Lets consider a simple program fragment in C.

    prod = 1;
    for( index=2; index--; )
    {
      prod += index;
    }
  

Translated into assembly code, that code could look something line this.

           MVI 1,R0		; prod = 1
           MVI 2,R2		; index=2
    Loop1:
           ADD R0,R2		; prod + index
           MOV ACC,R0		; prod =
           DCR R2		; index-1
           MOV ACC,R2		; index =
           JNZ Loop1		; for()
  

Explaining that code:

• ADD r1,r2
  Add registers r1 and r2 and store the result in the Accumulator ACC.
• DCR r
  Decrement register r and put the result into the Accumulator ACC.
• JNZ a
  Jump to address a if the value in the Accumulator ACC is not zero.
• MOV r1,r2
  Copy the contents of register r1 to r2.
• MVI v,r
  Load register r with the value v.