Statement: Exchange the contents of memory locations 2000H and 4000H.

Program 1:
LDA 2000H : Get the contents of memory location 2000H into accumulator
MOV B, A : Save the contents into B register
LDA 4000H : Get the contents of memory location 4000Hinto accumulator
STA 2000H  : Store the contents of accumulator at address 2000H
MOV A, B : Get the saved contents back into A register
STA 4000H : Store the contents of accumulator at address 4000H

Program 2:
LXI H 2000H : Initialize HL register pair as a pointer to memory location 2000H.
LXI D 4000H : Initialize DE register pair as a pointer to memory location 4000H.
MOV B, M  : Get the contents of memory location 2000H into B register.
LDAX D : Get the contents of memory location 4000H into A register.
MOV M, A : Store the contents of A register into memory location 2000H.
MOV A, B : Copy the contents of B register into accumulator.
STAX D : Store the contents of A register into memory location 4000H.
HLT : Terminate program execution.