CompTIA®
A+ Certification
A+ Core (220-301) Hardware Technologies
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A+
Certification, awarded by CompTIA® organization is the most widely recognized
certification in the area of PC hardware and software
technologies. To attain A+ certification, one need to
pass 2 exams, namely, A+ Core Hardware Technologies, and
A+ Operating Systems Technologies. These exams basically
test the skills in assembling a computer,
troubleshooting, and the ability to work with various
operating systems. Linux is not included in the A+
Certification Operating Systems exam, as it has an exam
of its own (Linux+ Certification), offered by CompTIA.
The exam cram offers several final preparation points
for candidates intending to appear for the A+ test.
Latest objectives are available from Comptia.com
website.
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11. 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.
12. It is important to know
IRQs, and IRQ/ IO conflicts.
|
IRQ
|
Standard
Device Assignment
|
I/O
Port Address
|
|
0
|
System
timer
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40Hex
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1
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Keyboard
|
60Hex
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2
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Cascade
to IRQ9. Can't be used.
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3
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COM
ports 2 and 4
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COM4:
2E8-2EF
COM2:
2F8-2FF
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4
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COM
ports 1 and 3
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COM3:
3E8-3EF
COM1: 3F8-3FF
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5
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Parallel
Port LPT2. Very often used for sound cards.
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LPT2: 278-27F
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6
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Floppy
drive controller
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3F0-3F7
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7
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Parallel
Port, LPT1
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LPT1: 378-37F
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8
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Real
time clock
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70Hex
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9
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Unassigned
(Also redirected from IRQ2)
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10
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Available
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11
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Available.
SCSI adapter will usually use this IRQ.
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12
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Available
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13
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Math co-processor.
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F0Hex
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14
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Primary hard-drive
IDE controller
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Primary Hard Drive
Controller: 1F0-1FF
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15
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Secondary hard-drive
IDE controller.
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Secondary Hard Drive
Controller: 0170-0177
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Monochrome Graphic
Adapter
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3B0-3BF
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Color Graphic Adapter
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3D0-3DF
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-
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
13. 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
otherwords, IRQ2 and IRQ9 are cascaded.
14. 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).
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Signal
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Name
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DB9
Pin
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RX
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Received
Data
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2
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TX
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Transmitted
Data
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3
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DTR
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Data
Terminal Ready
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4
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GND
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Ground
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5
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DSR
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Data
Set Ready
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6
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RTS
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Request
to Send
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7
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CTS
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Clear
to send
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8
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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.
15. 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.
16. SCSI Types:
|
SCSI
Type
|
Transfer
speed
|
bus
|
|
SCSI-1
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5MBPS
|
8
bit bus
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Fast
Wide SCSI
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20MBPS
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16
bit bus
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Wide
Ultra SCSI
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40MBPS
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16
bit bus
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Ultra2
SCSI
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40MBPS
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8
bit bus
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Wide
Ultra2 SCSI
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80MBPS
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16
bit bus
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Ultra3
SCSI or Ultra 160
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160MBPS
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16
bit bus
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Ultra320
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320
MBPS
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16
bit bus
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SCSI ID - 0=bootable drive,
7=controller, 1-6=any other devices
Wide-Ultra SCSI - 16
devices, 0=bootable drive, 15=controller
17. Each device in a SCSI
chain need to have unique ID. For a 16-bit Wide SCSI,
there are 16 possible SCSI Ids, 0-15. A standard 8-bit
SCSI can support only 8 devices (including SCSI card),
the Ids allowed are 0-7.
18. SCSI bus termination:
If
the termination is not done, a SCSI devices on the bus
will not function properly. This is due to reflection of
the signals at the end of the bus. To prevent this, both
ends of the SCSI bus need to be terminated. If one end
of the SCSI bus is terminated, you may find intermittent
problems. Never terminate the bus at a device connected
in between.
19. 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
20. Tools - Screw driver
types:
·
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
