AQA 2023 GCSE COMPUTER SCIENCE 8525 Paper 1, 2 Question Papers & Mark schemes

AQA 2023 GCSE COMPUTER SCIENCE 8525 Paper 1, 2 Question Papers & Mark schemes NOT Gate - Line above letter - ANSWERSA logic gate that takes a single input and outputs the opposite value AND Gate - (A.B) - ANSWERSA logic gate that takes in 2 inputs and only outputs True if both inputs are True (A.B) XOR Gate - A ⊕ B - ANSWERSA logic gate that takes two inputs and outputs true if the inputs are different. OR Gate - (A+B) - ANSWERSA logic gate that takes two inputs and outputs True if either input is True Binary - ANSWERSA representation of the flow of electricity within a computer. 1 is flow, 0 is not. Data units and sizes - ANSWERSBit (b), Nibble, Byte (B), Kilobyte (KB), Megabyte (MB), Gigabyte (GB), Terabyte (TB) Binary shifts - ANSWERSThe method to multiply or divide a binary number by 2 by moving a binary number to the left to multiply and to the right to divide. Hexadecimal - ANSWERSA base-16 number system, consisting of the 16 symbols 0 through 9 and A through F. ASCII - ANSWERSEach character is given a 7-bit binary code, meaning it can represent a total of 128 different characters. Unicode - ANSWERSA character code that enables most languages, it uses multiple bytes for each character. More than 1mil+ characters Bitmap - ANSWERSA type of image comprised of pixels.(Width * Hight) Formula for calculating the number of colours stored in a pixel - ANSWERS2 to the power of the colour depth. Analogue signal - ANSWERSA continuous signal that varies in amplitude or frequency with the information being transmitted. The form of data that sound is recorded as; that must be converted to digital data to be read by a computer. Sampling - ANSWERSThe process of converting analogue data into digital data through sampling the amplitude of the wave at regular intervals. Sample resolution - ANSWERSThe number of bits used to store the value of each sample. The higher the number of bits the more accurately the value is stored.. Formula for calculating the size of a sound file - ANSWERSSample rate (in Hz) * sample resolution * length (in secs). AQA 2023 GCSE COMPUTER SCIENCE 8525 Paper 1, 2 Question Papers & Mark schemes Sample rate - ANSWERSThe number of samples taken per second, measured hertz. Data compression - ANSWERSReducing the amount of space needed to store a piece of data Lossy compression - ANSWERSA data compression technique that permanently removes some data from the file. Used for MP3, AAC, JPEG. Lossless compression - ANSWERSA data compression technique that temporarily removes data. The original version of the data can be restored. Run-Length-Encoding (RLE) - ANSWERSA form of lossless compression that looks for consecutive repeating data in a file. It stores the number of times it repeats and one copy of the data. Huffman coding - ANSWERSEncoding more frequent letters/pixels with shorter bit representations and less frequent ones with longer bit representations. What are embedded systems - ANSWERSComputers built into other devices such as a dishwasher, they are usually dedicated systems. They are most often used as control systems. What are the advantages of embedded systems - ANSWERSThey're usually easier to design, cheaper to produce and more efficient than a general purpose computer due to them being dedicated to one task What are the 5 main parts of the CPU - ANSWERSThe Control Unit (CU), the Arithmetic Logic Unit (ALU), Registers, Clock, Buses Control unit (CU) - ANSWERSThe part of the CPU that is in overall control of the CPU, its primary job is to execute program instructions by following the fetchdecode-execute cycle. Arithmetic Logic Unit (ALU) - ANSWERSThe part of the CPU that carries out calculations and logical operations. The Clock - ANSWERSA part of the CPU that sends out a signal that continually cycles between 1 and 0 at a constant rate. Buses - ANSWERSA collection of wires that are used to transmit data between components of the CPU, and to other parts of the computer system. Cache Memory - ANSWERSHigh-speed memory that stores frequently needed instructions or data. Stores copies of data or instructions from the RAM that are accessed very regularly