Draw a flag (which size you want) [Intel 8086]

.8086
.model small
.stack 2048

dseg    segment para public 'data'

    ;this is the total size of flag, but somewhere above, you will see that
    ;I just decrement the left, right and middle column, and then
    ;when I jump between them, I use that value, without subtract by 2
    ;Remember, columns are "words" (theory) so, insted divide by 2 and multiply
    ;again, I just leave it as it is

    ;total size
    maxColumns  dw  69      ;includes left, right and middle columns
    maxLines    dw  19      ;same with lines
    toNextLine  dw  ?

dseg    ends

cseg    segment para public 'code'
assume  cs:cseg, ds:dseg

Main  proc
    mov ax, dseg
    mov ds, ax
    mov ax,0b800h       ;B800 is the video memory adress
    mov es,ax           ;move that adress to es
                        ;es stands for "extra segment"

    ;code to clear screen (shared before)
    mov bx, ' '     ;space to bx. A space is what we will write in screen (to clean)
    xor di, di      ;di -> 0
    mov cx, 24*80   ;24*80 is the size of window! 24 lines,80 columns

clear:
    mov es:[di], bx ;move the space to video adreess (in other words, write a space on screen)
    add di, 2       ;every video adress have a size of word, so let's add 2
    loop clear      ;repeat until cx = 0, In every loop, cx is decremented


    ;draw the flag
    mov bl, 00100000b       ;[0][010][0000]b -> binary (*see below)


    mov bh, '*'             ;this is the char we will print
    xor di, 320             ;the position we will start
    xor si, 320             ;in this case we will start e second line

    mov cx, maxColumns      ;let's draw the top line
theTop:
    mov es:[si], bh
    mov es:[si+1], bl
    add si, 2
    loop theTop             ;done!


    mov cl, 2               ;now, calculate the middle line
    mov ax, maxLines
    dec ax
    div cl                  ;and the result will be saved in ax

    sub maxLines, 2         ;subtract 2 lines (top and bottom)
                            ;the middle line will be decremented after

    sub maxColumns, 3       ;decremente 3 columns (left, middle and right)
    mov dx, maxColumns      ;save value in ax


    mov toNextLine, 160     ;calculate ao much columns we need to jump
    sub toNextLine, 6       ;until next line
    sub toNextLine, dx
    sub toNextLine, dx      ;the result will be in toNextLine

    add si, toNextLine      ;now, jump to next line, because um print the top
                            ;but we have more to print

drawFlag:

    mov es:[si], bh         ;print left column
    mov es:[si+1], bl

    add si, 2               ;jump this columns
    add si, maxColumns      ;and the necessary number of columns until the middle

    mov es:[si], bh         ;print middle column
    mov es:[si+1], bl

    add si, 2               ;again, jump to right column
    add si, maxColumns

    mov es:[si], bh         ;print right column
    mov es:[si+1], bl

    add si, 2
    add si, toNextLine      ;add the number of columns until next line

    dec maxLines            ;decrement lines
    cmp maxLines, ax        ;check if we are in the middle line
    jne keepGoing           ;if not, keep print the flag

    mov cx, maxColumns      ;if yes, print the middle line
    add cx, 3               ;add 3, because we decrement 3 before
theMiddle:
    mov es:[si], bh
    mov es:[si+1], bl
    add si, 2
    loop theMiddle

    dec maxLines            ;after middle line is printed, decremente one line
    add si, toNextLine      ;and jump to next line
keepGoing:
    cmp maxLines, 0         ;compare if we are in last line
    jne drawFlag            ;if not, keep print the flag

;++++++++++++++++
    mov cx, maxColumns      ;and now, print the bottom line of flag
    add cx, 3               ;add 3 again
theTail:
    mov es:[si], bh
    mov es:[si+1], bl
    add si, 2
    loop theTail            ;done!


    mov ah,4CH
    int 21H
main    endp

cseg    ends
end     main

;the first 0 means static, if 1, text will be blinking
;the next 3 digits is for brackground color [000-111]
;the next 4 digits is for text color [000-1111]
;colors
;black          0000
;blue           0001
;gren           0010
;cyan           0011
;red            0100
;magenta        0101
;brown          0110
;light grey     0111
;dark grey      1000
;light blue     1001
;light green    1010
;light cyan     1011
;light red      1100
;light magenta  1101
;yellow         1110
;white          1111