Programming examples of 6800

Now, in this section, we will see how we can use the Motorola M6800 Microprocessor to add multi-Byte numbers.

• AddingMulti-Byte Number

In this example, we are using 4-Byte numbers (56 2F 7A 89)₁₆ and (21 FB A9 AF)₁₆

In the memory, at first, we are storing the Byte counts, and then the numbers (from least significant Bytes to Most significant Bytes) in different segments. So after storing the data, the memory structure will be looking like this

Now, we are writing a program to add these two 4-Byte number and store the result at location 5090H onwards.

Program

      CLC
      LDX#$5050

LOOP: LDAA $0, X
      ADCA $20, X
      STAA $40, X


      INX
      DEC$5000
      BNELOOP

      CLR$40, X
      BCCDONE
      INC$40, X
DONE: WAI

Output

• BlockExchange Program

Now we will see how we can use the M6800 Microprocessor to Exchange the contents of each element from two different blocks.

The number of items in each block is given at location 5000H, and the blocks are at position 5050H and 5070H.

So before swapping the items in the memory is looking like this

Now, we are writing a program to exchange the block contents.

Program

      LDX#$5050
     
LOOP: LDAA 0, X
      LDAB $20 X

      STAA $20, X
      STAB $0, X

      INX
      DEC$5000
      BNELOOP
      WAI

Output

• Move block of data

Let us see another example of the M6800 Microprocessor Program. Here the program is to move a block of data to another location. There is one assumption, there is sufficient distance between source and destination. So blocks are not-overlapping. Basically, the block movement is not exactly moving, itis copying the data to other locations.

The number of items in the block is given at location 5000H, and the block is located at position 5050H.

So before movement, the items in the memory is looking like this.

Now, we are writing a program to move the block contents to other locations.

Program

LDX#$5050
LOOP: LDAA 0, X
STAA $20, X
INX
DEC$5000
BNELOOP

      WAI

Output

George John

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Updated on: 27-Jun-2020

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