This also facilitates multitasking, with each core being to process different programs’ instructions at the same time. In the table above, subject, tier, productID, custName and custSurname can be definded as the secondary key.

The CPU in reality checks for the data in the (L1) cache first and uses this before checking RAM - if it exists, it’s a cache hit as opposed to a cache miss. Welcome to the A Level OCR Computer Science H446 Cheat Sheet, with everything covered in detail in the specification. A virtual machine is any instance when software is used to emulate another machine, such as running another OS inside another (e. Antivirus - scans secondary and even primary storage for known virus definitions (requires regular updates), or use heuristic analysis to detect suspicious behaviour. This means that any circuit can be built from a single type of logic gate, which reduces manufacturing costs as only one type of gate can only be used.

The priority queue structure moves the connected values to the start of the queue, with the next closest being moved to the front. TCP is a sequential stream but is slower due to ACK packets (acknowledgement) and can cause packets to queue and ping spikes.

The clock width is the length of one pulse - the shortest time possible between the rising and falling edges. A router is a network device that receives packets and forwards data packets from one network to another.These devices connect computers and other devices in a network, allowing them to communicate and share resources. If Program A requires 2 pages of RAM, it gets loaded into the first 2 memory addresses which correspond to these pages.

Referential integrity states that an attribute referenced as a foreign key on one table cannot be deleted, and therefore cannot reference something that doesn’t exist. Even if you haven't studied Computer Science before, if you enjoy problem solving and are logical and good at Maths then this is the right course for you.The control unit (CU) within the CPU is responsible for controlling all operations that occur within the CPU in other subunits and registers of the processor such as the ALU (Arithmetic Logic Unit), and how this data is exchanged to other registers or moved around the system.

Linked lists are dynamic lists toom as the link item points to the memory address of the next item in the array, if there is one. Changing the attributes of an HTML element: // Get element with id "example" from the DOM var chosenElement = document . While one job is transferring data onto a USB stick or printing, another job can be mining bitcoins which requires CPU[ 3] calculations. Nowthatmake'ssense,acandidatewillclearlybeabletodistinguishtheknowledgethatisrelevanttohimregardingtheALUandwhatisnot,theysimplyneedtoknowit'sfunctionandpurpose.uk 4 TEACHING CONTENT 1 Understand concepts of equality, diversity and rights in relation to health and social care • Social, cultural and economic diversity: (e. These subsequent modification requests can then be blocked until the initial transaction is committed. Our A Level Computer Science qualification helps students understand the core academic principles of computer science. If you are designing a system for a company that sells subscriptions for online revision resources, a flat file would not be useful. This may also be off the shelf for things like browsers, or be more ‘niche’ such as electronic exam marking applicaions or fingerprint scanning systems, or DBMS.