CPU architecture

CPU architecture

1. Embedded system

2. Embedded systems

   • computers built into other devices
     • dishwashers,microwaves and tv's
   • often used as control systems
     • they monitor and control machinery in order to achive a desired result
   • they are dedicated to a single task

3. cpu

   • central processing unit
     • processes all the data and instructions
     • the power & effeciency
       • depends on clock speed, number of cores andcache size
         • clock speed
           • Higher the clock speed the more instructions can be carried out per second.
         • number of cores
           • each core in a cpu can independently process data. the more cores the more instructions can be carried out at a time
   • the brain of the computer system
   • architecture
     • harvard
     • von neuman
       • describes a system where the CU runs programs stored in momory

4. CU

   • control unit
     • overall control of the cpu
       • main job
         • fetch, decode and execute the program instructions
       • controls the flow of data in the cpu

5. ALU

   • arithmetic logic unit
     • does all the calculations
       • addition, subtraction, multiplication and division
     • performs logic operations
       • and, or, not and binary shifts

6. the cache

   • very fast memory in the cpu
     • slower than the memory but faster than the RAM
   • stores regularly used data
     • for quick access by the cpu
     • it checks cache first when the cpu requests data
   • low capacity but are expencive compared to ram
   • three different levels
     • l1
       • quickest of the levels but lowest capacity
     • l2
       • slower than l1 but has a bigger capacity
     • l3
       • slower than l2 but has a bigger capacity

7. fetch-execute cycle

   • fetch instruction
     • copy memory address from the program counter(pc)to the memory address register (MAR)
   • decode instruction
     • the instruction in the memory data register (MDR) is decode by the control unit (CU)
   • execute instruction
     • the instruction is performed.this could be: load data from memory, write data to memory, do a calculation or logic operation (using the ALU(arithmetic logic unit)

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