Logical Instructions in 8085 Microprocessor (Solved Problem 2)

Summary

In this educational video, the presenter continues a series on logical instructions in 8085 assembly language programming. The session focuses on a problem where data from memory location X is multiplied by four and stored at location Y. The solution involves using the RLC instruction twice to achieve the multiplication. The process is demonstrated with a practical example, including writing the program, setting memory locations, and executing it in an emulator. The result is a clear explanation of how to manipulate data in assembly language.

Takeaways

• 📘 The session focuses on solving problems based on logical group of instructions in 8085 assembly language.
• 🔢 The specific problem involves taking data from memory location X, multiplying it by four, and storing the result at memory location Y.
• 🕊 The RLC (Rotate Left Circular) instruction is used for multiplying the accumulator content by two, which can be executed twice to achieve a multiplication by four.
• 📚 The ldax instruction is utilized to load data from memory location X into the accumulator.
• 🔄 Executing the RLC instruction twice effectively shifts the bits in the accumulator left by two positions, doubling the value twice (2x2=4).
• 📝 After the multiplication, the sty instruction is used to store the result back into memory location Y.
• 🏁 The HLT (Halt) instruction signifies the end of the program, signaling to the microprocessor that the program has concluded.
• 💾 The example uses memory locations 440 for input data (X) and 4410 for output data (Y), with the input data being '02' in hexadecimal.
• 🔧 The emulator is used to assemble, load, and execute the program, demonstrating the process of taking input, performing operations, and producing output.
• 📈 The input data '02' when multiplied by four results in '08', which is the expected output stored in memory location 4410 after program execution.
• 🎓 The session concludes with a recap of the covered topic and a teaser for the next session, which will involve more logical instructions.

Q & A

What is the main topic of the session?

The main topic of the session is to solve a problem on logical group of instructions using 8085 assembly language.

What is the specific problem that the session aims to solve?

The session aims to solve a problem where data from memory location X is taken, multiplied by four, and then stored at memory location Y.

What is the role of the RLC instruction in the 8085 assembly language in this context?

The RLC (Rotate Left Circular) instruction is used to multiply the data in the accumulator by two. Executing it twice will multiply the data by four.

How does the RLC instruction work in the context of this problem?

The RLC instruction rotates the content of the accumulator to the left by one bit. Executing it twice effectively multiplies the data by 2 x 2, which is 4.

What data transfer instruction is used to load data from memory location X into the accumulator?

The data transfer instruction 'ldax' is used to load data from memory location X into the accumulator.

What data transfer instruction is used to store the result in memory location Y?

The 'sty' instruction is used to store the result in memory location Y.

What is the purpose of the HLT instruction in the program?

The HLT (Halt) instruction is used to signal the microprocessor that the program has ended.

What is the input data stored at memory location 4400 in the example provided?

The input data stored at memory location 4400 is 02 in hexadecimal, which is 6 in decimal.

What is the expected output data after the program execution in the example?

The expected output data after the program execution is 08 in hexadecimal, which is 8 in decimal, as the input data is multiplied by 4.

How does the bit sequence change after executing the RLC instruction twice on the input data 02?

After executing the RLC instruction twice on the input data 02, the bit sequence changes from 0010 to 1000, which is the binary representation of 8.

What is the significance of the emulator in this session?

The emulator is used to assemble, load, and run the 8085 assembly language program to verify the correctness of the solution.