Computing - Hardware & Communication

Computing - Hardware & Communication

1. Processor: Every computer has a CPU (Central processing unit) the brain of the computer, it refers to that part of the processor that processes the data and instructions.

   • The main parts of CPU:
     • ALU (Arithmetic & logic unit) which performs calculations on the data.
     • The control unit - Which controls all operations outside the computer.
     • Memory storage, a register is a place where a single item of data can be stored.
   • All computers have input and output devices, programs that run are stored in the memory.
   • RAM (Random access memory) - is the type of memory used for temporarily storing programs and data.
     • Memory consists of large number of store locations which data can be stored, store locations are identified by addresses.
       • Data is moved along a path called a data bus.
         • When data is saved to memory, the address of the store location at which it is stored is also sent, the address of data travels along a address bus.
         • The control unit send and recieves signals from all parts of the computer which make sure all the processes take place at the right time. These signal travel along a control bus.

2. Bits Bytes & Words:

   • Computer memory consists of large number of two state devices the digit 1 or 0.
   • 8 bits = 1 byte

3. Memory:

   • There are two types of storage: primary storage (memory) & secondary storage (backing storage)
     • Primary Storage:
       • RAM is volatile - the data is lost when switched off.
       • ROM (Read only memory) is used for storing permanent data, it is non volatile.
       • The ROM stores the programs that control embedded systems.
       • RAM cache: is a memory chip used to temporarily store data & is used to improve speed of a computer when running a program. It can supply data to the CPU faster than normal RAM.
         • Disc Cache: is an area of memory used to store data when it is input from a disc. e.g. Recently accessed data would be stored in the cache as it is easier to access.
     • Secondary Storage:
       • Speed is less important than large storage capability.
         • Magnetic tape
         • Magnetic disc
         • Optical disc.
         • Flash memory

4. Analogue & Digital:

   • Digital can only be distinct values.
   • Analogue can vary continuously within a range of values.