Sunday, 12 November 2017

How to Find Subtraction of two 8 bit numbers 8085 Microprocessor

SUBTRACTION OF TWO 8 BIT NUMBERS | How to Find Subtraction of two 8 bit numbers 8085 Microprocessor

     To perform the subtraction of two 8 bit numbers using 8085.
     1. Start the program by loading the first data into Accumulator.
        Move the data to a register (B register).
     2. Get the second data and load into Accumulator.
     3. Subtract the two register contents.
     4. Check for carry.
     5. If carry is present take 2’s complement of Accumulator.
     6. Store the value of borrow in memory location.
     7. Store the difference value (present in Accumulator) to a memory
     8. location and terminate the program.
          MVI C, 00I Initialize C to 00
          LDA 4150     Load the value to Acc.
          MOV B, A    Move the content of Acc to B register.
          LDA 4151     Load the value to Acc.
          SUB B
          JNC LOOP   Jump on no carry.
          CMA           Complement Accumulator contents.
          INR A         Increment value in Accumulator.
          INR C         Increment value in register C
LOOP: STA 4152   Store the value of A-reg to memory address.
          MOV A, C    Move contents of register C to Accumulator.
          STA 4153    Store the value of Accumulator memory address.
          HLT         Terminate the program.
            Input: 06 (4150)
                    02 (4251)
            Output: 04 (4152)
                    01 (4153)
     Thus the program to subtract two 8-bit numbers was executed