Question

Calculate the time required to execute the entire instruction cycle if two machine codes, 0011 1110 and 0011 0010, are stored in memory locations 2000H and 2001H, respectively.

If the clock frequency is 2 MHz, the first machine code represents opcode to load data byte in the accumulator and the second code represents data to be loaded in the accumulator.

1. 1.5 μs
2. 0.5 μs
3. 3.5 μs
4. 2.5 μs

Answer 1

Correct Answer - Option 3 : 3.5 μs

Explanation:

Here two machine codes are being executed:

1. Opcode Fetch

2. Data to be uploaded in the accumulator

We can use the following instruction set:

MVI A, data

1 This is a 2-byte instruction.

2 Immediate addressing mode is used.

3 Total machine cycle = Opcode Fetch + Memory Read

4 Total machine cycle = 4T + 3T = 7T

Where T = T-states.

Calculation:

f = 2 MHz

\(T=\frac{1}{f}=\frac{1}{2}=0.5 \ μ s\)

Total machine cycle = 7T

Total machine cycle = 7 × 0.5 = 3.5 μs