This is a code that must be tested through notepad and it must determine whether or not its condition is based on the use of strings:

.MODEL SMALL

.STACK

.DATA

NEWLINE db 0Dh, 0Ah, '$'

PROMPT db "Entre una cadena de caracteres: ",'$'

CHARACTER db ?

STRING db 81 dup('$')

MAX_LEN equ 80

CARRIAGE_RETURN equ 0Dh

LINE_FEED equ 0Ah

IS_VALID db ?

UNSIGNED_INT dw ?

TRUE equ 1h

FALSE equ 0h

.CODE

MAIN PROC

mov ax, @DATA

mov ds, ax

call NEW_LINE

call SHOW_PROMPT

call ASK_STRING

call NEW_LINE

call NEW_LINE

call SHOW_STRING

call IS_UNSIGNED_INT

cmp byte ptr IS_VALID, FALSE

jz GO_NEXT

call STRING_TO_UNSIGNED_INT

add word ptr UNSIGNED_INT, 10

call UNSIGNED_INT_TO_STRING

GO_NEXT:

call SHOW_STRING

call NEW_LINE

call NEW_LINE

mov ax, 4c00h ; exit program

int 21h ; return AL

RET

MAIN ENDP

;***********************************************************************************

UNSIGNED_INT_TO_STRING PROC

mov ax, UNSIGNED_INT

mov bx, 10

mov di, 0h

ANOTHER:

mov dx, 0h

div bx

add dl, '0'

mov STRING[di], dl

inc di

cmp ax, 0h

jnz ANOTHER

mov STRING[di], '$'

dec di

mov si, 0

OTHER:

mov ch, STRING[di]

mov cl, STRING[si]

mov STRING[di], cl

mov STRING[si], ch

dec di

inc si

cmp si, di

jb OTHER

RET

UNSIGNED_INT_TO_STRING ENDP

;***********************************************************************************

STRING_TO_UNSIGNED_INT PROC

mov ax, 0h

mov cx, 0h

mov bx, 10

mov di, 0h

mov cl, STRING[di]

BACK:

cmp cl, '$'

jz CONVERTED

mul bx

sub cl, '0'

add ax, cx

inc di

mov cl, STRING[di]

jmp BACK

CONVERTED:

mov UNSIGNED_INT, ax

RET

STRING_TO_UNSIGNED_INT ENDP

;***********************************************************************************

IS_UNSIGNED_INT PROC

mov byte ptr IS_VALID, TRUE

mov di, 0h

mov ah, STRING[di]

NEXT_CHAR:

cmp ah, '$'

jz DECIDIR

cmp ah, '0'

jb DECIDIR

cmp ah, '9'

ja DECIDIR

inc di

mov ah, STRING[di]

jmp NEXT_CHAR

DECIDIR:

jnz NOT_VALID

cmp di, 0h

jnz KEEP

NOT_VALID:

mov byte ptr IS_VALID, FALSE

KEEP:

RET

IS_UNSIGNED_INT ENDP

;***********************************************************************************

SHOW_PROMPT PROC

mov dx, offset PROMPT ; write all characters

mov ah, 09h ; in the standard output

int 21h ; DX has the offset of the first character

RET ; the last character must be '$'

SHOW_PROMPT ENDP

;***********************************************************************************

SHOW_CHARACTER PROC

mov ah, 02h ; write a character to standard ouput

mov dl, CHARACTER ; DL has the character

int 21H

RET

SHOW_CHARACTER ENDP

;***********************************************************************************

ASK_CHARACTER PROC

mov ah, 08h ; read a character without echo from standard input

int 21h ; AL stores the character read

mov CHARACTER, al

RET

ASK_CHARACTER ENDP

;************************************************************************