Generate and display BCD up counter with frequency 1Hz

Statement: Write a program for displaying BCD up counter. Counter should count numbers from 00 to 99H and it should increment after every 1 sec. Assume operating frequency of 8085 equal to 3MHz. Display routine is available.

Source program:

• LXI SP, 27FFH : Initialize stack pointer
• MVI C, OOH : Initialize counter
• BACK: CALL Display : Call display subroutine
• CALL Delay : Call delay subroutine
• MOV A, C
• ADI A, 0 1 : Increment counter
• DAA : Adjust it for decimal
• MOV C,A : Store count
• CPI ,00 : Check count is > 99
• JNZ BACK : If not, repeat
• HLT : Stop

Delay Routine:

• Delay:MVI B, Multiplier-count           : Initialize multiplier count
• BACK 1                                               :LXI D, Initialize Count
• BACK:DCX  D                                       : Decrement count
• MOV A, E
• ORA D                                                 : Logically OR D and E
• JNZ BACK                                           : If result is not a, repeat
• DCR B                                                 : Decrement multiplier count
• JNZ BACK 1                                        : If not zero, repeat
• RET                                                     : Return to main program.