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Program to exchange the contents of two memory locations

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Statement: Exchange the contents of memory locations 2000H and 2001H.

Example: 

Initially,
(2000H) = 34H
(2001H) = 20H

After exchanging,
(2000H) = 20H
(2001H) = 34H

Program 1 using direct addressing instructions:

LDA 2000H               ; Get the contents of location 2000H into accumulator
MOV B, A                  ; Move the contents of accumulator into register B
LDA 2001H                ; Get the contents of location 2001H into accumulator
STA 2000H                 ; Store the contents of accumulator into location 2000H
MOV A, B                  ; Move the contents of register B into accumulator
STA 2001H                 ; Store the contents of accumulator into location 2001H
HLT                             ; Terminate program execution

Program 2 using indirect addressing instructions:

LXI H, 2000H               ; HL points to location 2000H
LXI D, 2001H               ; DE points to location 2001H
MOV B, M                    ; Get the contents of location 2000H into register B
LDAX D                        ; Get the contents of location 2001H into accumulator
MOV M, A                    ; Move the contents of accumulator into location 2000H
MOV A, B                     ; Move the contents of register B into accumulator
STAX D                         ; Store the contents of accumulator into loaction 2001H
HLT                                ; Terminate program execution

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