To transfer 5 bytes of data from a location starting at 2054H to a location starting at 2060H

Explanation

1. Purpose

This 8085 assembly program copies a block of 5 bytes of data from a source memory block starting at 2054H to a destination block starting at 2060H.

2. Key Concepts

• Pointer-based Indirect Addressing: Using register pairs (HL and DE) to hold memory addresses for reading and writing data.
• Looping with a Counter: Using register C to track remaining iterations, controlled by DCR (Decrement) and JNZ (Jump if Not Zero).
• Accumulator as an Intermediate Buffer: Transferring data from memory to memory via the Accumulator register (A).

3. Code Walkthrough

• Setup / Initialization:

  • LXI H, 2054H & LXI D, 2060H: Load starting addresses into HL (source pointer) and DE (destination pointer).
  • MVI C, 05H: Set the loop counter to 5.

• Loop Body (LOOP):

  • MOV A, M: Reads data from the address pointed to by HL into the Accumulator.
  • STAX D: Writes the byte from the Accumulator into the address pointed to by DE.
  • DCX H: Moves the source pointer backward by 1 byte (Note: It decrements from 2054H to 2050H).
  • INX D: Moves the destination pointer forward by 1 byte (2060H → 2061H...).
  • DCR C: Decrements the counter.
  • JNZ LOOP: If counter C is not zero, repeats the process.

• Termination:

  • HLT: Halts the CPU when all 5 bytes are transferred.

4. Output

The 5 bytes from source locations 2054H down to 2050H are copied into destination locations 2060H through 2064H:

| Source Address | Destination Address | | :--- | :--- | | 2054H | 2060H | | 2053H | 2061H | | 2052H | 2062H | | 2051H | 2063H | | 2050H | 2064H |