Question

Write an assembly code the counts the number of accuracies of the byte AAh in memory from address 120Ah to address 130Ah. You need to use a subroutine and call it 'COUNT' to do so. You also need to provide the count in BCD if it was less than 64h so that you need to include another subroutine called 'ToBCD' to do so.

assembly 8086

Answer 1

Greetings!!

Code:

;MAIN STARTS HERE

.CODE
MOV AX,@DATA
MOV DS,AX
  
CALL COUNT ;calling COUNT procedure to count the occurance of AA
  
HLT

;MAIN ENDS HERE

;procedure count definition
PROC COUNT NEAR
  
MOV AX,0 ;initialize AX with 0 for counting
MOV CX,100 ;load count into CX register[130A-120A=100].
MOV SI,120AH ;load the starting address into SI for reading the element from the memory
NEXT:
MOV BL,[SI] ;load the number into BL
INC SI ;point to next element in the memory
CMP AL,99H ;check the count less than 99
JNE CONTINUE ;if not 99 then continue   
CALL TOBCD ;if 99 call TOBCD procedure
CONTINUE:   
CMP BL,0AAH ;compare the number loaded from memory is AA or not
JNZ SKIP ;if not AA then skip
ADD AL,1 ;if AA, then increment the COUNT in AL
DAA ;adjust to BCD after each addition
SKIP:   
LOOP NEXT ;repeat the process
  
RET

;DEFINITION OF TOBCD FUNCTION   
PROC TOBCD NEAR

INC AH ;increment AH if the count in AL is 99
MOV AL,00 ;clear the AL count and start from 0 again
RET

Output screenshot:

Tested with more than 100 elements Iin an array and the count is shown below

Hope this helps