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2-Digit BCD to binary conversion

Published on Nov 18 2009 // Code conversion

Statement: Convert a 2-digit BCD number stored at memory address 2200H into its binary equivalent number and store the result in a memory location 2300H.

Sample problem 1:

(2200H) = 67H

(2300H) = 6 x OAH + 7 = 3CH + 7 = 43H

Source program :

  • LDA 2200H : Get the BCD number
  • MOV B, A : Save it
  • ANI OFH : Mask most significant four bits
  • MOV C, A : Save unpacked BCDI in C register
  • MOV A, B : Get BCD again
  • ANI FOH : Mask least significant four bits
  • RRC : Convert most significant four bits into unpacked BCD2
  • RRC
  • RRC
  • RRC
  • MOV B, A : Save unpacked BCD2 in B register
  • XRA A : Clear accumulator (sum = 0)
  • MVI D, 0AH : Set D as a multiplier of 10
  • Sum:   ADD D : Add 10 until (B) = 0
  • DCR B : Decrement BCD2 by one
  • JNZ SUM : Is multiplication complete? i if not, go back and add again
  • ADD C : Add BCD1
  • STA 2300H : Store the result
  • HLT : Terminate program execution

Flowchart for program

54-2-Digit BCD to binary conversion 

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