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Comptia A+ Cram Notes

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Comptia A+ Cram Notes

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Contents

[edit section] About This Page

This page contains a bulleted list of short points that you must know for the exam. Please avoid long explanations and list on only key points. You can make bullet lists with "*".

* First level list object ** Second level list object *** Third level list object * Another first level list object

In general use half the words you would normally use and keep points short.

[edit section] Quick Reference Sheet: Cram Notes

  • OSI Model
    • 7 layers: Application, Presentation, Session, Transport, Network, Data, Physical
    • Remember with: All People Seem To Need Data Processing
or backwards Please Do Not Throw Sausage Pizza Away
  • The Windows 9x/Me Registry consists of two binary files called SYSTEM.DAT and USER.DAT. These two files hold virtually every setting that runs the Windows operating system.
  • Wide SCSI permits up to 16 devices per chain, including the controller. Each device must have a unique ID number within the chain. See the device and/or the device documentation for ID settings. The ends of each SCSI chain must be terminated properly, including the controller if necessary.
  • A couple of the most important concepts in hard drive technology are Cylinders, Heads, Sectors per track, clusters, and LBA (Logical Block Addressing). Cylinders reference consecutive rings of space on the circular drive. Heads are the actual devices on the arms that read the data on the drive. A single Sector can contain at most 512 bytes of data, so the sectors are grouped into Sectors per Track (Cylinder) to make data storage more efficient
  • USB 2.0 has a transfer rate up to 480 Mbps and the cable length is up to 5 Meters.
  • USB 1.1 12 Mbps
  • DMA (Direct Memory Access) is the method where the CPU is relieved of certain data transfer functions by allowing peripherals to directly access the system memory. In a system with DMA there are typically two 8237 chips with 7 DMA channels to move data directly to the memory addresses. Due to certain inherent limitations, the practice of DMA has grown into what is now known as Bus Mastering.
  • The drive letters A: and B: are reserved for the floppy drives. The first floppy gets the letter A: and the second gets the letter B:, if installed. Hard drives are the next priority, start with the letter C:, and can continue to Z: if necessary. CD-ROM drives by default get the next drive letter after the last installed hard drive.
  • Network Operating System architecture can take one of three approaches:
    • Client/Server - typically Novell systems, which have a secure, high quality dedicated server.
    • Peer-to-Peer - classically Windows Workgroups. These networks are limited in number, with security and maintenance issues rising proportionally with the size of the network.
    • Domain Based - typically Windows servers which use Domain Controllers and Active Directory, etc. as server software.
  • NetBEUI - An older IBM network protocol that does not lend itself well to routing.
  • IPX/SPX - Typically associated with Novell Netware.
  • TCP/IP - The most popular, and the default protocol for the Internet
  • Next Heading

[edit section] Remembering IRQs

Here are some tips and tricks to remembering IRQs. Please provide your feedback so the final version can be blogged or linked from Tips section of website. Special thanks to Spy.. I stole some of the initial tips from his post :-)

IRQ 0 System timer........like your watch it's round

IRQ 1 Keyboard............first thing you touch when you sit down

IRQ 2 Cascades to 9

Note : You can remember the first three from the phrase Sue Keeps

Cats , with S, K and C representing System, Keyboard and Cascades.

IRQ 3 Com 2&4.......IRQ 3 ( Odd Number) goes to Com2 and Com4 (even Numbers)

IRQ 4 Com1 & Com3.....IRQ 4 (even number) gos to Com1 and Com3 (odd numbers)

IRQ 5 NIC..like the nickel is 5 cents or LPT2(local printer2)

IRQ 6 Floppy Drive.........6 letters...F is the 6th letter for the alphabet (or 6 letters in the word Floppy)

IRQ 7 LPT1........lucky number 7.....if you are lucky to have a printer (or 7 letters in the word Printer)

IRQ 8 Clock..........8o'clock........time for prime time TV shows start (or 8 looks like hour glass that represents clock)

IRQ 9 Redirects to 2

IRQ 10 Available

IRQ 11 Available

IRQ 12 Mouse (PS2[mouse] and IRQ 12 both end with digit 2)

IRQ 13 Maths CoProcessor (13 is unlucky for sum)

IRQ 14 Primary IDE controller.......it's first

IRQ 15 Secondary IDE controller....it's second


Another way to remember this is the naughty mneumonic: Sam Keeps Colorful Condoms Carefully (and) Lovingly For Patricia. They Caress Almost All Monday Mornings Passionately (and) Sensually.

Lack of better mneumonic is regretted. Your suggestions and comments are welcome.

This maps to:

00 Sam -- System Timer

01 Keeps -- Keyboard

02 Colorful -- Cascades to 9

03 Condoms -- Com 2, 4

04 Carfully -- Com 1, 3

(and)

05 Lovingly -- (LPT2 or NIC)

06 For -- Floppy

07 Patricia -- Printer (LPT1)

08 They -- Time ( Real time clock )

09 Caress -- Cascaded IRQ2

10 Almost -- Available

11 All -- Available

12 Monday -- Mouse

13 Mornings -- Math Coprocesso

14 Passionately -- Primary Controller

(and)

15 Sensually -- Secondary Controller


You may need to know the I/O address for IRQ 3 & 4.

IRQ 3...Com 2 2F8

...........Com 4 2E8


IRQ 4...Com 1 3F8

...........Com 3 3E8


Essentially remember the addresses for COM 1-4 and LPT 1 and 2:

COM1: 3F8

COM2: 2F8

COM3: 3E8

COM4: 2E8

LPT1: 378

LPT2: 278

Need a trick for remembering these? Read This Thread On Tricks For Memorizing COM1-4 & LPT1&2 Addresses

[edit section] Laser Printing Process

Here is one for remembering laser printing process


Clean-Charge-Write-Develop-Transfer-Fuse:

Clean-Cows-Won't-Dance-The-Fandango,

Can-Chris-Write-Down-The-Facts

or

Claire-Carefully-Wrote-Down-The-Facts

or

Cute-Chicks-Were-Down-To-Fuck





[edit section] Printer Table

Types of Printers
Printer Description
Impact Daisy Wheel or Dot Matrix (9 or 24 pins)
Inkjet Spray ink on paper
Laser Write with a laser. Also called Electrographic Printer (EP)

[edit section] IP addressing

Network Type Address Range Normal Mask Comments
Class A 001.x.x.x to 126.x.x.x 255.0.0.0 For very large networks
Class B 128.1.x.x to 191.254.x.x 255.255.0.0 For medium size networks
Class C 192.0.1.x to 223.255.254.x 255.255.255.0 For small networks
Class D 224.x.x.x to 239.255.255.255
Class E 240.x.x.x to 247.255.255.255

[edit section] Registry Hives

The Registry Hives

1. HKEY_CLASSES_ROOT - a collection of settings for file, program, and class associations.

2. HKEY_CURRENT_USER - stores settings for the current logged-in user.

3. HKEY_LOCAL_MACHINE - stores settings for devices and hardware on the computer.

4. HKEY_USERS - stores settings for all the users who have accounts on the machine.

5. HKEY_CURRENT_CONFIG - more detailed settings for the hardware on the computer, as currently loaded.

6. HKEY_DYN_DATA(Not present in Windows 2k or XP) - Registry data stored in RAM to speed up system configuration.

[edit section] Devices

Repeaters -A repeater connects two segments of your network cable. It re times and regenerates the signals to proper amplitudes and sends them to the other segments. When talking about, ethernet topology, you are probably talking about using a hub as a repeater. Repeaters require a small amount of time to regenerate the signal. This can cause a propagation delay which can affect network communication when there are several repeaters in a row. Many network architectures limit the number of repeaters that can be used in a row. Repeaters work only at the physical layer of the OSI network model.


Routers -A router is used to route data packets between two networks. It reads the information in each packet to tell where it is going. If it is destined for an immediate network it has access to, it will strip the outer packet (IP packet for example), readdress the packet to the proper ethernet address, and transmit it on that network. If it is destined for another network and must be sent to another router, it will re-package the outer packet to be received by the next router and send it to the next router. Routing occurs at the network layer of the OSI model.


Bridges -A bridge reads the outermost section of data on the data packet, to tell where the message is going. It reduces the traffic on other network segments, since it does not send all packets. Bridges can be programmed to reject packets from particular networks. Bridging occurs at the data link layer of the OSI model, which means the bridge cannot read IP addresses, but only the outermost hardware address of the packet.

[edit section] Physical

  • 10Base2 - Uses Thinnet coaxial cable. Uses a BNC connector and bus topology requiring a terminator at each end of the cable.
  • 10BaseT - Uses Unshielded twisted pair (UTP) cable. Uses star topology. Shielded twisted pair (STP) is not part of the 10BaseT specification.
  • 100BaseT - Also known as fast ethernet. Uses RJ-45 connectors. Topology is star. Uses CSMA/CD media access. Minimum length between nodes is 2.5 meters.
  • ISA - Industry Standard Architecture internal computer bus. Used when the original 8088 8bit microprocessor based personal computers were produced. (16 bit).
  • PCI - Peripheral Component Interconnect internal computer bus. The popular expansion bus of choice. It is significantly faster than EISA. This is a 32bit bus with plug and play capability from Intel

[edit section] FAT Table

Windows 3.1 works with FAT 16
Windows 95 Build 950 and 950a works with FAT 16
Windows 95 Build 950b and 950c works with FAT 32 and FAT 16
Windows 98 works with FAT 32 and FAT 16
Windows NT 4 works with NTFS and FAT 16
Windows 2000/NT 5 works with NTFS, FAT 32 and FAT 16
9x Systems - Windows 95, Windows 98, Windows ME
NT Systems - Windows NT 4.0, Windows 2000, Windows XP
 

[edit section] Boot Option Hot Keys

Boot Option Hot Keys
Operating System Key Result
Windows 98 (9x) F4 Boot to previous OS
F5 Safe Mode
F6 Safe Mode with Networking
F8 Forces a ScanDisk
Left CTRL Advanced Boot Options
Windows NT F5, F8 Hopeless
Spacebar At correct time, permits 'Last Known Good Configuration'
All others Hopeless; verify per installation
Windows 2000,
Windows XP
F5, F8 Advanced Boot Options

[edit section] HOT KEYS

ALT+TAB Switch between open items
ALT+ENTER View properties for the selected item
CTRL+ESC Display the Start menu
win /b Creates bootlog.txt while booting.

[edit section] Quick Windows & OS FACTS

  • NTFS 5.0 was introduced with Windows 2000, and added encryption, mount points, disk quotas, and dynamic disks.


  • The Windows NT Family does not use these files (IO.SYS, MSDOS.SYS, CONFIG.SYS, COMMAND.COM, or AUTOEXEC.BAT).


  • Things To Know
    • Win NT/2000/XP boot files and their there role in the boot process (NTLDR, BOOT.INI, etc)
    • Also Win 9x IO.SYS, MSDOS.SYS AND WIN.COM files
    • How to access the Device Manager in Win.9x and Win 2000/XP
    • How to install a network printer in Win.9x and Win 2000/XP
    • Dual boot systems and the BOOTSEC.DOS file
    • How to startup in safe mode in Win.9x and Win 2000/XP
    • The ERD disk and how to create one
    • When and how to use ASR process in Win XP
    • TCP/IP, HTTP, HTTPS, HTML, NWLINK, FTP, PING, TRACERT


  • The Windows Registry consists of two binary files called SYSTEM.DAT and USER.DAT. These two files hold virtually every setting that runs the Windows operating system.


  • Wide SCSI permits up to 16 devices per chain, including the controller. Each device must have a unique ID number within the chain. See the device and/or the device documentation for ID settings. The ends of each SCSI chain must be terminated properly, including the controller if necessary.


  • A couple of the most important concepts in hard drive technology are Cylinders, Heads, Sectors per track, clusters, and LBA (Logical Block Addressing). Cylinders reference consecutive rings of space on the circular drive. Heads are the actual devices on the arms that read the data on the drive. A single Sector can contain at most 512 bytes of data, so the sectors are grouped into Sectors per Track (Cylinder) to make data storage more efficient


  • USB 2.0 has a transfer rate up to 480 Mbps and the cable length is up to 5 Meters.


  • DMA (Direct Memory Access) is the method where the CPU is relieved of certain data transfer functions by allowing peripherals to directly access the system memory. In a system with DMA there are typically two 8237 chips with 7 DMA channels to move data directly to the memory addresses. Due to certain inherent limitations, the practice of DMA has grown into what is now known as Bus Mastering.


  • The drive letters A: and B: are reserved for the floppy drives. The first floppy gets the letter A: and the second gets the letter B:, if installed. Hard drives are the next priority, start with the letter C:, and can continue to Z: if necessary. CD-ROM drives by default get the next drive letter after the last installed hard drive.


  • NetBEUI - An older IBM network protocol that does not lend itself well to routing.
  • IPX/SPX - Typically associated with Novell Netware.


  • TCP/IP - The most popular, and the default protocol for the Internet


  • Network Operating System architecture can take one of three approaches:
    • Client/Server - typically Novell systems, which have a secure, high quality dedicated server.
    • Peer-to-Peer - classically Windows Workgroups. These networks are limited in number, with security and maintenance issues rising proportionally with the size of the network.
    • Domain Based - typically Windows servers which use Domain Controllers and Active Directory, etc. as server software.

[edit section] RAM Memory Packages

RAM Memory Packages
Package Extension Features
SIPP Single Inline Pin Package Combined 8 DRAM chips on a single card, 8 bits wide
SIMM Single Inline Memory Module Eliminated pins, introduced banking, 30 or 72 pin flavors
DIMM Dual Inline Memory Module 168 pins per stick
RIMM RAMBUS, must be installed in pairs 184 pin form factor

[edit section] RAID

RAID Levels
Level Description Details
RAID0 Striped disk array with no fault tolerance. The several disks operate in parallel for faster data transfer rates.
RAID1 Mirroring and duplexing Creates duplicate copies of data that is split between disks. Mirroring writes from a single controller to two drives. Duplexing uses two separate controllers to write to two different hard drives. Increased access speeds.
RAID2 Data striping w/error recovery Spreads files across several disks; uses large amount of disk space as overhead to maintain parity (error checking.) Not typically used on PCs.
RAID3 Parallel transfer - parity striping Uses less hard drive space for error checking, but data transfer is more time consuming and less efficient.
RAID4 Independent data disks - shared parity disk Interleaves drives to make them appear as one large drive. There is only one parity drive that is shared. Low overhead high maintenance fault tolerance.
RAID5 Independent data disks - distributed parity blocks Popular system where parity is spread across the disks to create accuracy and redundancy.
RAID6 Similar to RAID5 Uses extra disks as well as asynchronous and cached data transmission for guaranteed fault tolerance. Could be called 'Super Raid5'.

[edit section] Types of Expansion Slots

Types of Expansion Slots
Slot Bus Size Notes
ISA
(Industry Standard Architecture)
8 or 16-bit Slowest slot used today
MCA
(Micro-Channel Architecture)
16 or 32-bit Expensive, fast, dead technology
Enhanced ISA 32-bit Compatible with ISA Slots
VL-Bus
(VESA Local Bus)
32-bit Bus Mastering, uses ISA slots with special connectors
PCI
(Peripheral Component Interconnect)
32-bit Bus Mastering, uses PCI slots, has a unique additional bus
PCI-2 64-bit Bus Mastering, uses PCI slots, has a unique additional bus


[edit section] Official ProProfs Network+ Cram Sheet

Official ProProfs Network+ Cram Sheet

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