The Processor

The processor is essentially the brain of the computer that controls everything that goes on. Processors can be found in a lot of everyday items such as microwaves, phone and washing machines. The ALU (arithmetic and logic unit),part of the processor, carries out the calculations and logical operations such as AND,OR,NOT. Each one of the memory address locations must be unique so they are easy to find. The control unit is the processor works with the fetching,decoding and executing of instructions that can be as simple as changing a page. The Registers act as temporary storage locations like memory but are much faster. The MAR is the memory address register which is used to keep the address of a memory location where data is kept. If you want to write data the MAR has to get the address of where it needs to go and the MDR (memory data register) which is the data that is being written. Once done the write line on the control bus activates and the data in MDR is sent to the address specified in the MAR, along the data bus. For reading the MAR needs the address of where the data is located and once that is achieved the read line on the control bus is activated. After doing so the address bus finds where the data is and the data is sent back through the data bus to the MDR. The data is then decoded and executed. These read and write operations are used to load instructions and are found in programs as there are lots of instructions within them. This is known as the fetch and execute cycle. The control bus always has 4 functions – read, write, clock and interrupt. Read tells the memory the data is to be sent to the processor from a specified memory location. Write tells the memory that the data is to be sent and stored to a specified memory location. Clock regulates the speed the information travels at by generating a constant pulse. Interrupt ensures that if something interrupts the current task the task will be put on hold and stored in a temporary memory location called the stack and will be returned to once the interruption is complete. The interruption could be caused by things being put into the computer such as USB or other programs being loaded. 

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