Hardware

• The CPU is the brain of the computer.
• Virtual memory is a memory management technique that allows a computer to compensate for physical memory shortages by temporarily transferring data from RAM to disk storage.
• EEPROM (electrically erasable programmable read-only memory) is a type of ROM chip that can be electrically erased and reprogrammed multiple times.
• RAM, or random access memory is a type of primary storage used to store temporary data currently in use by the computer.
• Secondary storage is not directly accessed by the CPU.
• Optical discs such as CDs and DVDs are used for storing and transporting digital media.
• ROM, or read-only memory is a type of primary storage that stores permanent data on how the computer starts up and loads the operating system.
• SSD, or solid-state disks is known as a flash memory storing data by controlling the flow of electrons.
• USB stands for Universal Serial Bus
• HDD uses magnetic disks and read and write heads to store and use data. Magnetic charges created on the surfacegive gives 1 of 2 directions representing binary values 0 or 1.
• Optical disks use reflective light to read data. The optical disk surface is covered with pits and heads which causes reflection.
• Examples of internal secondary storage are SSD and HDD.
• Examples of external secondary storage are USB, CD, and DVD.
• CPU has an ALU (Arithmetic Logic Unit), CU (Control Unit), and Registers.
• Examples of SSD are USB stick and memory card.
• Examples of magnetic disks are hard drive and tape drive.
• Examples of optical disks are DVD and Blu Ray.
• CPU uses a fetch-decode-execute cycle to perform its role.
• Fetch is to gain the next instruction and associated data from the main memory.
• Decode is to interpret the fetched instructions into machine language.
• Execute is to perform the instructions.
• Registers: program counter, memory address register, memory data register, current instruction register, and accumulator.
• The cache acts as an intermediary between the processor and the main memory. As programs are executing, the cache holds commonly used programs.
• Address bus passes address from the processor to the main memory. It is one-directional and all data is returned on the data bus.
• Data bus transfers data to and from the main memory or secondary storage, or into or out of the processor.
• System bus shares data throughout the computer and between devices.
• Control bus carries control signals from the processor to other components in the computer.
• Virtual memory is used when the RAM is full and some programs have to be removed from RAM to make room for new programs.
• RAM is volatile, when the computer is switched off the data is lost.
• Cache is an alternative to store data, fulfil user's request to open something, and to reduce wait time.
• Roles of CPU: Carries out instructions, processes data, retrieves data from main memory, stores data to main memory once executed.
• Secondary storage is used for back ups providing long-term storage for data and programs.
• Primary storage is temporary storage and is internal hardware.
• Secondary storage has a much larger storage capacity compared to primary storage.
• HDD has a large storage capacity, inexpensive per gigabyte, and can store a wide range of data but has a slower access time.
• SSD has a large storage capacity and has faster data access time but has a higher cost per gigabyte.
• Magnetic storage has a large capacity and has a low cost per gigabyte but is slow in access time and vulnerable to physical damage.
• Optical storage has faster access time than magnetic and is fairy portable but can easily be damaged.
• SSD replace traditional HDD in computers and performs the same functions but with increased speed, more durability, and less power consumption.
• LED is short for light emitting diodes