Topic 4 - Hardware and Software

Topic 4 - Hardware and Software

1. CPU

   • Registers
     • Program Counter (PC)
       • Counts which instruction the computer is currently running
     • Memory Address Register (MAR)
       • Stores where the data needed is located or where it needs to go
     • Current Instruction Register (CIR)
       • Stores the current instruction the CPU is running
     • Accumulator (ACC)
       • Stores the total results from calculation
     • Memory Data Register (MDR)
       • Acts as a buffer to store data before it is executed
     • A small location of memory in the CPU that stores data
   • Buses
     • Data Bus
       • Transmits the data between the CPU and memory
     • Control Bus
       • Sends and receives information between other parts in the computer
     • Address Bus
       • Finds where the data is
   • Clock Speed
     • How many times the fetch-decode-execute cycle is executed a second
     • It is impacted by the number cores in the CPU
       • The greater the number of cores the more actions can be completed each second
     • Measured in hertz
       • Most modern CPUs have a clock speed measured in gigahertz

2. Memory

   • RAM
     • Programs, applications and data that is currently in use are stored on
     • Volatile memory
       • Wiped when power is cut off
   • ROM
     • Non-Volatile
       • Can't be rewritten
     • Stores essential things for the computer like the boot sequence
   • Secondary Storage
     • Long term storage that is non-volatile and not wiped when the
     • Types of secondary storage
       • Magnetic
         • Often used to back up important files from the HDD and archiving files
       • Solid State
         • Similar to a HDD but much faster but due to this they are much more expensive than a HDD
       • Optical
         • Burnt on to grooves on a disk to store data on discs
       • USB Thumb Drive
         • A small portable HDD used for transferring data
       • Flash Memory Cards
         • A small card that stores a few GB of data often used in mobile phones
       • Cloud Storage
         • Online storage where you pay to use a part of someone else's secondary storage connected via the internet
   • Cache
     • A small amount of memory near the CPU closer than the RAM
       • Used to access actions that the CPU is likely to use often

3. Software