Digital Environment - Tiddy Flashcards
Hardware:
Physical components/parts. Also things you can physically touch
The instruction cycle:
Cycle a computer system follows
Input device :
A physical piece of hardware that you connect to a computer e.g mice
Output Device:
A piece of hardware which displays out the result of the input once it has been processed
Abstraction:
Ignoring irrelevant information that is not needed
North bridge:
One of the two chips located in the direction towards North in the motherboard. The main function of Northbridge is to manage the communications between the CPU and parts of motherboard.
South Bridge :
South bridge is the another chip of the logical chipset architecture. It is located to the South of (PCI) bus in the motherboard. The main function of South bridge is to control the Input/Output functioning. The North bridge is the medium that connects South bridge and CPU.
Actuator:
A sensor that spins and vibrates your phones
Abstraction:
Eliminating useless/unnecessary information
Primary (Memory):
This refers to memory areas that the CPU can directly access. E.g. RAM, ROM, Cache.
Secondary (Memory):
Non volatile storage that isn’t directly accessible by the CPU.
4 Types of Computers systems :
Mobile Devices, Smart Devices, Personal Computer, Server
Describe what clock speed is:
The number of cycles your CPU executes per second, measured in GHz
Operating Software
A software that runs the computer, manages how hardware receives and processes data.
Batch OS
Used for banking for example payrolls that the system automatically transfers a set of funds on the day of payday (e.g midnight)
Time Sharing OS
Each task is given time to execute so it all round smoothly - The time given to each process is called a Quantum
Network Operating System
Designed primarily to support workstations, personal computers and in some cases, older terminals that are connected via LAN (Local area network).
NAS
Name
NAS - Network Attached Storage.
Who
Enterprises Field/Region of Offices.
How
Allows users to store their files on a
centralized appliance or a storage array.
Can also keep a backup of files incase the
Local drive gives out.
SAN
Name
SAN - Storage Area Network
How
High speed network that provides block-level network access to storage
SANS may also span multiple sites
Computers connect to the SAN
RAID
Redundant
Array
Inexpensive
Disks
CSMA ( CD )
Carrier
Sense
Multiple
Access
Crash
Detection
An network protocol which operates in a MAC address. It senses whether the shared channel for transmission is busy or not and so diverts transmissions appropriately until the channel is free.
CSMA ( CA )
Carrier
Sense
Multiple
Access
Collision
Avoidance
An protocol for carrier transmission in 802.11 networks, Twas developed in order to minimize the potential of a collision occurring when two or more stations send their signals over a data link layer.
MAC Address
The MAC address is embedded into the device when it is manufactured and the owner cannot change it.
A MAC address is a unique code which is built into the Network Interface Card (NIC)
Layer 1 - Physical
When a networking problem occurs, many networking pros go right to the physical layer to check that all of the cables are properly connected and that the power plug hasn’t been pulled from the router, switch or computer, for example.
Easy: So in a sense basic troubleshooting.
Layer 2 - Data Links
The Data Link Layer provides node-to-node data transfer (between two directly connected nodes), and also handles error correction from the physical layer. Two sublayers exist here as well - the Media Access Control (MAC) layer and the Logical Link Control (LLC) layer.
Easy: Between 2 ports directly connected, it handles errors from the physical Layer 1
Layer 3 - Network (Packets)
Here at the Network Layer is where you’ll find most of the router functionality that most networking professionals care about and love. In its most basic sense, this layer is responsible for packet forwarding, including routing through different routers.
You might know that your Boston computer wants to connect to a server in California, but there are millions of different paths to take. Routers at this layer help do this efficiently.
Easy: This layer forwards packets through routing within different routers; IP address also work in this layer.
Layer 4 - Transport (Segments)
TCP and UDP port numbers work at Layer 4, while IP addresses work at Layer 3, the Network Layer.
Easy: TCP (The Transport Layer) deals with the coordination of the data transfer between end systems and hosts. How much data to send, at what rate, where it goes, etc.
Layer 5 - Session
When two devices, computers or servers need to “speak” with one another, a session needs to be created, and this is done at the Session Layer.
Functions at this layer involve setup, coordination (how long should a system wait for a response, for example) and termination between the applications at each end of the session
Easy: A session is when 2 devices attempt to communicate/speak to each other mainly through data; this makes a session
Layer 6 - Presentation
A good example of this is encryption and decryption of data for secure transmission - this happens at Layer 6.
Layer 7 - Presentation
Web browsers (Google Chrome, Firefox, Safari, etc.) TelNet, and FTP, are examples of communications that rely on Layer 7.
Protocol for NBNS
Computer: Hey, what’s your IP?
User: I’m not sure, can you check?
Computer: Checks computer name through NBNS and converts that computer name to an IP address its linked to
Layer - Application Layer
Protocol for SNTP
User: What is the time?
Computer: Checks system time through SNTP
Computer: Outputs “11:51”
Layer - Application Layer
Protocol for SMTP
User: Sends an email
Computer: Receives the request by the user
Computer: Passes the request to an SMTP email server
Computer: Relays that email to the recipient
Layer - Application Layer
Protocol for DNS
User: Opens google.com
Computer: Converts the URL to Google’s IP address (as this is the only way the computer can comprehend the request
Layer - Application Layer
Error handling - Cyclic Redundancy Check
A cyclic redundancy check (CRC) is an error-detecting code commonly used in digital networks and storage devices to detect accidental changes to digital data.
Describe how a data packet is constructed -
A data packet is structured by 3 main parts - the header, the payload and the trailer.
First the header receives the instructions about the payload which consists information such as the source address, a destination address, protocol, and packet number.
Next is the payload, the payload consists of data that is the actual data information the packet carries to its destination. This is what is delivered/transported (being data).
Then lastly is the trailer, its role is to Generally, a trailer contains a few bits that inform the receiving device that it has gotten to the end of the packet, as well as a Cyclic Redundancy Check (CRC), which enables the computer to determine if all the packets were received completely.
TTL - Time to Live
How long a packet can remain on a network for
Data Encapsulation
When a protocol on the sending host adds data to the packet header, the process is called data encapsulation.
