Computing revision

Computing revision

1. System Architecture

   • Clock Speed
     • Clock Speed is where a CPU carries instructions for the CPU to process. Higher clock speed means that more instructions per second the CPU can carry.
   • Cache Size
     • Cache is a type of memory that is stored in the CPU. This means that it will be faster for the cache to send information to the CPU and then for the CPU to send it back. The cache stores the most frequently opened aplications so that when you open that app it will faster that the other programs.
   • Number of cores
     • Number of cores is how many times the CPU can do the Fetch-Decode-Execute Cycle. This means that if you have more cores it means that the CPU can carry out more instructions at a time.
   • ALU(Von Neumann)
     • ALU is The Arithmetic and Logic Unit. This is where the processor performs arithmetic and logic operations.
   • Embedded Systems
     • These are computers used in car engines . They are dedicated for one purpose.

2. Memory

   • Differences between RAM and ROM
     • One difference between RAM and ROM is that the ROM stores the startup instructions for the computer. The RAM has also a higher capacity than the ROM because it is volatile and the ROM is non-volatile.
   • Purpose of RAM
     • RAM is Random Access Memory. This means that it is a volatile memory. This means that when the computer is shut down all the data will be lost. RAM is used to store information that it needs for the CPU to make.
   • Purpose ROM
     • ROM is Read Only Memory. This is a non-volatile memory. This means that the data will not be deleted. ROM stores the start up instructions for the computer.
   • Virtual Memory - Why?
     • Virtual memory is the process where the RAM is full and it uses the Hard Drive as extra memory. This means that the computer will be slower because it will take longer for the instructions to travel to the Hard Drive and then back to the CPU.
   • Flash Memory
     • Flash Memory is a hard drive that doesn't have any moving parts. So this means that it is faster that Hard Disk because it has no moving parts. This also means that it is a non-volatile memory. This is usually used in SSDs, micro sd cards, memory sticks, etc.

3. Storage

   • Secondary - Why?
     • Secondary storage is a type of device that can store data. This is non-volatile so it means that data can be saved even if the computer is turned off. It also is used in most of the computers now a days.
   • Optical
     • Optical storage is where data can be edited readed or transferred using light. This is usually used by CD readers.
   • Magnetic
     • Magnetic Storage involves discs spinning and magnets which can store data. This is a non-volatile data because it can be stored when the computer is closed.
   • Solid State
     • Solid State is a device where it involves no moving parts. So this means that it faster that the other storage options. This is non-volatile which means that all the data is saved when you shut down a computer.
   • Key differences

4. Wired and Wireless Networks

   • LAN vs WAN
     • LAN network is where there are a bunch of computers are connected together. This means that they will not have access to the internet. A LAN network usually covers small buildings e.g. Colleges, Offices, etc.
     • WAN is Wide Area Network. This means that there are multiple computers connected to eachother in different locations. So this means that the computers need a server so that they can communicate with eachother. This requires servers and ports which are expensive.
   • Client Server vs Peer to Peer
     • Client Server is the relationship between the browser and the server. So this means that the server will need to give a key to the client so that it can access the website or the server.
     • Peer to Pear is where each computer acts like a server. So this means that the users data can be easily modified and shared with others. It also means that it doesn't require a server.

5. Network Topologies

   • Ring, Star and Bus
     • The Bus network is where a bunch of computers and printers are connected to a server through only one cable. This means that if something wrong happens with the cable it means that the users will not be able to access the data from the server anymore.
     • The ring network is connected to two other devices. The data needs to go round through other computers so that the data can go to the server or the printer. This means that the data will be lost if the cable fails.
     • Star network. This is where each computer has a cable to the server. This means that if the one of the cable fails the other people will be able to access the server.
   • IP Addresses
     • The IP address is a bunch of numbers which are broken into 4 8 bit numbers. This is used by every single device.
   • Layers
   • Packet Switiching
   • Protocols
     • Protocols are a bunch of rules which the internet has.

6. System Security

   • Malware
     • This is a software designed to manipulate computers and breach data without people knowing.
   • Phising
   • Brute Force Attacks
   • Data Interception Theft
   • Firewall
   • Passwords
   • Encyption