modem function.
With increasing CPU computational power, the digital
processing job can be implemented in main chipset and
share CPU power.
CMR slot: CNR stands for Communication Network Riser.
CNR is a riser card specification that supports V.90
analog modem, multi-channel audio, phone-line based
networking, and 10/100 Ethernet based networking. The
digital processing is implemented in main chipset and
share CPU power.
A modem can also be inserted using PCI slot. But,
in such case, it will not be using onboard audio CODEC
or CNR digital controller. The AMR card primarily attends
to conversion of analog signals to digital and visa
versa. Slot I is associated with CPU slots.
An IP address is considered private if the IP number
falls within one of the IP address ranges reserved for
private uses by Internet standards groups. These private
IP address ranges exist:
10.0.0.0 through 10.255.255.255
172.16.0.0 through
172.31.255.255
192.168.0.0 through 192.168.255.255
Private IP addresses are typically used on local networks
including home, school and business LANs including airports
and hotels.
12)An UPS is desired to be purchased for any critical
and un-interrupted use of computers. It has the following
benefits:
1. Provide protection against small surges
2.
Filters noise from entering the computer
3. Provide
power to the computer during line power failure
4.
Give stable power to computer, even when the line power
is unstable.
Note that the UPS can give un-interrupted power only
for a fixed amount of time under a given load, in the
absence of line voltage.
Anti-virus software, and anti spy-ware software can
be used to clear malicious programs from a computer.
Also, note that you need to install up-to-date Service
Packs, and patches.
Anti-virus update files are traditionally called
as "Definitions".
If a PC becomes slow, as a first step, you need to
run Disk Cleanup and Disk Defragmenter. Additionally,
you can consider adding a second hard drive or more
memory.
13)As the humidity decreases, static build up will
increase and vice versa. A level of 50% is considered
safe. Below 50% humidity, static build up will be more.
Asynchronous serial communication uses Start-bit/Data-bits/Stop-bit.
A modem connecting to the Internet is a typical asynchronous
device.
Synchronous communication uses clock signals to transfer
information. Does not use start/stop bits. Synchronous
communication is normally used for high speed data transfers.
Batteries contain environmentally hazardous chemicals
and therefore, should not be disposed through dust bit.
Always refer to the manufacturer's instructions or the
relevant State guidelines. The same is true when you
are disposing chemical solvents.
Automated System Recovery (ARS) requires that a system
backup be taken using Windows XP Backup utility.
14)AT motherboards were discontinued in the mid 1990s.
The AT motherboard can be distinguished by the position
of key board plug and power socket. Also, it has only
a key board connector on board and doesn't support other
ports for mouse or printer. Baby AT is a form of AT
motherboard with reduced dimensions. AT motherboard
is also called Full AT. ATX mother boards have serial
and parallel ports to support printer, mouse and also
USB support is provided. ATX has one rear plate that
enables acess to all necessary ports. Also, ATX uses
one P1 power connector instead of P8 and P9 connectors.
The one shown in the exhibit is an ATX motherboard.
ATX power supply provides three different voltages:
3.3Volts, 5Volts, and 12Volts.
Next
