Author Topic: A+ Essentials Cram Notes 220-801  (Read 11920 times)

Offline Vijayb

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Re: A+ Essentials Cram Notes 220-801
« Reply #15 on: April 07, 2014, 01:35:02 AM »
Bits and Bytes:

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

The Slot 1 package replaces the Socket 7 and Socket 8 used by previous Pentium processors. Slot 1 is a 242-contact daughter card slot that accepts a microprocessor packaged as a Single Edge contact (SEC) cartridge. A motherboard can have one or two Slot 1s. More recently, Slot 2 package has been developed and used by recent processors.

Offline Vijayb

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Re: A+ Essentials Cram Notes 220-801
« Reply #16 on: April 07, 2014, 01:36:12 AM »
FAT file system:

Under FAT file system, the maximum size of a cluster is 32 KB and the maximum number of clusters
is 65536. Therefore, the maximum size of a partitions is the number of clusters multiplied by the max
size of the cluster, which is equivalent to 2 GB. Remember that 1 KB = 1024 bytes.
New Technology File System (NTFS) is a file system that was introduced by Microsoft to provide
superior features like encryption, compression, and user permissions. NTFS is the primary file system
used in Microsoft's Windows NT, Windows 2000, Windows XP, Windows 2003, Windows Vista, and
Windows 7 operating systems.

Offline Vijayb

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Re: A+ Essentials Cram Notes 220-801
« Reply #17 on: April 07, 2014, 01:37:41 AM »
5. Keyboard

Key board connectors:

Key boards come with two types of connectors. They are:

1. DIN-5, DIN-5 has 5 pins and used with AT style keyboards.
2. Mini DIN-6, also known as PS/2 connector, has around port with 6 pins, one of which being a
square pin used for alignment.

Offline Vijayb

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Re: A+ Essentials Cram Notes 220-801
« Reply #18 on: April 07, 2014, 02:00:56 AM »
6. Power Supply

DC voltages commonly found in a PC:

· +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

One good way of determining a bad power supply is that the fan will not rotate. Also, the computer
will not boot and the LED s indicating the power and disk activity will be OFF.

ATX12V 2.0 power supply provides four different voltages:

3.3Volts, 5Volts, 12Volts and -12Volts. Previous versions of ATX12V used to provide -5V, and it has
been discontinued in version 2.x.

Uninterrupted Power Supply (UPS):

An UPS is required 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.

Offline Vijayb

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Re: A+ Essentials Cram Notes 220-801
« Reply #19 on: April 07, 2014, 02:04:07 AM »
7. Printers and cables:

Laser printers:

The following are the 6 steps in the ElectroPhotographic (EP) print process of Laser Printer:

1. Cleaning: Cleaning the photosensitive drum includes residual toner left on the drum and removing the electrical charges left out on the drum. The physical cleaning is done with a rubber blade and the electrical charge cleaning is done with erasure lamps.

2. Charging: The next step in printing, is to charge the photo sensitive drum with high negative charge, this is done with the help of a corona wire.

3. Writing: A laser (type 3) sweeps the entire length of the drum, creating the static image of the matter to be printed. The places where the laser travel, the highly charges are neutralized. Other places of the drum, it remains highly negatively charged.

4. Developing: Now drum gets in close proximity to the toner. Because the toner is negatively charged, it gets attracted to the areas where the drum is neutral. It will not be attracted to the places where the drum is highly negatively charged. Thus the image of the page to be printed formed on the photosensitive drum.

5. Transferring: Now, the toner on the drum gets attracted toward the paper, by using highly positive charges developed on the surface of the paper. The "transfer corona" is used to generate highly positive charge on the paper surface and to attract the toner from the drum. Thus the image of the page to be printed formed on the paper. But still, the toner is loose and can get easily smeared.

6. Fusing: In order to permanently bond the toner particles to the paper, the paper is passed through rollers. One of the rollers, the non stick roller is heated by a high intensity lamp, generating the heat necessary to bond the toner to the surface of the paper.

Offline Vijayb

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Re: A+ Essentials Cram Notes 220-801
« Reply #20 on: April 07, 2014, 02:06:13 AM »
Problems associated with laser printers and probable causes:

1. Speckled pages: The causes for this may be
         a. The failure to clean the drum after printing properly, or
         b. The drum might have developed scratches.

2. Blank pages: The causes for white pages may be,
         A. The toner would have dried out, replace the toner.
         B. The transfer corona, that is responsible for transferring the toner to the drum might have
                    failed.
         C. The High Voltage Power Supply (HVPS) failure will also result in white pages.

3. Ghosted Images: Ghosting occurs when previously printed pages are printed again, though much
lighter than the present image. The most likely cause is that the erasure lamp might not be working
properly, thus leaving some charges representing the earlier image left on the photosensitive drum
before new image is written. Also check the cleaning blade, which is responsible for scaping the
residual toner.

4. Smudged images: If the fusing fails, the toner will not bond with the paper. Check the halogen lamp responsible for heating.


Offline Vijayb

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Re: A+ Essentials Cram Notes 220-801
« Reply #21 on: April 07, 2014, 02:09:17 AM »
Impact printers are capable of printing multipart forms, since they can give necessary impact to print to multiple forms simultaneously.

ECP (Extended Capability Port) has less control overhead and best suited for transferring large chunks of data, such as between the computer and laser printer.

InkJet Printers is the generic name given for contactless printing using ink. Friction feed is most
commonly used with laser printers, and Inkjet printers.

Printer parallel ports come in the following varieties:

1. Unidirectional: Here, the data travels only from the computer to the peripheral (printer) device.
2. Bi-directional: Here, the data travels both from the computer to the peripheral device and viceversa.
3. ECP (Extended Capability Port): ECP mode offers bi-directional data transfer, as well as DMA for
data transfer.
4. EPP (Enhanced Parallel Port): In addition to bi-directional features, it offers an extended control
code set.

The port that a printer is using can be found by going to Control Panel -> Printers and right click on
appropriate printer. Choose Ports tab to view the port (like COM1, COM2, USB001, etc.) that the
printer is using.

Offline Vijayb

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Re: A+ Essentials Cram Notes 220-801
« Reply #22 on: April 07, 2014, 02:10:44 AM »
Cable lengths:

· Serial cable maximum length is 50 feet.
· Parallel cable maximum length is 10 feet.
· Longer cable lengths may lead to some errors & garbage characters.

RJ – cables:

1. RJ-11: These connectors are used to link modem / phone to the phone line. They have only two pins that get into the modem.
2. RJ-14: RJ-14 connectors are dual-line phone jacks that can accommodate up to 2 telephone line.
3. RJ-45: RJ-45 cable is widely used for attaching UTP cable in LAN environment. These connectors
have eight pins.

The widely used interface cables have the following pin count:

1. floppy-34 pin,
2. IDE-40 pin,
3. SCSI-50 pin,
4. SCSI Ultra wide-68 pin

Ultra IDE cable has 80 wires, and handles better speeds compared to IDE cable with 40 wires. The
additional wires are introduced to reduce noise and thereby improving speed.

Thin co-axial and thick co-axial cables have conductive grounding sheath surrounding the center
conductor. Therefore, the electromagnetic interference (EMI) is significantly less.

Offline Vijayb

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Re: A+ Essentials Cram Notes 220-801
« Reply #23 on: April 07, 2014, 02:12:29 AM »
Cat 6 cabling is recommended for Gigabit Ethernet networking.

Centronics cable, used for parallel printing will have a male DB-25 connector at one end and a
female 36 pin connector at the other end.

When communicating across a serial cable, the most probable cause that the screen is dumping garbled characters is that the communication settings are not correct. Check the speed, parity, start/stop bits etc. If this is all correct, then you need to check the cable. Check whether you need a straight / cross cable, and the pin connections.

Offline Vijayb

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Re: A+ Essentials Cram Notes 220-801
« Reply #24 on: April 07, 2014, 02:14:43 AM »
8. Networking:

Most commonly used network devices are hubs, switches (or bridges), and routers.

Router: 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.

Hub: A hub is basically a multi-port repeater. When it receives a packet, it repeats that packet out each port. This means that all computers that are connected to the hub receive the packet whether it is intended for them or not. It's then up to the computer to ignore the packet if it's not addressed to it. This might not seem like a big deal, but imagine transferring a 50 MB file across a hub. Every computer connected to the hub gets sent that entire file (in essence) and has to ignore it.

Bridge: A bridge is a kind of repeater, but it has some intelligence. It learns the layer 2 (MAC)
addresses of devices connected to it. This means that the bridge is smart enough to know when to
forward packets across to the segments that it connects. Bridges can be used to reduce the size of a collision domain or to connect networks of differing media/topologies, such as connecting an Ethernet network to a Token Ring network.

Offline Vijayb

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Re: A+ Essentials Cram Notes 220-801
« Reply #25 on: April 07, 2014, 02:16:30 AM »
Switch: A switch is essentially a multi-port bridge. The switch learns the MAC addresses of each
computer connected to each of its ports. So, when a switch receives a packet, it only forwards the
packet out the port that is connected to the destination MAC address. Remember that a hub sends the packet out every port, and you can see how much more efficient this it.

Ethernet:

- 10BaseT Ethernet complies to IEEE standard 802.3 and requires an RJ-45 connector to connect to
the NIC. The maximum specified transmission speed for 10BaseT Ethernet is 10Mbps. For 100BaseT,
it is 100Mbps.
- 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 operates at 5 GHz, and is not compatible. Bluetooth is entirely a different protocol standard
- Ethernet is based on CSMA/CD, which stands for Carrier Sense Multiple Access / Collision Detect.
- CAT3, CAT4 or, CAT5 cabling is used with 10BaseT Ethernet. Thin coax is used with 10Base2
Ethernet. Thick coax is used with 10Base5 Ethernet. FDDI uses Optic Fiber as the medium.
- 10Base2 network, also known as Thin-net, uses BNC connector to connect to the NIC.
- A repeater can extend the distance over which the signal can travel without loosing out due to
attenuation.
- The maximum length of the cable for 10BaseT Ethernet segment is 100 meters.
- Thin co-axial and thick co-axial cables have conductive grounding sheath surrounding the center
conductor. Therefore, the electromagnetic interference (EMI) is significantly less.

Offline Vijayb

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Re: A+ Essentials Cram Notes 220-801
« Reply #26 on: April 07, 2014, 02:33:49 AM »
Token Ring supports 4 Mbps and 16 Mbps speeds.

IRQs, and IRQ/ IO conflicts

IRQ                                 Standard Device Assignment                                           I/O Port Address

0                                        System timer                                                                       40Hex
1                                        Keyboard                                                                             60Hex
2                                       Cascade to IRQ9. Can't be used.
3                                       COM ports 2 and 4                                                              COM4:2E8-2EF
                                                                                                                                    COM2:2F8-2FF
4                                       COM ports 1 and 3                                                              COM3:3E8-3EF
                                                                                                                                    COM1:3F8-3FF
5                                    Parallel Port LPT2. Very often
                                      used for sound cards.                                                            LPT2:278-27F
6                                    Floppy drive controller                                                             3F0-3F7
7                                    Parallel Port, LPT1                                                                 LPT1:378-37F
8                                    Real time clock                                                                          70Hex
9                                    Unassigned (Also redirected from IRQ2)
10                                   Available
11                                  Available. SCSI adapter will normally use
                                       this IRQ.
12                                   Available
13                                  Math co-processor.                                                                     F0Hex
14                                 Primary hard-drive IDE controller                                    Primary Hard Drive
                                                                                                                                  170-0177
15                                Secondary hard-drive IDE controller.                              Secondary Hard Drive
                                                                                                                          Controller: 0170-0177
                                                   
                                     Monochrome Graphic Adapter                                               3B0-3BF
                                     Color Graphic Adapter                                                           3D0-3DF

Offline Vijayb

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Re: A+ Essentials Cram Notes 220-801
« Reply #27 on: April 07, 2014, 02:39:40 AM »
To determine the COM port assignments, or which COM ports are being used for what, you can use
any of the following commands:

1. MODE command
2. DEBUG command
3. MSD
4. Corresponding device applet in the control panel

AT Computer interrupt controllers:

An AT computer will have two interrupt controllers. The second interrupt controller need to deliver the interrupts through the primary interrupt controller. IRQ2 had been identified for this purpose on the primary and IRQ9 on the secondary interrupt controllers. In other words, IRQ2 and IRQ9 are
cascaded.

Offline Vijayb

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Re: A+ Essentials Cram Notes 220-801
« Reply #28 on: April 07, 2014, 02:43:37 AM »
Serial Interfaces:

COM1, COM2 on a computer uses serial cable. The pin assignments are shown below. The computer
acts as a DTE (Data Terminal Equipment) and the Modem acts as DCE (Data Communication
Equipment).

Signal                                                        Name                                                    DB9 Pin

RX                                                            Received Data                                                2
TX                                                            Transmitted Data                                            3
DTR                                                          Data Terminal Ready                                      4
GND                                                         Ground                                                           5
DSR                                                          Data Set Ready                                              6
RTS                                                          Request to Send                                            7
CTS                                                          Clear to send                                                 8

Normally, a DTE device connects to a DCE device. If you want to connect two DTR devices, as you
would do to hook up two computers via the serial line to exchange files, the cable itself must have
cross connections. Such a cable is called null modem cable.

Offline Vijayb

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Re: A+ Essentials Cram Notes 220-801
« Reply #29 on: April 07, 2014, 02:45:48 AM »
Most commonly used modem commands:

· ATA- Answer the phone
· ATD-Dial the phone, ATDT for Tone dialing, ATDP for Pulse dialing
· ATH-Hang up
· ATZ-Reset
· AT&F-Reset modem parameters and settings to factory defaults
· AT&W- Write the current parameter values and settings

On a Vista computer, when you connect for the first time to a network, you need to choose a network location. There are two network locations: Home/Work, and Public place. If the computer is shared within home office or small work place, Home/Work option is recommended. If your computer is in a public place or a large network, Public option is recommended.

If your computer is part of a domain, you won't be able to change the network location type because it is controlled by your network administrator.

Network location may be changed as below:

1.Log on to the network.
2.Open Network and Sharing Center by clicking the Start button Picture of the Start button, clicking
Control Panel, clicking Network and Internet, and then clicking Network and Sharing Center.
3.Click Customize, and then click either Public (for "Public place" networks) or Private (for "Home"
or "Work" networks). Administrator permission required If you are prompted for an administrator
password or confirmation, type the password or provide confirmation.
Exam Simulator Security+ Exam Simulator Server+ Exam Simulator
4.Click Next and then click Close.