fetch-execute cycle. memory read operation read from memory

Download Fetch-Execute cycle. Memory Read operation Read from memory

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Fetch-Execute cycle Slide 2 Memory Read operation Read from memory Slide 3 Main Memory MAR MDR Control Unit ALU Other registers Electronic Clock Clock pulses Address bus Data bus Control bus PC 1 The Program Counter (PC) holds the address of the next instruction Slide 4 Main Memory MAR MDR Control Unit ALU Other registers Electronic Clock Clock pulses Address bus Data bus Control bus PC 1 The contents of the PC are copied to the Memory Address Register (MAR) 10110111 Slide 5 Main Memory MAR MDR Control Unit ALU Other registers Electronic Clock Clock pulses Address bus Data bus Control bus PC 1 Memory address to be accessed is placed onto the address bus 10110111 Slide 6 Main Memory MAR MDR Control Unit ALU Other registers Electronic Clock Clock pulses Address bus Data bus Control bus PC 1 The control bus sends a read signal >>read>> Slide 7 Main Memory MAR MDR Control Unit ALU Other registers Electronic Clock Clock pulses Address bus Data bus Control bus PC 1 The contents of the memory location are passed along the data bus to the Memory Data Register (MDR) 01010111 Slide 8 Main Memory MAR MDR Control Unit ALU Other registers Electronic Clock Clock pulses Address bus Data bus Control bus PC 1 The PC is incremented ready for the next instruction 2 Slide 9 Memory Write operation Write to memory Slide 10 Main Memory MAR MDR Control Unit ALU Other registers Electronic Clock Clock pulses Address bus Data bus Control bus PC 2 Data is placed onto the data bus 1110011 Slide 11 Main Memory MAR MDR Control Unit ALU Other registers Electronic Clock Clock pulses Address bus Data bus Control bus PC 2 Memory address to be written to is placed onto the address bus 11110010 Slide 12 Main Memory MAR MDR Control Unit ALU Other registers Electronic Clock Clock pulses Address bus Data bus Control bus PC 2 A write signal is sent along the control bus >>write>> Slide 13 Main Memory MAR MDR Control Unit ALU Other registers Electronic Clock Clock pulses Address bus Data bus Control bus PC 2 The data is transferred to the destination in memory 10111110 Slide 14 Main Memory MAR MDR Control Unit ALU Other registers Electronic Clock Clock pulses Address bus Data bus Control bus PC 2 The PC is incremented 3

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