AQA Physics Electricity and Core Practicals

Computer Systems and Networks: Key Concepts and Attacks

• Binary addition follows the same rules as normal addition, but with the addition of carrying a 1 to the next column when necessary.

• Binary shifts involve either adding or removing digits. A left shift doubles the number, while a right shift halves the number.

• Overflow errors occur when the result of an operation takes up more storage space than is available, resulting in a wrong version of the number being stored.

• Character sets, such as ASCII and Unicode, allocate binary numbers to represent characters, with Unicode allowing for a larger number of characters.

• Images are represented as pixels, and the resolution of an image refers to the number of pixels it contains.

• Color depth refers to the number of bits allocated to each pixel in an image, and metadata is stored to provide additional details about the image.

• Sound is converted from analog to digital by taking samples of the amplitude at regular time intervals, with the sample rate determining the number of samples per second.

• Bandwidth refers to the maximum amount of data that can be transferred at any given time on a network, and sharing bandwidth among devices can slow down transmission.

• Local Area Networks (LANs) cover a small area, while Wide Area Networks (WANs) cover a larger area and often have infrastructure owned by multiple entities.

• In client-server networks, devices take on the roles of either a client or a server, with the server responding to client requests. In peer-to-peer networks, devices can act as both clients and servers.

• Network topologies include star (reliant on a central device) and mesh (direct connections to every device), each with their own advantages and disadvantages.

• Protocols are a set of rules enabling devices to communicate, and TCP splits data into packets, while POP, IMAP, and SMTP are email protocols.Multitasking and Memory Management in Operating Systems

• Operating systems support multitasking, which allows for the execution of multiple programs simultaneously.

• Multitasking involves rapidly switching between the programs being executed.

• The operating system determines when to move data across memory and when to delete data from RAM.

• Memory management is a crucial function of the operating system.

• RAM (Random Access Memory) is a type of memory used by the operating system to store program instructions and data.

• The operating system decides which tasks should be executed based on priority and resource availability.

• Multitasking creates the illusion of multiple tasks happening at once, even though they are rapidly switched between.

• Peripherals are external devices connected to the computer, such as keyboards, mice, and printers.

• Peripherals are managed by the operating system.

• The operating system handles the communication between the peripherals and the computer.

• The operating system ensures that the peripherals function properly and interact with the computer as intended.

• Multitasking and memory management are essential for efficient and effective computer operation.

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