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presentation on timing diagram

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this presentation will tell you about opcode fetch ,memory read &memory write

this presentation will tell you about opcode fetch ,memory read &memory write

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  • 1.  
  • 2.
    • An instruction is a command given to the computer to perform a specified operation on a given data.
    • To perform a particular task a programmer writes a sequence of instructions called a program.
  • 3.
    • The CPU fetches one instruction from the memory at a time and execute it . It executes all the instructions of a program one by one to produce to the final result .
    • Instruction cycle consist of fetch and execute cycle.
    • In fetch cycle a CPU fetches opcode from the memory.
    • Specific operation in an instruction constitute an execute cycle.
    • IC=FC+EC
  • 4. T3 T1 T2 T2 T1 T4 T3 Instruction Cycle Opcode Fetch Execute
  • 5.
    • The necessary steps carried out to perform the operation of accessing either memory or I/O device, constitute a machine cycle.
    • Necessary steps carried out to perform a fetch, a read or write operation constitute a machine cycle.
    • One basic operation such as opcode fetch, memory read, memory write ,I/O read , or I/O write.
    • Instruction cycle consist of several machine cycle.
  • 6.
    • One subdivision of an operation performed in one clock cycle is called a state or T-state.
    • The subdivisions are internal states synchronized with the system clock .
    • So one clock cycle of the system is referred to as a state.
  • 7. M1 M2 Next instruction cycle T3 T1 T2 T2 T1 T4 T3 Instruction Cycle Opcode Fetch Execute
  • 8.
    • The necessary steps which are carried out in a machine cycle can be represented graphically . Such a representation is called timing diagram .
    • Timing diagram:
      • Opcode fetch
      • Memory read
      • Memory write
      • I/O Read
      • I/O write
  • 9.
    • In a fetch cycle the microprocessor fetches the opcode of an instruction from the memory
  • 10. T1 T2 T3 T4
  • 11.
    • In a memory read cycle the microprocessor reads the content of a memory location.
    • The content is then placed either in the accumulator or any other register of the CPU.
  • 12.  
  • 13.
    • In a memory write cycle the CPU sends data from the accumulator or any other register to the memory.
  • 14.  
  • 15.  

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