AIM:
To write an 8085 assembly language program that executes the following conversions
- BCD TO BINARY.
- Binary to BCD
- Binary to ASCII
- ASCII to Binary
APPARATUS REQUIRED:
8085 microprocessor kit, Power supply.
ALGORITHM:
BCD TO BINARY:
Step 1: Initialize stack pointer
Step 2: Initialize HL register pair with a source pointer.
Step 2: Initialize BC register pair with a destination pointer.
Step 3: Move contents of memory pointer to accumulator.
Step 4: Call subroutine BCD BIN.
Step 5: Store the content of Accumulator in destination pointer.
Step 6: End of execution.
SUBROUTINE:
- Push the content of BC & DE register pair to stack pointer.
- Logically AND the number 0F with accumulator to get LSB
- Again logically AND the number F0with accumulator and rotate the content to the right four times to get MSB
- Multiply the MSB with 0A and add with LSB
| Memory Location | Machine code | Label | Mnemonics | Comment |
| 4100 | 31,FF,4F | LXI SP, 4FFF | Initialize stack pointer | |
| 4103 | 21, 00, 42 | LXI H, 4200 | Initialize HL register pair with a source pointer | |
| 4106 | 01,00,43 | LXI B 4300 | Load BC register pair with destination pointer | |
| 4109 | 7E | MOV A,M | Move [M] to Accumulator | |
| 410A | CD, 0F,41 | CALL BCD BIN | Call sub routine BCD BIN | |
| 410D | 02 | STAX B | Store the Binary number in the destination location | |
| 410E | 76 | HLT | End of execution |
SUBROUTINE
| Memory Location | Machine code | Label | Mnemonics | Comment |
| 410F | C5 | BCD BIN | PUSH B | Push [B C ] into stack pointer |
| 4110 | D5 | PUSH D | Push [D E] into stack pointer | |
| 4111 | 47 | MOV B,A | Move [A] to B register | |
| 4112 | E6,0F | ANI 0F | And immediate the accumulator with 0F | |
| 4114 | 4F | MOV C,A | Move[A] to C register | |
| 4115 | 78 | MOV A,B | Move[B] to Accumulator | |
| 4116 | E6,F0 | ANI F0 | And immediate accumulator with F0 | |
| 4118 | CA,28,41 | JZ BCD | Jump on zero to BCD loop | |
| 411B | 0F | RRC | Rotate accumulator content to right | |
| 411C | 0F | RRC | Rotate accumulator content to right | |
| 411D | 0F | RRC | Rotate accumulator content to right | |
| 411E | 0F | RRC | Rotate accumulator content to right | |
| 411F | 57 | MOV D,A | Move [A] to D register | |
| 4120 | AF | XRA A | Clear accumulator | |
| 4121 | 1E, 0A | MVI E, 0A | Move 0A to E register | |
| 4123 | 83 | SUM | ADD E | Add E with accumulator content |
| 4124 | 15 | DCR D | Decrement D register. | |
| 4125 | C2,23,41 | JNZ SUM | Jump on no zero to sum | |
| 4128 | 81 | BCD | ADD C | Add C to accumulator |
| 4129 | D1 | POP D | Retrieve the content of D from stack | |
| 412A | C1 | POP B | Retrieve the content of B from stack | |
| 412B | C9 | RET | Return to main program |
b) Binary to BCD:-
Algorithm:
Step 1: Initialize stack pointer
Step 2: Initialize the register pair as memory pointer.
Step 3: Move Binary number to accumulator
Step 4: Call subroutine 1
Step 5:End of the execution
SUBROUTINE 1:
Step 1: Load HL register pair with MP
Step 2: Store 64h in B register.
Step 3: Call subroutine 2.
Step 4: Store 0Ah in B register & call subroutine2
Step 5: Store accumulator contents in next memory location
Step 6: Return to Main program.
SUB ROUTINE 2:
Step 1: Clear Memory location
Step 2: Subtract the B register from accumulator
Step 3: If the subtraction results a carry add B register content with accumulator and increment memory pointer.
Step 4: return to subroutine1
| Memory Location | Machine code | Label | Mnemonics | Comment |
| 4100 | 31,FF,4F | LXI SP, 4FFF | Initialize stack pointer | |
| 4103 | 21, 00, 42 | LXI H,4200 | Initialize HL register pair with a source pointer | |
| 4106 | 7E | MOV A,M | Move [M] to Accumulator | |
| 4107 | CD, 0B,41 | CALL PWRTEN | Call sub routine PWRTEN | |
| 410A | 76 | HLT | End the execution |
Subroutine 1
| Memory Location | Machine code | Label | Mnemonics | Comment |
| 410B | 21,00,43 | PWRTEN | LXIH, 4300 | Load HL register pair with 4300 |
| 410E | 06,64 | MVI B,64 | Move 64h to B register | |
| 4110 | CD,1A,41 | CALL BIN BCD | Call subroutine BIN BCD | |
| 4113 | 06,0A | MVI B,0A | Move 0A to B register | |
| 4115 | CD,1A,41 | CALL BIN BCD | Call subroutine BIN BCD | |
| 4118 | 77 | MOV M,A | Move[A] to memory location | |
| 4119 | C9 | RET | Return to main program |
Subroutine 2
| Memory Location | Machine code | Label | Mnemonics | Comment |
| 411A | 36,FF | BIN BCD | MVI M, FF | Move FFh to memory location |
| 411C | 34 | NXTBUF | INR M | Increment memory pointer |
| 411D | 90 | SUB B | Subtract B from accumulator | |
| 411E | D2, 1C, 41 | JNC NXT BUF | Jump on no carry to NXT BUF | |
| 4121 | 80 | ADD B | Add the content of B register with accumulator | |
| 4122 | 23 | INX H | Increment memory pointer | |
| 4123 | C9 | RET | Return to subroutine1 |
c) Binary to ASCII
ALGORITHM:
- Initialize stack pointer
- Initialize register pair as source pointer
- Initialize DE register pair with destination pointer
- Move contents of memory pointer to accumulator
- Shift higher order nibble to lower order nibble by rotating the accumulator contents to right for 4 times
- Call subroutine
- Store the converted number in memory location 4300 and 4301
- End of execution
SUBROUTINE
- And immediately the binary data with 0Fh & mask the higher order bit & store it in the accumulator.
- Compare the accumulator content with 07
- If caryt results add 30h to the number else add 37h to the number
- Return to main program
| Memory Location | Machine code | Label | Mnemonics | Comment |
| 4100 | 31,FF,4F | LXI SP, 4FFF | Initialize stack pointer | |
| 4103 | 21, 00, 42 | LXI H,4200 | Initialize HL register pair with a source pointer | |
| 4106 | 11,00,43 | LXI D 4300 | Initialize DE reg pair with destination pointer | |
| 4109 | 7E | MOV A,M | Move M to accumulator | |
| 410A | 47 | MOV B,A | Move A to B register | |
| 410B | 0F | RRC | Rotate the accumulator content to right | |
| 410C | 0F | RRC | Rotate the accumulator content to right | |
| 410D | 0F | RRC | Rotate the accumulator content to right | |
| 410E | 0F | RRC | Rotate the accumulator content to right | |
| 410F | CD,1A,41 | CALL SUB | Call subroutine SUB | |
| 4112 | 12 | STAX D ` | Store the first ASCII value in 4300 | |
| 4113 | 13 | INX D | Increment memory pointer | |
| 4114 | 78 | MOV A,B | Move B to accumulator | |
| 4115 | CD,1A, 41 | CALL SUB | Call subroutine SUB | |
| 4118 | 12 | STAX D | Store the second ASCII value in 4301 | |
| 4119 | 76 | HLT | End of execution |
SUBROUTINE
| Memory Location | Machine code | Label | Mnemonics | Comment |
| 411A | E6,0F | SUB | ANI 0F | Mask higher order nibble |
| 411C | FE,0A | CPI 0A | Compare A with 0A | |
| 411E | DA, 23, 41 | JC loop | Jump on carry loop | |
| 4121 | C6,07 | ADI 07 | Add immediately 07 | |
| 4123 | C6,30 | Loop | ADI 30 | Add immediately 30 with accumulator |
| 4125 | C9 | RET | Return to main program |
d. ASCII to Binary
ALGORITHM:
- Initialize stack pointer
- Initialize register pair as source pointer
- Initialize DE register pair with destination pointer
- Move contents of memory pointer to accumulator
- Call subroutine
- Store the result in destination address
- End of execution
SUBROUTINE
- Subtract 30h from accumulator
- If the result is less that 0A, return to main program
- Else subtract 07h from the result
- Return to main program
| Memory Location | Machine code | Label | Mnemonics | Comment |
| 4100 | 31,FF,4F | LXI SP, 4FFF | Initialize stack pointer | |
| 4103 | 21, 00, 42 | LXI H,4200 | Initialize HL register pair with a source pointer | |
| 4106 | 11,00,43 | LXI D 4300 | Initialize DE reg pair with destination pointer | |
| 4109 | 7E | MOV A,M | Move M to accumulator | |
| 410A | CD,0F,41 | CALL SUB | Call subroutine SUB | |
| 410D | 12 | STAX D | Store the result in 4300 | |
| 410E | 76 | HLT | End of execution |
SUBROUTINE
| Memory Location | Machine code | Label | Mnemonics | Comment |
| 410F | D6,30 | SUB | SUI 30 | Subtract 30h from accumulator |
| 4111 | FE,0A | CPI 0A | Compare 0A with accumulator content | |
| 4113 | D8 | RC | Move the smallest number to memory location | |
| 4114 | C6,07 | SUI 07 | Subtractiimmediately 07 | |
| 4116 | C9 | RET | Return to main program |
Result:
Thus the assembly language program for code conversion like BCD to binary, Binary to BCD, Binary to ASCII and ASCII to Binary were performed.
Comments
Post a Comment