Computer Science

Computer Science

1. DATA REPRESENTATION

   • Computer storage - measured in multiples of bytes
   • Register - small piece of memory where values can be held
   • Computer don't work with hex, they convert it first
   • Data Compressions reduce size of a file - 1) Lossy 2) Lossless

2. COMMUNICATION & INTERNET TECHNOLOGIES

   • Malware
     • Software program made to damage/disrupt a computer
   • Virus
     • Software program made to corrupt a computer and its files
   • Spyware
     • Software program that collects user's info through internet connection
   • Firewalls & anti-virus software minimise risks
   • Cookies
     • Tiny piece of data downloaded by a computer when it visits a website.
     • Can store details or personalise adverts from surfing history - concerning for user

3. COMPUTER ARCHITECTURE, LANGUAGES & OPERATING SYSTEMS

   • Von Neuman Architecture
     • designed to be easier to program
     • uses buses and registers
   • Control Unit (CU)
     • 'brain' - controls data
   • Buses
     • series of pathways
       • data bus - carries data
       • address bus - carries memory address
       • control bus - carries instructions
   • Compiler
     • takes whole program in high-level language and translates it to machine code
   • Assembly Language
     • low-level programming language that uses mnemonic codes to create programs
   • Inerpreter
     • translates program into machine code line-by-line

4. LOGIC GATES

5. SECURITY

   • Malware
     • cause data loss or unauthorised access to data
     • viruses, worms, Trojan horses & spyware
   • Pharming
     • uses emails to trick user into giving away personal details
   • Phishing
     • directs user to fake websites where they might give away personal data
   • Denial of Server (DoS)
     • attempt to prevent access to data
   • Encryption
     • disguises contents of a message using a key
   • Protocols
     • sets of rules that handle communication between computers

6. FLOWCHARTS

7. DATABASES

   • stored in tables consisting of records and fields
   • Primary Key - field that holds data that uniquely identifies a record
   • a search = a query
   • SQL = programming language used to maintain databases and to create queries.
   • Query by example = common method of searching a database

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