Go4Expert - Counters using the delay routine.

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Counters using the delay routine.

Introduction

I get lots of emails and PM to write some more Assembly language programs and as I have some time I thought of writing some more.

Its called Counters using the delay routine.

Subroutine

The subroutine we will use is as follows. This will behave as a delay for our counter

Code:

//FUNC

   MVI C, FF

   // Load Register C with the Hex value FF

   DCR C

   // Decrement the C Register // Address of the statment is XXXX

   JNZ XXXX

   // loop till you get the counter reduced to zero

   RET

Now we will write the actual program to have the counter

Code:

   LXI SP, 87DD

   // Load immediate stack pointer

   LXI H, 0000

   // Load immediate register Pair H & L

   MVI B, 10

   // Load Register B with the Hex value 10

   SHLD 87FD

   // Store H & L direct

   PUSH B

   // Push register Pair B & C on stack

   CALL FUNC

   // Call the above subroutine

   POP B

   // Pop register Pair B & C off stack

   DCR B

   // Decrement B

   JNZ XXXX // - SHLD Location

   // Jump on no zero

   INX H

   // Increment H & L registers

   JMP XXXX // MVI B 10 location

   // Jump unconditional

Now to make the decrement counter you just need one change INX to DCX