--- title: "8086 ALP: words on lines and word count" subject: "Microprocessor" chapter: 3 key: "semester_4/microprocessor:alp-8086-words-lines-count" source: https://www.bctengineer.com/q/semester_4/microprocessor/alp-8086-words-lines-count site: BCT Engineering --- # 8086 ALP: words on lines and word count Microprocessor · Chapter 3: Programming with 8086 Microprocessor - Asked in: 2070 Bhadra, 8 marks - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_4/microprocessor/alp-8086-words-lines-count - Whole chapter: https://www.bctengineer.com/md/semester_4/microprocessor/chapter-3 ## Question Write an assembly language program for 8086 to read a string. Display each word in separate lines in a cleared screen, count how many words are there and display the count. ## Short answer Read string, clear screen, scan words, print each word followed by CRLF, increment counter, display count in decimal. Example I love Nepal prints three lines and Number of words = 3. ## Answer **Method:** clear the screen after input, then scan the string. Blanks are skipped; each word is displayed character by character and followed by a new line (CR, LF), and the word counter `WCNT` is incremented. At the end the count is displayed in decimal using `PRINT_DEC`. The string ends with the Enter code 0DH. ```asm .MODEL SMALL .STACK 100H DISPSTR MACRO MSG ; display a '$'-terminated string LEA DX,MSG MOV AH,09H INT 21H ENDM CLRSCR MACRO ; clear screen and home the cursor MOV AX,0600H ; scroll whole window (AL=0 -> blank it) MOV BH,07H ; normal attribute MOV CX,0000H ; upper-left corner (row 0, col 0) MOV DX,184FH ; lower-right corner (row 24, col 79) INT 10H MOV AH,02H ; set cursor position MOV BH,00H ; page 0 MOV DX,0000H ; row 0, col 0 INT 10H ENDM .DATA MSG1 DB 'Enter a string: $' MSG2 DB 'Number of words = $' WCNT DB 0 BUF DB 80, ?, 80 DUP(0) ; DOS buffered-input area (max, actual, chars) CRLF DB 13,10,'$' .CODE MAIN PROC MOV AX,@DATA MOV DS,AX DISPSTR MSG1 ; prompt LEA DX,BUF ; read the string with DOS function 0Ah MOV AH,0AH INT 21H CLRSCR LEA SI,BUF+2 NEXT: MOV AL,[SI] CMP AL,0DH JE DONE ; end of string CMP AL,' ' JNE WSTART INC SI ; skip blank JMP NEXT WSTART: ; a word starts here INC WCNT ; count it PR: MOV DL,[SI] INC SI MOV AH,02H INT 21H ; display character MOV AL,[SI] CMP AL,' ' JE ENDW CMP AL,0DH JNE PR ENDW: DISPSTR CRLF ; word finished -> new line JMP NEXT DONE: DISPSTR MSG2 MOV AL,WCNT XOR AH,AH CALL PRINT_DEC ; display number of words MOV AH,4CH ; return to DOS INT 21H MAIN ENDP ; ---- print the unsigned number in AX in decimal (registers preserved) PRINT_DEC PROC PUSH AX PUSH BX PUSH CX PUSH DX MOV BX,10 XOR CX,CX ; digit counter PD1:XOR DX,DX DIV BX ; AX = quotient, DX = remainder (digit) PUSH DX INC CX OR AX,AX JNZ PD1 PD2:POP DX ; digits come out in correct order ADD DL,30H ; to ASCII MOV AH,02H INT 21H LOOP PD2 POP DX POP CX POP BX POP AX RET PRINT_DEC ENDP END MAIN ``` **Example:** `I love Nepal` → lines `I`, `love`, `Nepal`, then `Number of words = 3`. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. When is the word counter WCNT incremented? A. For every character B. For every space C. When a new word starts after skipped blanks D. Only at the end of the string Answer: C. WCNT is incremented at WSTART, once for each word found after blanks are skipped. (Key point: Word counting) 2. How is each word shown on its own line? A. A CR,LF string is displayed after each word B. The cursor is set with INT 10h C. Words are stored in separate buffers D. A tab is printed between words Answer: A. After the word is printed, DISPSTR CRLF moves to the next line. (Key point: Separate lines) 3. How does the scan detect the end of the input? A. A '$' character B. A zero byte C. The count in BUF+1 reaching 0 D. The Enter code 0DH Answer: D. Function 0Ah stores 0DH after the last typed character. (Key point: String end) 4. When is the screen cleared? A. After the string is read, before the words are displayed B. Before the prompt is shown C. After the count is displayed D. After each word Answer: A. The screen is cleared after input so only the words and the count appear. 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