Question

Write an assembly language program for 8051 microcontroller to find the sum of the following

series,

1, -2, +3, -4, +5, -6,..., up to 100 terms.

Store lower byte in R0 and higher byte in R1.

Answer 1

                  // In the sereis all even numbers are negive and odd numbers are positive
                
                  ORG 000h
                  MOV R1,#64H       //Enter the final number of Series
                  MOV A,#00H        //Initilize the Accumulator with zero
         AGAIN:   MOV R0,R1         // Copy the contenets of R1 to R0
                  RRC R0            //Rotate R0 once to right if carry is zero then it is even number else odd number
                  JNC EVEN_Number   //if carry is not set then even nuber and jump to EVEN_Number location
                  JC ODD_Number     //if carry is set then odd nuber and jump to ODD_Number location
   EVEN_Number:   CPL R0            //ones complement R0
                  ADD R0, #01H      //Add one to complemented number
   ODD_Number:    ADD A,R0          //Add Ro to Acummulator
                  DJNZ R1, AGAIN    //Decrement R1 if not zero jumber AGAIN location else continue
                  MOV R2,A          //Move the final ansuer from Acummulator to R2
                  END               // End the program