Computer Science Notes PDF

Topic: Write Top green=keyword Key Terms Write notes/Draw Diagrams here Write Key Terms Here… Key People… Key Dates… Main Themes… When you have finished writing your no...

Topic: Write Top green=keyword Key Terms Write notes/Draw Diagrams here Write Key Terms Here… Key People… Key Dates… Main Themes… When you have finished writing your notes, go back through and extract all key terms write them in the Left column… Summary - If you were explaining this area of the Curriculum to someone else, this is what you would tell them... Topic:cpu Write Top Key Terms Write notes/Draw Diagrams here Write Key Terms Here… The control unit coordinates all of the activities on the cpu The alu or arithmetic logic unit is where the actual calculations are done Key People… The fetch decode execute cycle is when the cpu(computer processing unit) fetches an instruction decodes the instruction and then carries out that instruction Key Dates… and repeats The ALU(arithmetic logistical unit) is where the actual calculations are made Main The accumulator is where the results of instructions are stored before transferred Themes… to memory pc(program counter) the program counter holds the address of the next instruction to be executed mar(memory address register) is where the memory address of the current instruction is being hold and then the data it also uses so they can be fetched from memory mdr(memory data register) it holds the actual instruction and then the data that has been fetched from memory 1 megahertz=1 million fetch decode execute cycles  Registers is a very fast memory location on the CPU In exams they may say F-E cycle (it is the same as the fetch decode execute cycle just without saying the decode but the decode still happens ) LDA means load data address MAR looks for the data and the MDR holds the data that the MAR got from the ram RAM (random access memory) the short term memory Plenary: What is the purpose of the CPU? What are two major components of the CPU, and what is the purpose of each?-MAR/MDR What is a register?-a very fast memory location on the CPU  Name four special registers in the CPU When you have finished writing your notes, go back through and extract all key terms write them in the Left column… Summary - If you were explaining this area of the Curriculum to someone else, this is what you would tell them... Topic:Computational Write Top thinking Key Terms Write notes/Draw Diagrams here Write Key Terms Here… A algorithm is a sequence of steps to solve a problem or set or instructions Abstraction taking out the unnecessary parts Key People… Decompation involves breaking down a large problem into subproblems Key Dates… Main Themes… When you have finished writing your notes, go back through and extract all key terms write them in the Left column… Summary - If you were explaining this area of the Curriculum to someone else, this is what you would tell them... Topic:flow charts Write Top Key Terms Write notes/Draw Diagrams here Write Key Terms Here… Key People… Key Dates… Main Themes…  Constructs=sequence,selection,irritation When you have finished writing your notes, go back through and extract all key terms write them in the Left column… Summary - If you were explaining this area of the Curriculum to someone else, this is what you would tell them... Topic:memory Write Top Key Terms Write notes/Draw Diagrams here Write Key Terms Here… Key People… Key Dates… Main Themes… ROM-read only memory RAM-random access memory Anything currently open is opened in RAM(files/websites/games) Docs are not opened in RAM but in chrome and chrome is loaded in RAM not the doc When the computer is turned of the RAM is empty and is volatile Volatile means memory is wiped when there is no power to the component RAM is volatile Hard drive and hard disk are the same things Virtual memory is a section of the hard drive Virtual memory is temporary RAM on the hard drive Things don't run in virtual memory to run something from virtual memory it has to transfer from the harddrive to RAM Lag can be caused from apps needing to load things from virtual memory to RAM then transfer something from RAM to virtual memory to create space in the RAM ROM checks the system such as if the hard drive is spinning or the cpu is to hot or too cold like checking if a car has fuel and wheels or everyone has there seatbelts on  When you have finished writing your notes, go back through and extract all key terms write them in the Left column… Summary - If you were explaining this area of the Curriculum to someone else, this is what you would tell them... Topic:secondary Write Top storage Key Terms Write notes/Draw Diagrams here Write Key Terms Here… Reading from an optical device is slower than reading from a magnetic device whereas reading from the cloud is faster than both Key People… Secondary storage is non volatile Secondary storage is the long term memory Key Dates… Keeps data when turned off Offline secondary storage is something you can take with you such as a xbox Main game Themes… On a test storage medium means storage type USB stands for universal serial device  When you have finished writing your notes, go back through and extract all key terms write them in the Left column… Summary - If you were explaining this area of the Curriculum to someone else, this is what you would tell them... Topic: Write Top review Key Terms Write notes/Draw Diagrams here Write Key Terms Here… REVIEW: Key People… Primary storage Secondary storage RAM-volatile Secondary storage is needed for Key Dates… ROM-read only memory long term storage Virtual memory is used when RAM Data is moved from secondary Main is full storage to RAM to run Themes… Virtual memory is not as fast as RAM(because it has to transfer  from virtual memory to RAM) Virtual memory is NOT THE CLOUD When you have finished writing your notes, go back through and extract all key terms write them in the Left column… Summary - If you were explaining this area of the Curriculum to someone else, this is what you would tell them... Topic: Write Top Intro to binary Key Terms Write notes/Draw Diagrams here Write Key Terms Here… Switches only have 2 options 0 or 1 Everything a computer needs to process needs to be converted into binary Key People… Key Dates… Main Themes… 1GB=1000 mb 4gb=4000mb  Number of bits Possible number of The combernations combinations 1 2 0 or 1 2 4 00 or 01 or 10 or 11 3 8 000 or 001 or 010 or 011 or 100 or 101 or 110 or 111 When you have finished writing your notes, go back through and extract all key terms write them in the Left column… Summary - If you were explaining this area of the Curriculum to someone else, this is what you would tell them... Topic: Write Top data representation Key Terms Write notes/Draw Diagrams here Write Key Terms Here… Key People… During exams always add the 0’s in binary even if they are not necessary always add them you will lose marks Key Dates… Hexadesimal is the first number times 16 add the second number example is 27 is 2x16+7=39 or 43 is 4x16+3=67 Main Themes… When you have finished writing your notes, go back through and extract all key terms write them in the Left column… Summary - If you were explaining this area of the Curriculum to someone else, this is what you would tell them... Topic: Write Top Replit tips Key Terms Write notes/Draw Diagrams here Write Key To get replit to output a number in binary write bin(“the number”) e.g Terms Here… print(bin(245)) To get replit to output a number in hexadecimal write hex(“the number”) e.g Key People… print(hex(423)) Key Dates… MOD is- The remainder is the amount left over after the division is performed. For example, the remainder of the Main division operation 10/3 is 1, since 10 divided by 3 equals 3 Themes… with a remainder of 1. When you have finished writing your notes, go back through and extract all key terms write them in the Left column… Summary - If you were explaining this area of the Curriculum to someone else, this is what you would tell them... Topic: Write Top Binary addition  Key Terms Write notes/Draw Diagrams here Write Key Terms Here… Key People… Key Dates… Main Themes… Overflow error is when there answer should bit in 8 bit but exceeds 128 meaning it needs to be 9 bit binary To multiply you shift the numbers to the left and add 0’s in the place of the removed numbers To divide you shift to the right and any numbers that are lost are not replaced  When you have finished writing your notes, go back through and extract all key terms write them in the Left column… Summary - If you were explaining this area of the Curriculum to someone else, this is what you would tell them... Topic: Write Top Character representation Key Terms Write notes/Draw Diagrams here Write Key Terms Here… ASCII means american standard code for information interchange Key People… Key Dates… Main Themes… When you have finished writing your notes, go back through and extract all key terms write them in the Left column… Summary - If you were explaining this area of the Curriculum to someone else, this is what you would tell them... Topic: Write Top Images on a computer Key Terms Write notes/Draw Diagrams here Write Key Terms Here… A black and white image can be 1 bit 1=white and 0=black A 1 bit image means each pixel = 1 bit Key People… A 12 bit image means each pixels = 12 bits The resolution an image is the number of pixels in a area Key Dates… Main Themes… When you have finished writing your notes, go back through and extract all key terms write them in the Left column… Summary - If you were explaining this area of the Curriculum to someone else, this is what you would tell them... Topic: Write Top How sound is represented Key Terms Write notes/Draw Diagrams here Write Key Analogue sound is continuous Terms Here… Digital signals are discrete Key People… Key Dates… Main Themes… For a computer to understand sounds they need to read it through analogue such as a microphone Sample rate is number of samples per seconds The more samples larger the file size More bits used per sample enables the height of the wave to be more accurately measured but increases file size The number of bits (audio bit depth) used to record each measurement is known as the resolution Lossy compression removes the sounds in the frequency ranges that  we can’t so easily hear or that least affect the perceived playback quality Lossy compression leaves out some data – this can affect the sound quality Lossless compression leaves out repeated data and instead makes a note of how many times it is repeated When you have finished writing your notes, go back through and extract all key terms write them in the Left column… Summary - If you were explaining this area of the Curriculum to someone else, this is what you would tell them... Topic: Write Top Seneca notes Key Terms Write notes/Draw Diagrams here Write Key Terms Here… The 2 main character sets are American Standard Code for Information Interchange and unicode Key People… Key Dates… Main Themes… -special characters are things like emojis and alphanumeric characters are things like letters When you have finished writing your notes, go back through and extract all key terms write them in the Left column… Summary - If you were explaining this area of the Curriculum to someone else, this is what you would tell them... Topic: Write Top Compression techniques Key Terms Write notes/Draw Diagrams here Write Key Terms Here… Lossy compression -permanently removes some data Key People… -it recreates the file using the remaining data and uses algorithms to to guess the removed content Key Dates… Lossless image compression -it finds groups of repeating data and records it only once along with the number of Main Themes… times it is used Some benefits of compression-increases,download speed,opens quicker,gets more storage free Buffering means when the download speed is slower than the playback speed Why use compression? Download speeds are increased Data allowances are reduced Voice can be transmitted fast enough to keep up with speech When you have finished writing your notes, go back through and extract all key terms write them in the Left column… Summary - If you were explaining this area of the Curriculum to someone else, this is what you would tell them... Topic: Write Top Comppresstion Key Terms Write notes/Draw Diagrams here Write Key Terms Here… Lossy compression-JPG,GIF,MP3 Lossless compression-PNG,TIF,SVG Key People… Compression is mainly used for images,videos and audio Compressed data is not the same as the original Key Dates… Main Themes… When you have finished writing your notes, go back through and extract all key terms write them in the Left column… Summary - If you were explaining this area of the Curriculum to someone else, this is what you would tell them... Topic: Write Top Environmental issues Key Terms Write notes/Draw Diagrams here Write Key Terms Here… Key People… Key Dates… Main Themes… Gas and coal are needed to power factories and the are non renewable resources Plastic Non-renewable Steel Non-renewable Gold Non-renewable Copper Non-renewable Aluminium Non-renewable Fiberglass Non-renewable Diesel Non-renewable Water Renewable Raw metal is found in veins under the earth and dug up E-waste is hurting the environment because it often ends up in landfill and toxic chemicals are released into the atmosphere To improve e-waste you can buy second hand devises and trade in your old phones to a store such as CEX or make sure it is recycled not just throne away  When you have finished writing your notes, go back through and extract all key terms write them in the Left column… Summary - If you were explaining this area of the Curriculum to someone else, this is what you would tell them... Topic: Write Top Wired and wireless networks Key Terms Write notes/Draw Diagrams here Write Key The internet is a interconnected networks Terms Here… The internet is world wide DNS stands for domain name services Key People… The world wide web is what you access on the internet so not the same thing WAM stands for wide area network Key Dates… Apple watches have a PAN PAN stands for personal area network Main Themes… IP stands for internet protocol When you have finished writing your notes, go back through and extract all key terms write them in the Left column… Summary - If you were explaining this area of the Curriculum to someone else, this is what you would tell them... Topic: Write Top Programing sequences and Rocketbook scan called ssi1 selection Key Terms Write notes/Draw Diagrams here Write Key Constructs Terms Here… -sequence -seleccion Key People… -iteration  An IF statement is a selection statement along with elif, else Key Dates… A while and for statement is iteration Iteration means loop Main A sequence is when it goes through the code line by line Themes… Anything that doesn’t have a IF statement or a while loop is a sequence   Worksheet Worksheet task 1 Worksheet task 2 Static ip addresses allow you to see where you are Any device connected to a network or internet has a ip address MAC addresses are a address that every bit of hardware has When you have finished writing your notes, go back through and extract all key terms write them in the Left column… Summary - If you were explaining this area of the Curriculum to someone else, this is what you would tell them... Topic: Write Top LAN networks Key Terms Write notes/Draw Diagrams here Write Key Terms Here… LAN stands for local area networks PAN stands for personal area network such as airpods and apple watches Key People… Key Dates… Main Themes… Network topologies(topologies is essentially a fancy word for layout)  The school uses a star network  Full mesh means everything it connecting to everything whereas partial mesh network only connects to some  When you have finished writing your notes, go back through and extract all key terms write them in the Left column… Summary - If you were explaining this area of the Curriculum to someone else, this is what you would tell them... Topic: Write Top Wired and wireless networks Key Terms Write notes/Draw Diagrams here Write Key Terms Here… Key People… Key Dates… Main Themes…  When you have finished writing your notes, go back through and extract all key terms write them in the Left column… Summary - If you were explaining this area of the Curriculum to someone else, this is what you would tell them... Topic: Write Top Wired and wireless network Key Terms Write notes/Draw Diagrams here Write Key Terms Here… Key People… Key Dates… Main Themes…  Role of a client: -the client sends requests to the server -waits for a reply -receives the reply Role of the server: -the server waits for the clients request -agnolages the request -the requested data is sent to the client     One advantage to cloud data is you can access it anywhere that has internet connection One disadvantage to cloud data is if the wifi goes out you won't have access One disadvantage of cloud data is that if you forget your passwords and usernames you won't be able to access your data  When you have finished writing your notes, go back through and extract all key terms write them in the Left column… Summary - If you were explaining this area of the Curriculum to someone else, this is what you would tell them... Topic: Write Top Wired and wireless networks Key Terms Write notes/Draw Diagrams here Write Key Terms Here… Key People… Key Dates… Main Themes… FTP(file transfer protocol)-used for sending or retrieving files to or from a remote server or computer     When you have finished writing your notes, go back through and extract all key terms write them in the Left column… Summary - If you were explaining this area of the Curriculum to someone else, this is what you would tell them... Topic: Write Top Network security Key Terms Write notes/Draw Diagrams here Write Key Cyber attacks take advantage of human weakness and gullibility or technical Terms Here… weaknesses Social engineering is the art of manipulation Key People… Phishing is fake emails 5% of phishing is successful Key Dates… Main Themes… Shoulder suffering is when someone directly watches you entering their security details such as watching someone enter there pin at a atm Brute force attack is when you force your way in usually by using lots of different passwords To counter brute force attacks you need to limit the attempts you get before your locked out  When you have finished writing your notes, go back through and extract all key terms write them in the Left column… Summary - If you were explaining this area of the Curriculum to someone else, this is what you would tell them... Topic: Write Top Defensive design Key Terms Write notes/Draw Diagrams here Write Key Terms Here… Key People… Key Dates… Main Themes…  It is a length check A contingency plan is a plan for what to do if something unexpected happens Authentication routines are used to make sure a person is who they claim to be Sirs replit with the types of checks: here My replit with the type of checks: here  When you have finished writing your notes, go back through and extract all key terms write them in the Left column… Summary - If you were explaining this area of the Curriculum to someone else, this is what you would tell them... Topic: Write Top Errors and testing Key Terms Write notes/Draw Diagrams here Write Key Terms Here… Key People… An IDE is a program that lets you use high level language in a environment Replit is a IDE Key Dates… An editor which allows you to write and correct your program and provides help in writing correct syntax(the part in replit you type your code in) Main Themes… A compiler or interpreter to translate your program into machine code (1 and 0) Error diagnostics to point out syntax errors A runtime environment so you can run your program (the part in replit that your run  the program) Logic errors Logic errors in a program are mistakes in the algorithm you have devised to perform the required task A trace table is useful for tracing through a program in order to find a logic error Syntax error A code that does not follow the syntax of a programming language Testing A successful test is one which uncovers a problem/error Valid data,invalid data,boundary data  When you have finished writing your notes, go back through and extract all key terms write them in the Left column… Summary - If you were explaining this area of the Curriculum to someone else, this is what you would tell them... Topic: Write Top Network safety Key Terms Write notes/Draw Diagrams here Write Key Terms Here… USB ports are a gate for attacks Attacks often happen in person as well like leaving our laptop unattended Key People… 25% of malware is spread through USB sticks eavesdropping intercepts packets when travelling across a wire Key Dates… Digital stalking is when on older social media the latitude and longitude that the picture was taken from Main Back doors are weak points Themes… Strong passwords are a good first steps DoS attacks (denial of service ) attempt to flood a website When you have finished writing your notes, go back through and extract all key terms write them in the Left column… Summary - If you were explaining this area of the Curriculum to someone else, this is what you would tell them... Topic: Write Top Identifying and preventing green=keyword vulnerabilities Key Terms Write notes/Draw Diagrams here Write Key Penetration testing is when you purposely try to find holes in your security Terms Here… Black box testing is when testers are only given the amount of information a real hacker would have Key People… White box testing is when testers are given as much information as an insider(employee) to test how much damage a rogue employee could do Key Dates… Hackers can be split into 2 groups based on their motives black hat hackers have criminal intent Main Ethical hackers also known as white hat hackers are employed by companies to Themes… find weaknesses Grey hat hackers find vulnerabilities without authorisation from the owner and usually hold the information for ransom with the threat of releasing it without actually doing anything with the information themself Firewalls act like a filter for what enters and doesn't to your computer In Https the s stands for secure Audit trails records data such as who attempted access,what they did,where did they look,when did they do it To counter brute force attacks you can set a limit to how many tries to get before it locks When you have finished writing your notes, go back through and extract all key terms write them in the Left column… Summary - If you were explaining this area of the Curriculum to someone else, this is what you would tell them... Topic: Write Top Logic gates  green=keyword Key Terms Write notes/Draw Diagrams here Write Key Terms Here… Key People… Key Dates… Main Themes… When you have finished writing your notes, go back through and extract all key terms write them in the Left column… Summary - If you were explaining this area of the Curriculum to someone else, this is what you would tell them... Topic: Write Top Search algorithm green=keyword Key Terms Write notes/Draw Diagrams here Write Key Terms Here… Binary search-is performed on sorted data when the mid point is found and compares if it is what you're looking for if not find what half it is on and halves that Key People… side and repeats till found Linear search-is goes through every bit of data to see if it is the same as you are Key Dates… searching for so if there are 400 bits of data it will search all 400 parts Main Themes…  When you have finished writing your notes, go back through and extract all key terms write them in the Left column… Summary - If you were explaining this area of the Curriculum to someone else, this is what you would tell them... Topic: Write Top Sorting algorithms green=keyword Key Terms Write notes/Draw Diagrams here Write Key Terms Here… Bubble sort: A pass is when it reaches the end but if it makes a swap on that go it must go from Key People… the beginning to check again but if it passes to the end without a swap it is sorted A bubble sort looks at the first to values and looks at if the first number is larger than Key Dates… the other and if so it swaps them Main Themes… Insertion sort: Insertion sort leaves the first item at the start. Then looks at the next item and inserts it into the correct place  The first number never moves and stays the same Merge sort: You merge groups of singles to groups of 2 to groups of 4 to groups of 8  When you have finished writing your notes, go back through and extract all key terms write them in the Left column… Summary - If you were explaining this area of the Curriculum to someone else, this is what you would tell them... Topic: Write Top Operating system green=keyword software Key Terms Write notes/Draw Diagrams here Write Key Terms Here… Key People… Key Dates… Main Themes… Operating system-software manages a computer's hardware and provides a user interface  Windows is a WIMP interface WIMP stands for windows,icons,menus and pointers   Peripherals are all the devices outside the cpu When you have finished writing your notes, go back through and extract all key terms write them in the Left column… Summary - If you were explaining this area of the Curriculum to someone else, this is what you would tell them... Topic: Write Top Utility software green=keyword Key Terms Write notes/Draw Diagrams here Write Key The purpose of utility software that makes the computer work properly and Terms Here… efficiently  Encryption Key People… -encrypts the data -make it so if found it is useless without the key Key Dates… -mostly used for files and folders,portable sticks ,web communication and databases Main Disk organisation Themes… -file management and transfer -disk fragmentation - Data compression -the reason we compress data we send over the internet so it makes the process quicker and takes up less bandwidth Backups -full backup-complete backup of everything -incremental backup-only backs up the changes made since last backup When you have finished writing your notes, go back through and extract all key terms write them in the Left column… Summary - If you were explaining this area of the Curriculum to someone else, this is what you would tell them...  Topic: Write Top Ethical and cultural issues green=keyword Key Terms Write notes/Draw Diagrams here Write Key technology in health care Terms Here… Wearable technology can offer long term and continuous monitoring It can help with how diseases like epilepsy,,asthma and diabetes are managed Key People… The technology in healthcare can be expensive to set up and get Another disadvantage is you data could be sold to 3rd party people Key Dates… Technology in shopping Main With online shopping it allows companies to buy/rent cheaper locations as it is less Themes… important Staff dont have to restock shelves as much The iteam may not fit as it was not tried on When you have finished writing your notes, go back through and extract all key terms write them in the Left column… Summary - If you were explaining this area of the Curriculum to someone else, this is what you would tell them... Topic: Write Top Environmental issues green=keyword Key Terms Write notes/Draw Diagrams here Write Key Terms Here… Key People… Key Dates… Main Themes…  When you have finished writing your notes, go back through and extract all key terms write them in the Left column… Summary - If you were explaining this area of the Curriculum to someone else, this is what you would tell them... Topic: Write Top Legislation and privacy green=keyword Key Terms Write notes/Draw Diagrams here Write Key Data protection act:is about looking after personal details of people Terms Here… Key People… Key Dates… Main Themes… Data must be stored so that -the data is kept accurate and up to date -it is not kept any longer than necessary -it must not be transferred to other countries unless they can keep it protected -customers must be told of a data breach within 72 hours of it happening  When you have finished writing your notes, go back through and extract all key terms write them in the Left column… Summary - If you were explaining this area of the Curriculum to someone else, this is what you would tell them... Topic: Write Top Defensive design green=keyword Key Terms Write notes/Draw Diagrams here Write Key Terms Here… Key People… Key Dates… Main Themes… Validation can only check that the data entered is reasonable Verification is used to double check that the data has been typed in correctly In anticipation of brute force attacks you limit the number of attempts at a passwords  When you have finished writing your notes, go back through and extract all key terms write them in the Left column… Summary - If you were explaining this area of the Curriculum to someone else, this is what you would tell them... Topic: Write Top Errors and testing green=keyword Key Terms Write notes/Draw Diagrams here Write Key Terms Here… An IDE is a integrated development environment -replit is a IDE Key People… -they have code completion (the ai part that tells you what you could write) -they have error diagnostics Key Dates… -a runtime environment (the part where your code is ran) Syntax errors are grammatical problems with your code Main Themes… When you have finished writing your notes, go back through and extract all key terms write them in the Left column… Summary - If you were explaining this area of the Curriculum to someone else, this is what you would tell them... Topic: Write Top High level and low level green=keyword languages Key Terms Write notes/Draw Diagrams here Rocket book Write Key Terms Here… Low level languages are closer to what a computer can understand such as binary High level language it is closer to english like repl Key People… It is easier to write and debug high level High level needs to be translated into machine code Key Dates… Low level languages can directly access memory Main Themes… When you have finished writing your notes, go back through and extract all key terms write them in the Left column… Summary - If you were explaining this area of the Curriculum to someone else, this is what you would tell them... Topic: Write Top Translator,inter preters and green=keyword compliers Key Terms Write notes/Draw Diagrams here Write Key Terms Here… Key People… Key Dates… Main Themes…  When you have finished writing your notes, go back through and extract all key terms write them in the Left column… Summary - If you were explaining this area of the Curriculum to someone else, this is what you would tell them...