Download OCR A LEVEL Computer Science H446/02 JUNE 2025 QUESTION PAPER MERGED WITH MARK SCHEME. and more Exams Advanced Education in PDF only on Docsity!
OCR A LEVEL Computer Science H446/
JUNE 2025 QUESTION PAPER MERGED WITH
MARK SCHEME.
1 Dimensional Arrays - ANSWERA standard list array - one index is needed to search for something in an array. 2 Dimensional Arrays - ANSWERAn array with 2 indexes needed to search - for example a table could be this. Interception of PseudoCode - ANSWERThe ability to pick out and explain parts of code. Big O' - ANSWERA measure of complexity within a piece of code. Recursion - ANSWERThe process of looping, calling itself in looping. Functions - ANSWERA decomposed part of code that has a specific job to output or return something Iteration - ANSWERRepeating some part of code over and over Subroutine - ANSWERA decomposed part of problem that does something Data Mining - ANSWERThe process of collecting data on user habits or requests
Binary Search - ANSWERA search algorithm that includes comparing the midpoint of an array iteratively. Insertion Sort - ANSWERA sorting algorithm that includes going through an array iteratively comparing each value to every value before that value. Bubble Sort - ANSWERMoving through a list, it compared two elements and moves on, moving through the array repeatedly. Quick Sort - ANSWER Merge Sort - ANSWER Global Variable - ANSWER Local Variable - ANSWER Dijkstra's Algorithm - ANSWER Travelling Salesman Algorithm - ANSWER Decomposition - ANSWER Graph Tree - ANSWER
Memory Address Register (MAR) - ANSWERA register in the CPU that stores the address of the memory location currently in use. In the fetch phase, this would be the address of an instruction; in the execute phase, it would be the address of the data being used. Memory Data Register (MDR) - ANSWERUsed to temporarily store data loaded into the CPU, or written to memory locations. All transfers from memory locations to the CPU go via the Memory Data Register. Current Instruction Register (CIR) - ANSWERA register in the control unit that stores the instruction type of the next instruction to be carried out by the processor. For example, this could contain the number 3, which in LMC is a 'store' function. Buses - ANSWERA common physical pathway for signals to travel to and from several components of a computer. Data Bus - ANSWERTransfers the data from memory location specified by MAR. Address Bus - ANSWERThe part of the bus which carries information about where the data is being sent. Control Bus - ANSWERThis bus carries command and control signals to and from every other component of a computer. Fetch - ANSWERDecode-Execute - The complete process of retrieving an instruction from a memory source, decoding it and carrying it out (execution). Also known as the instruction cycle.
Central Processing Unit (CPU) - ANSWERThe main part of the computer, consisting of the registers, ALU and control unit. Clock Speed - ANSWERMeasured in Hertz, the clock speed is the frequency at which the 'internal clock generates pulses'. This means how fast it can execute instructions. The higher the clock rate, the faster the computer may work. The "clock" is an electronic unit that synchronizes other components by generating pulses of electricity at a constant rate (almost like waves). Cores - ANSWERA CPU is one 'Core'. A multi-core processor is a single component with two or more independent actual CPU's, which are the units responsible for the fetch-decode-execute cycle. Theoretically, this could 'double' speed but depends on efficiency of splitting up tasks. Cache - ANSWERA part of the main store between the central processor and the RAM. It has extremely fast access, so sections of a program and other data is copied there to take advantage of its short fetch cycle. LMC STA - ANSWERStore function, puts the value in the accumulator into the storage location specified. LMC LDA - ANSWERLoads data from the storage location specified into the accumulator. LMC BRA - ANSWER'Branches' the next instruction to the address given. LMC BRP - ANSWER'Branches' the next intruction to the address given if the value in the accumulator is positive or zero.
Contemporary Architecture - ANSWERUsually a combined selection of the 2 basic architectures' - taking the best of both worlds. Simplicity of Von Neumann, but the useful features of Harvard. Input Device - ANSWERAny peripheral device that can accept data, presented in the appropriate machine-readable form, decode it and transmit it as electrical pulses to the CPU. Output Device - ANSWERAny peripheral device that translates signals from the computer into a human-readable form or into a form suitable for reprocessing by the computer at a later stage. Storage Device - ANSWERAny medium (optical, magnetic, solid state and even paper which holds data or programs. Magnetic Storage - ANSWERStorage medium which uses surfaces coated with a layer of magnetic material on which data can be stored by magnetically setting the arrangement of the magnetic material. This is done by electromagnetic read/write heads. Flash Storage - ANSWERCollection of memory chips that is controlled by its own software to make the collection of chips act like a disk drive. Compact, large storage medium. Optical Storage - ANSWERStorage medium that uses plastic discs on which the data is stored as patterns on the surface in pits and lans. Lightweight, compact, limited by data size.
Solid State Storage - ANSWERStorage medium for main disk drive on a computer, is generally more expensive, therefore less storage space, however is more reliable. Hard Disk Drive - ANSWERStorage medium for main disk drive on computer, is generally cheaper, therefore more storage space, however can be unreliable. Random Access Memory (RAM) - ANSWERVolatile main memory. Access times are very fast. Often referred to as Main Memory, although this can be used in main areas of computing and computing storage. When used as main memory this typically can be thought of as containing the Operating System, programs in use and the data those programs are using while the computer is running. Read Only Memory (ROM) - ANSWERMemory for which the contents may be read by cannot be written to by the computer system. Software in ROM is fixed during manufacturing. It typically holds system boot up instructions. ROM is non-volatile. More modern types of ROM can be written to in limited ways, these include, PROM, EPROM and EAROM. Virtual Memory - ANSWERA means of extending main storage by using the hard drive as if it were quick-access memory. Operating System is expected to utilise this by prioritising tasks. Virtual Storage - ANSWER'The Cloud'. Reduces duplication, can be accessed remotely but is less secure and is reliant on bandwidth. RAM Advantages - ANSWERVolatile so doesn't get clogged up, large storage size, quick access.
on face-to-face communication rather than massive amounts of written documentation. Extreme Programming - ANSWERA software development methodology which has many branches - its main goal is to use short development cycles to test often and work collaboratively. One 'type' of Extreme programming is working in pairs to complete a task, with some looking at the larger picture of the code, while others looking closely at every little bit of code. Spiral Model - ANSWERAnother cycle of system development, there are four defined 'quadrants' - planning, risk analysis, use of design methods, client and management evaluation. Once one stage of development has gone full 'circle', the next phase takes place, and so on until completion. Rapid Application Development (RAD) - ANSWERA design strategy that includes online development and repeated prototyping and evaluation. It is particularly suited to interactive systems, where the user plays an active part in the program, or even programming. Black Box Testing - ANSWEROutputs are checked after inputs are given. Code is hidden. White Box Testing - ANSWEREach line of the code is tested, therefore code is understood. Alpha Testing - ANSWERA small group test an unfinished product with known errors. Database - ANSWERA collection of organised data.
Relational Database - ANSWERMultiple tables that a user can find relationships between and find specific information. Flat File - ANSWERA database that can be stored at a plain text file. One record (row), with fields (column) separated by tabs or commas. Fields - ANSWER'Headings' for the data to be organised when inputted - e.g. name, DOB etc. Record (databases) - ANSWERA specific row of data. For example, John Smith, 25/01/2002. Primary Key - ANSWERA field that uniquely identifies a record in a table. For example, a User ID. Foreign Key - ANSWERThe linking field in a foreign table, formed when a relationship between 2 databases is formed. The Foreign Key becomes the Primary Key of the new table. A foreign key could be a User ID. Concatenated (attached) Primary Key - ANSWERMore than one field is added together to form a unique primary key for a table. For example, 'group ID' and 'specific person ID'. Secondary Key - ANSWERA key field which can be used to index the data in a different order - for example you could sort the data by surname (the secondary key) rather than the primary key (User ID).
Normal Forms - ANSWERA way of structuring the data in a relational database according to a set of rules, in order to avoid problems of inefficiency in accessing and maintaining the data. For example, 1NF, 2NF, 3NF. Entity Relationship Modelling (ERM) - ANSWERThe production of a data model for describing data and its organisation within a database. ERM One-to-One - ANSWEROne database can only equal one other row in the database. For example, a country can only have one capital city. [London]----[England] ERM One-to-Many - ANSWEROne database can be equal to multiple rows in the other table. For example, a student can take more than one course (many). [Student]---<[Course] ERM Many-to-many - ANSWERNot possible as it would result in data redundancy. For example, 'many students take many courses of which take many students'. To fix, you either need a new database or you will need to priorities whether you need to know about the student's many courses or the course's many students. Structured Query Language (SQL) - ANSWERThe language and 'syntax' used to write and run database queries. SQL SELECT - ANSWERWhat fields do you want to display? SQL FROM - ANSWERWhich table(s) would you like to use to display data from?
SQL WHERE - ANSWERWhat search criteria are you going to use to choose records? Search criteria is a boolean statement and is phrased 'where this is true'. When changing records, this is used to set the record which would be updated. SQL AND, OR, NOT - ANSWERFor SQL WHERE statements, these are boolean statements that, in order, needs both criteria to be true; one or both to be true; the opposite to what is true. AND - ANSWER^ symbol signifies ... can also be written as .(sometimes this. is dropped and it is just shown as XY) OR - ANSWER∨ symbol that signifies ... can also be written as + NOT (negation) - ANSWER¬ symbol signifies ... can also be written as x̄ XOR - ANSWER⊕ symbol signifies ... B^AvB^C - ANSWERB(AvC) is simplified to ... X - ANSWERXv(XY) simplifies to ... (AND's & OR's can be switched for the same ANSWER) X - ANSWERX^X is equal to ... X - ANSWERXvX is equal to
SQL * - ANSWERA 'wildcard'. Means everything in query. SQL UPDATE - ANSWERWhen you want to update a record, this phrase tells the program which table needs updating. SQL SET - ANSWERWhat needs to be changed - describe the change. For example, 'room' could be changed to a different code. SQL INSERT INTO - ANSWERWhen inserting data is needed, this says which fields will be added to - eg. teacher name, room etc. SQL VALUES - ANSWERSets the values which will be inserted into the fields specified beforehand. eg. 'Mr White' , 'D3'. Referential Integrity - ANSWERA measure of the consistency of the data in a database. It is violated when a foreign key which a table refers to no longer exists. Transaction Processing - ANSWERInformation processing that is divided into individual, indivisible operations, called transactions. Each transaction must succeed or fail as a complete unit, it can never be only partially complete. For example, when buying a book, a number of transactions (information exchanges) must occur to ensure the book is accounted for, and you are giving the money to the shop. Any one of these transactions fail, the whole transaction fails, therefore ensuring you do not get the book without paying or vice versa.
Atomicity, Consistency, Isolation, Durability (ACID) - ANSWERA set of properties that guarantee that database transactions are processed reliably. For example, a single logical operation on the data is called a transaction. Atomicity re-enforces the rule of full completion or failure. Consistency is a filter that ensures data is in the correct format. Isolation is the isolation of processes, ensuring a transaction is secure and doesn't get mixed up. For example, user A wants to withdraw £100, and user B wants to withdraw £ from account Z, User A's transaction should be validated and finished before User B's even begins. Durability is the idea of ensuring that a client or business is not 'ripped-off' if a failure is seen. For example, if User A's transaction fails, the £100 should not still be taken from the account. Record Locking - ANSWERA technique of preventing simultaneous access to data, to stop data inconsistences or double data. For example, two bank clerks updating a client's information on a banking databases at the same time. Redundancy - ANSWERThis occurs in database systems which have a field that is repeated in two or more tables. For instance, when customer data is duplicated and attached with each product bought, then an inconsistency in found, since the customer might change these attributes - both tables must change rather than one. Primitive Data Types - ANSWERThe basic data types provided by a programming language as building blocks. Most languages allow more complicated types. E.g. char, integer, float, Boolean. A 'string' data type is constructed behind the scenes of many char data types. Integer - ANSWERA data type used to store positive and negative whole numbers.
Denary - ANSWERA numerical system that uses 10 as its base. The 10 Decimal base digits are 0-9. This is how we 'normally' count. Floating Point Arithmetic - ANSWERPerforming simple calculations on more than one floating-point number stored in binary notation. Bitwise Manipulation - ANSWERAlgorithmically manipulating bits. Programming tasks that require a 'bit manipulation' include low-level device control and error detection, data compression, encryption algorithms, and optimisation. Shifts - ANSWERAn operation that moves the bits held in a register, called the shift register, either to the left or the right. There are three different types of shift: arithmetic shift, logical shift and cyclic shift. They are distinguished by what happens to the bits that are shifted out of the register at one end and what is moved in to fill the vacant space at the other end. AND - ANSWERA logical operator. This works by only returning TRUE (1) if both values being compared are TRUE (1). OR - ANSWERA logical operator. This works by returning TRUE (1) as long as either value being compared is TRUE (1). XOR - ANSWERA logical operator. This will return TRUE (1) only if the two items being compared are different. Character Sets - ANSWERThe set of symbols that may be represented in a computer. These symbols, called characters, can be letters, digits, spaces or punctuations marks represented in binary, or hexadecimal.
America Standard Code for Information Interchange (ASCII) - ANSWERA character set created for early telecommunication systems in 1963, but proved to be ideal for computer systems. This set uses 7-bits giving 32 control codes and 96 displayable characters (the 8th bit is often used for error checking). UNICODE - ANSWERStandard character set that replaces the need for any other character set. It incorporates characters from almost all the world's languages. It is a 16-bit extension of ASCII. Abstract Thinking - ANSWERThe simplification of data, the removal of redundant data that is not necessary. For example, a flight simulator does not need to render individual people on the ground, or intricate detail on buildings - instead it should focus on the weather or cockpit detailing. Ethics - ANSWERRefer to rules provided by an external source, e.g., codes of conduct in workplaces or principles in religions. Morals - ANSWERRefer to an individual's own principles regarding right and wrong. Sequence - ANSWERA series of instructions after one another. Selection - ANSWERA series of intructions but with a choice or branch. For example, IF Iteration - ANSWERA series of intructions repeated - Loops.
