Transcript
CompTIA A+: 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 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. A cluster is the smallest storage unit of data and consists of 2 or more sectors based on the file system. 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. 1
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
Resources to Memorize COM1: 03F8 - IRQ 4 COM2: 02F8 - IRQ 3 COM3: 03E8 - IRQ 4 COM4: 02E8 - IRQ 3 LPT1: 378 - IRQ 7 LPT2: 278 - IRQ 5
Electro Photographic Print Process: Clean-Charge-Write-Develop-Transfer-Fuse California -Clean-Cows-Won't-Dance-The-Fandango
Types of Printers Impact - Daisy Wheel or Dot Matrix (9 or 24 pins) Inkjet - Spray ink on paper Laser - Write with a laser. Also called Electro Photographic Print Process (EP)
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IP addressing Network Type Address Range Class A
Normal Mask
Comments
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
Multicasting
240.x.x.x to 247.255.255.255
Experimental
TCP/IP Cheat Sheet 128 128
192 64
224 32
240 16
248 8
252 4
254 2
255 1
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. 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.
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Devices Hubs – Connects multiple computers together with no intelligence. All packets are forwarded to every port. Operates at the OSI level 1 Physical Layer. Switch - Connects multiple computers together with some intelligence. All packets are inspected to read the MAC address to determine which port of the switch to allow the packet to pass to. Enables multiple communications at the same time through the switch. Operates at the OSI level 2 Data Link Layer. Repeaters -A repeater connects two segments of your network cable. It regenerates the signals to proper amplitudes and sends them to the other segments. Operates at the OSI level 1 Physical Layer. Routers -A router is used to route data packets between two networks, connecting LANs. 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 –Filters based on the MAC address. 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.
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 4
TCP/IP, HTTP, HTTPS, HTML, NWLINK, FTP, PING, TRACERT
Network 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.
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
68 pins per stick
RIMM
RAMBUS, must be installed in pairs
184 pin form factor
SODIMM
Small Outline DIMM
used in laptops and mobile devices
RAID Levels Level Description Details RAID 0 - Striped disk array with no fault tolerance. The several disks operate in parallel for faster data transfer rates. RAID 1 - 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. RAID 5 - Striped with Parity. Independent data disks - distributed parity blocks Popular system where parity is spread across the disks to create accuracy and redundancy.
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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
PCIe (PCI Express)
Mastering has a unique additional bus
64-bit Bus
Backup Types Type Normal (Full) Incremental Differential Copy Daily
Looks for Archive bit NO YES YES NO NO
Turns off Archive bit after backup YES YES NO NO NO
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