computer science

computer science

1. what is a computer system

   • a computer system is able to take in inputs, process them and output them
     • it does this through a variety of different hardware and software.
       • a computer system is made up of the CPU, memory and other parts, e.g. a GPU
     • the output is sometimes stored

2. embedded systems

   • an embedded system is normally built into a piece of machinery or device
     • it is designed to provide very limited specific functions (one or two)
   • it mostly consists of a small microprocessor that provides similar functions as the CPU
   • manufacturers use embedded systems for a number of reasons
     • they allow the device to be programmed to automatically perform one or a small number of functions
     • they can reduce the size of the machinery or device. if a larger processor performing many functions is used, it would mean the device may need to be larger is size to accommodate this
     • they can reduce the cost of the machinery or device. if a larger processor is used, most of the functionality would be wasted as only a small number of tasks are required. therefore by removing this, the cost of manufacture can be reduced

3. components of a CPU

   • the CPU is made up of a number of component parts
     • ALU- arithmetic logic unit- it carries out all the arithmetic and logic operations.
     • ACC- accumulator- the register where the intermediate arithmetic and logic results are stored.
     • CU- control unit- responsible for directing the flow of all inputs and outputs to the CPU
     • MAR- memory address register- holds the address location of the next piece of data that is to be fetched into the CPU , or the address where a piece of data will be sent to be stored
     • MDR- memory data register-holds the actual dat that is being fetched into the CPU , or the data that is being sent to be stored in the computers memory.
     • PC- program counter- register that holds the address of the next instruction that is to be carried out.
     • cache- small section of memory that is built into the CPU. it stores most commonly used instructions and dat to allow quick and easy access to them