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The working of 8085 microprocessor can best be understood by considering the timing diagrams of its few instructions.
The working of 8085 microprocessor can best be understood by considering the timing diagrams of its few instructions.
The graphical representation depicting the necessary steps carried out in a machine cycle is known as Timing Diagram.
The graphical representation depicting the necessary steps carried out in a machine cycle is known as Timing Diagram.
The total time required for the execution of an instruction is the time required to fetch and execute an instruction.
The total time required for the execution of an instruction is the time required to fetch and execute an instruction.
Instruction Cycle = Instruction fetch + Instruction execution
Instruction Cycle = Instruction fetch + Instruction execution
The instruction cycle may be of one, two or three bytes.
The instruction cycle may be of one, two or three bytes.
During the fetch cycle, an instruction of the program (op code) is extracted from the memory locations and copied in the instruction register (IR) of C.P.U.
During the fetch cycle, an instruction of the program (op code) is extracted from the memory locations and copied in the instruction register (IR) of C.P.U.
The op code of the instruction copied in the instruction register (IR) is decoded during the execution cycle to perform the specific activities.
The op code of the instruction copied in the instruction register (IR) is decoded during the execution cycle to perform the specific activities.
It may further be mentioned that an instruction cycle may take one to five machine cycles.
It may further be mentioned that an instruction cycle may take one to five machine cycles.
Generally, first machine cycle known as op code fetch cycle, has either four or six T-states and the remaining machine cycles called execution cycles, have two or three T-states.
Generally, first machine cycle known as op code fetch cycle, has either four or six T-states and the remaining machine cycles called execution cycles, have two or three T-states.
A T-state represents one clock cycle.
A T-state represents one clock cycle.
The NOP is the shortest instruction which takes only one machine cycle with four T-states.
The NOP is the shortest instruction which takes only one machine cycle with four T-states.
However, the CALL is the longest instruction which takes five machine cycles with 18 T states.
However, the CALL is the longest instruction which takes five machine cycles with 18 T states.
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