Name: Unit 2 – Computer Structure Define and Explain
The Control Unit o Controls the other parts of the processor o Ensures instructions carried out in the Correct order Arithmetic Logic Unit o Carries out all calculations o Makes decisions based on logic Registers o Temporary memory locations in the Processor o Hold data being processed o Instructions to be executed o Addresses to be accessed Data Bus o Used to transfer from memory to Processor and devices o Bi-directional o Increasing size increases the amount of Memory transferred at one time Address Bus o Used to transfer address information From processor to memory and devices o Width determines number of storage Locations which can be addressed o Has no affect on performance Control Bus Lines o Read o Write o Interrupt o Non-Maskable Interrupt o Reset o Clock
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Read o CU gives Memory Address Register The location to read o CU activates Read Line o Data released onto data bus o Copy placed in Memory Data Register Write o CU provides MAR address to write to o CU provides MDR with value to write o CU activates the write line o Contents transferred to storage location Clock o Keeps events in the processor Synchronised Interrupt o Signal to the processor interrupting Current task o Can ignore them as maybe unimportant Non-Maskable Interrupt o Same as interrupt o But it can’t be ignored! Reset o Returns system to initial state Addressability o Each item in memory saved in storage loc. o Each location has unique address o Each location can hold a word o (word is the size of data bus) o how much data processor can handle in one operation o Calculated by o Storage locations ^ 2 * word size Registers o Storage locations within processor o 1 nanosecond access time Cache o Processor checks this first o Holds most used instructions o Very fast access / expensive
Main Memory o RAM o ROM Comparing Performance Clock Speed o Pulses regulate and co-ordinate activities In the processor o Gives indication of performance o Should not be over emphasized o Other factors also important o i.e. data bus size MIPS Millions of Instructions per second o Measures instructions that can be Processed in a second o Does not take into consideration the size And complexity of instructions Flops Floating Point Operations per second o How many FPO can be carried out per sec o More reliable than MIPS o Clearly definable as different instruction Use more clock cycles o Other factors also important Application Based Tests o Bench Mark Tests o Award scores for performance in package o Reasonable indicators of how it will perform Factors affecting System performance Data Bus Width o Width indicates how many bits that can Be transferred to and from memory Cache Memory o Sits between processor and main memory o Fast acting static RAM o Holds copies commonly used instructions o Get them quicker from Cache Data Transfer Rate of Peripherals o Peripherals operate slower than processor o Can slow down processing
o Having faster drives with faster data Transfer rates improves performance Other factors o Adding more RAM o More processors o Increasing amount of VRAM o Increasing clock speed o Adding more main memory Current trends in Computer Hardware o Increasing Clock Speeds o Increasing Memory o Increasing Backing Storage Capacity Mark in how well you think you are coping with each section Discuss any areas which are problematic with your teacher Read up on these sections FIRST when you are studying!