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8085 Program to convert a two-digit BCD to binary
In this program we will see how to convert BCD numbers to binary equivalent.
Problem Statement
A BCD number is stored at location 802BH. Convert the number into its binary equivalent andstore it to the memory location 802CH.
Discussion
In this problem we are taking a BCD number from the memory and converting it to its binaryequivalent. At first we are cutting each nibble of the input. So ifthe input is 52 (0101 0010) then we can simply cut it by masking the number by 0FH and F0H. When the Higher order nibble is cut, thenrotate it to the left four times to transfer it to lower nibble.
Now simply multiply the numbers by using decimal adjust method to get final decimal result.
Input
| Address | Data |
|---|---|
| . . . | . . . |
| 802B | 52 |
| . . . | . . . |
Flow Diagram
Program
| Address | HEX Codes | Labels | Mnemonics | Comments |
|---|---|---|---|---|
| 8000 | 31, FF, 80 | LXI SP,80FFH | Initialize stack pointer | |
| 8003 | 21, 2B, 80 | LXI H, 802BH | Pointer to the IN-BUFFER | |
| 8006 | 01, 2C, 80 | LXI B, 802CH | Pointer to the OUT-BUFFER | |
| 8009 | 7E | MOV A, M | Move the contents of 802BH to A | |
| 800A | CD, 0F, 80 | CALL BCDBIN | Subroutine to convert a BCD number to HEX | |
| 800D | 02 | STAX B | Store Acc to memory location pointed by BC | |
| 800E | 76 | HLT | Terminate the program | |
| 800F | C5 | BCDBIN | PUSH B | Saving B |
| 8010 | 47 | MOV B, A | Copy A to B | |
| 8011 | E6, 0F | ANI 0FH | Mask of the most significant four bits | |
| 8013 | 4F | MOV C, A | Copy A to C | |
| 8014 | 78 | MOV A, B | Copy B to A | |
| 8015 | E6, F0 | ANI F0H | Mask of the least significant four bits | |
| 8017 | 0F | RRC | Rotate accumulator right 4 times | |
| 8018 | 0F | RRC | ||
| 8019 | 0F | RRC | ||
| 801A | 0F | RRC | ||
| 801B | 57 | MOV D, A | Load the count value to the Reg. D | |
| 801C | AF | XRA A | Clear the contents of the accumulator | |
| 801D | 1E, 0A | MVI E, 0AH | Initialize Reg. E with 0AH | |
| 801F | 83 | SUM | ADD E | Add the contents of Reg. E to A |
| 8020 | 15 | DCR D | Decrement the count by 1 until 0 is reached | |
| 8021 | C2, 1F, 80 | JNZ SUM | ||
| 8024 | 81 | ADD C | Add the contents of Reg. C to A | |
| 8025 | C1 | POP B | Restoring B | |
| 8026 | C9 | RET | Returning control to the calling program |
Output
| Address | Data |
|---|---|
| . . . | . . . |
| 802C | 34 |
| . . . | . . . |
Updated on: 30-Jul-2019
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