Guide to Determine Opcode, Operand, Bytes, Addressing mode, Machine cycles, States, Time required

Opcode and Operand: 

Simply, the instructions (i.e. ADD, ADI, STA, LDA, MOV, MVI, etc) are Opcode.

And the data, memory location and registers are Operand.

How to determine number of bytes of instructions:

- Each Opcode takes 1 byte

- data takes 1 byte

- memory location takes 2 bytes

Note: Registers don't take any bytes.

Addressing Mode:

- Indirect Addressing Mode:

ADD M, SUB M, ANA M, ORA M, XRA M, MOV B,M etc

- Direct Addressing Mode:

STA, LDA, IN, OUT, etc

- Register Addressing Mode:

ADD 'any register', SUB 'any register', XRA 'any register', ORA 'any register', ANA 'any register', etc

- Immediate Addressing Mode:

MVI, ADI, XRI, ORI, ANI, LXI, etc

- Implicit Addressing Mode:

CMA, HLT, etc

How many T-states are required to execute:

- Each Opcode takes 4 T-states (i.e. for OPCODE FETCH)
- Data takes 3 T-states (i.e. for MEMORY READ)
- Memory location takes 9 T-states (i.e. for MEMORY READ or MEMORY WRITE)
- M (memory location content) takes 3 T-states

Note: Registers don't take any T-states

How many Machines Cycles are required:

- Each Opcode takes 1 Machines Cycles (i.e. for OPCODE FETCH)
- Data takes 1 Machines Cycles (i.e. for MEMORY READ)
- Memory location takes 3 Machines Cycles (i.e. for MEMORY READ or MEMORY WRITE)
- M (memory location content) takes 1 Machines Cycles

Note: Registers don't take any Machines Cycles

How to determine Time Required to execute:

- If frequency ( f ) is given then,

T  =  ( ( 1 / f ) * T-states )

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