TOPIC 1.1 system architecture

TOPIC 1.1 system architecture

1. Cache memory

   • In computing, a cache /kæʃ/ KASH,[1] is a hardware or software component that stores data so future requests for that data can be served faster; the data stored in a cache might be the result of an earlier computation, or the duplicate of data stored elsewhere. A cache hit occurs when the requested data can be found in a cache, while a cache miss occurs when it cannot. Cache hits are served by reading data from the cache, which is faster than recomputing a result or reading from a slower data store; thus, the more requests can be served from the cache, the faster the system performs.

2. FDE Cycle

   • 1. Content of Program Counter (PC) assigned to Memory Address register (MAR)
     • 2. PC incremented by 1 and assigned to PC AT HTE SAME TIME the addressed contents of memory is assigned to the MDR ( memory Data register )
       • 3. Then the contents of MDR is assigned to CIR (current Instruction is decoded and executed.
         • 4. The Instruction is decoded in the ALU where all logical and arithmetic calculations are performed. The results of this are stored in the Accumlator. The instruction is then executed and the cycle starts again.

3. CPU Performance

   • Clock speed
     • Also called clock rate, the speed at which a microprocessor executes instructions. ... The CPU requires a fixed number of clock ticks (or clock cycles) to execute each instruction. The faster the clock, the more instructions the CPU can execute per second. Clock speeds are expressed in megahertz (MHz) or gigahertz ((GHz).
   • Cache Size
     • Cache Size. The size of the cache normally refers actually to the size of the data store, where the memory elements are actually stored. A typical PC level 2 cache is either 256 KB or 512 KB, but can be as small as 64 KB on older machines, or as high as 1 MB or even 2 MB.
   • Number of Cores
     • This total number of logical processors is the number of physical CPUs multiplied by the number of cores per CPU. In the example below we have each physical CPU containing 4 cores. There are 2 physical CPUs on the system so 2 CPUS X 4 cores each CPU = 8 total cores.