AS Computing Unit 1 Cheat Sheet by Horatio
RAM vs Cache Memory
Fast read and write access
Faster read and write access
Used to store data and currently running programs
Used to store frequently used data
Necessary as most data is stored on slower storage media
Resides close to CPU
Defragmentation of SSDs
SSD uses direct access, so there woudl be no improvement in read times
May perform "trim" command which imrpoves speed of write operations
SSD uses NAND based flash memory. Defragmentation may shorten its lifespan.
FTP vs UDP
Breaks data into packets
Breaks data into packets
Can re-send dropped or damaged packets
Does not re-send dropped or damaged packets
Packets can be re-assembled if they arrive out of order
FTP not useful for streaming media, as receiving new packets is more important than receiving old ones
UDP useful for streaming media, as receiving new packets is more useful than receiving old ones
Floating Point vs Integer
Numbers are stored accurately
Non-integers can be stored
Requires less complex processing
Greater range of numbers can be stored
Allows for exact representation of 0
Takes up less storage space
Von Neumann Architecture
Manages Fetch/Decode/Execute cycle
Processes data involving arithmetic and logical operations
A small/fast/temporary storage addressed by mechanisms other than main memory
Connects all internal components of a computer
Fast, easily accessed memory close to the CPU.
If one cable breaks, network will still operate.
Faults are easy to detect.
Data has to pass through hub, so it is very secure.
Easy to add new stations.
Exchange of signals between devices to establish readiness to communicate
Example: Establishing a printer's readiness to print
Data split into packets
Each packet can be transmitted on different routes
Packets may arrive out of order
More secure than circuit switching
Makes more efficient use of data lines
Contains source address, order number of packet and parity bit.
Fast data transfer
Cost-effective cost per unit of storage
Portable and can be stored securely
Third party storage provider
Fast transfer(depending on network speed)
Could be more expensive than HDD due to company fees
Data is stored securely
Flash memory drive
Very fast access
Cost effective cost per unit of storage
Can have very slow access speed
Allows for very large amounts of storage
Transferring multimedia web pages over the Internet
Assigning dynamic IP addresses to devices on a network.
In one direction only
In both directions, but not simultaneously
In both directions simultaneously
Physical location of a piece of data is calculated using a hashing algorithm
Calculation is carried out on the primary key
Data collision occurs when two items are hashed to the same location
In this case, the data is sent to the overflow area.
When there are many hash collisions, access to the overflow area may be slow
A new hashing algorithm is required and a larger file may be needed.
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