CPU - Refers to the part of the computer responsible for processing and executing all instructions, Registers - Small but fast memory location on the CPU, used to hold instructions or storage address, Clock - Controls the number of instructions carried out per second, Control unit - Controls the fetching, decoding and writing of data during the CPU cycle, ALU - Responsible for carrying out arithmetic and logic operations, Buses - Allows data to be transferred between internal CPU components, Clock speed - Each instruction starts on a clock pulse. The more pulse per second the more instruction are likely to be carried out, Number of cores - Affects the number of instructions that may be executed simultaneously (or in parallel). Different cores deal with different type of instructions, Cache size - Instructions take less time to transfer to the processor from the cache because cache is held closer to the processor. The more cache the more data that can be held closer to the CPU, Fetch - CPU fetches the next instruction from main memory, Decode - The instruction is decoded so the CPU knows what to do with the instruction, Execute - The instruction is carried out and this may involve reading from/writing to main memory, RAM - Stores running application while the computer remain on, ROM - Stores the instruction needed to turn on the computer (BIOS), Cache memory - High speed amount of temporary memory which is used to store most frequently accessed instructions from the RAM, HLL e.g. - Python, Java, C++, LLL e.g. - Assembly language, machine code, Secondary memory - Saves all our data long term, after the power to the device is turned off (also used to transfer files from device to device), Magnetic e.g. - HDD, Floppy disk, Magnetic tape, Optical e.g. - CD, DVD, Blu-ray, Solid state e.g. - SSD, SIM card, SD card, USB drive, Magnetic pros/cons - Cheaper per GBs of memory, larger capacity but easily damaged due to moving parts, slow, loud, How is magnetic memory read? - Magnetic heads are components attached to an actuator arm that moves over the spinning disk. Platters are the circular disks coated with a magnetic material. Data is stored on these platters in the form of a magnetic pattern. During the read process, the magnetic heads do not physically touch the platters. The heads are positioned very close to the platters, creating a small gap. The magnetic heads read changes depend on the magnetic orientation of the particles on the platters. This process is what represents the binary data. Data is organised into sectors and tracks on the platters. The heads move to the specific track and sector to read the required data. The platters spin at a high speed. The rotation, combined with the movement of the magnetic heads, allows for efficient data reading (usually at 5400 rpm or 7200 rpm)., Optical pros/cons - Lightweight, cheap, easy to distribute, easy to scratch/break, low capacity, How is optical memory read? - A laser beam is directed onto the surface of the optical disk. The data on an optical disk is stored as pits and lands. When the laser beam encounters these variations, it reflects differently. As the laser beam hits a flat area, it reflects toward a photoelectric cell. The reflected light is then detected by a sensor. A photodetector detects the variations in reflection. The sensor converts the reflected light into electrical signals. Electrical signals are then translated into binary code, representing the data stored on the disk. The optical disk spins while the laser reads, allowing for a continuous flow of data., Solid state pros/cons - Fastest read/write speed, more durable, lighter, quieter, expensive, How is solid state memory read? - A SSD stores data in memory cells, typically using NAND flash memory technology. Each memory cell contains transistors and gates. The state of these transistors (on or off) determines the binary data. Unlike traditional hard disk drives, SSDs have no moving parts, so this contributes to faster data access. During the read process, electrical voltages are sent through the memory cells. The state of the transistors determines the data stored. The SSD controller manages data flow and communication between the computer and the memory cells., Cloud storage - Refers to being able to store our data remotely (on physical devices) which can be accessed via the internet (or 3rd party providers), Embedded systems - Small computer systems built into a larger device, that performs specific functions, Software - Refers to programs that can be downloaded or installed onto a computer system, Operating system - Main system software each computer system requires, used to allow the hardware and software to communicate with each other by providing a user interface (UI) to the user to interact with the system, What does the OS manage - Memory, Input/Output devices, Security, Processor, Applications, System software - Manages the hardware and software of the computer system, Application software - Software used by the end user to perform tasks, Pros HLL - Easier to understand/debug/read, code can be transported across platforms, Cons HLL - Must be translated so processing takes longer, Pros LLL - Can be directly executed by the processor, Cons LLL - More difficult to learn, machine dependent, Characteristics of an embedded system - Less processing power, smaller amounts of memory, more ROM than RAM, no secondary storage, Pros cloud storage - Accessible on all device with internet access, work from home which increases productivity, collaboration and reduces cost, cheaper over the long run, Cons cloud storage - No internet no access, burn fossil fuel for 24/7 electricity, data privacy issues, you don’t know where your data is stored, Why is cloud storage becoming more viable? - More people have access to internet, increased mobile phone availability, companies build their business model on cloud storage, better network security,

3.4 Computer systems

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