Basic

Printing using interrupts
org 100h
     mov     ah, 0x9 ;for printing
        mov     dx, offset  hello;loading offset of hello world in dx
        int     0x21  ;dos interrupt to print

mov     ax, 4ch;terminating program
        int     21h

hello:  db 'Hello world $';$ is used for terminating string

Printing with color using interrupts

;This program shows how to print with colours
;colours are from 0 to 255
;numbers 16 and onward will give colorful background
org 100h

    xor ax,ax ;same as, mov ax,0
    lea dx, message
    mov bl,10 ;different number will produce different colours
    mov ah, 9
    int 10h   ;interrupt for colours
    int 21h
       
mov ah,4ch;terminating
int 21h                            

;we can also declare variables or strings here
message dw 'Smile please :)','$'

Printing using video memory

org 100h
jmp start
str db "Hello world"
start:

mov ax, 0xb800;for accessing video memory, as we want to print some thing on screen
mov es, ax  

xor di, di ; same as mov di, 0
xor si, si ; same as mov si, 0  
;printing string
print:
mov al, [str+si]    ;moving value from str to al
mov byte es:[di],al ;printing value of al
mov byte es:[di+1],0x07;color attribute,you can change it
add si,  1;Moving si one index forward
add di,  2;Moving di two index forward
          ;because di has char and di+1 has color attribute so, next char should be at di+2
cmp di, 22;str is of 11 byte, which means str will end when di=22
jne print
MOV AH, 4CH  ;terminate program
INT 21H

Printing with color using video memory

;This program accesses video memory and prints data
;colours are from 0 to 255
;numbers 16 and onward will give colorful background
org 100h
jmp start
str db "Hello world"
start:

mov ax, 0xb800;for accessing video memory, as we want to print some thing on screen
mov es, ax  

xor di, di ; same as mov di, 0
xor si, si ; same as mov si, 0    
;printing string
print:
mov al, [str+si]    ;moving value from str to al
mov byte es:[di],al ;printing value of al
;******************************************************
mov byte es:[di+1],10d;I have changed it to get colours
;******************************************************
add si,  1;Moving si one index forward
add di,  2;Moving di two index forward
          ;because di has char and di+1 has color attribute so, next char should be at di+2
cmp di, 22;str is of 11 byte, which means str will end when di=22
jne print
MOV AH, 4CH  ;terminate program
INT 21H

Printing Shapes

;shapes are in between 1 to 5 asci
org 100h

mov ax,0d;taking 64 in decimal
mov cx,0;counter
loop:

add ax,1
add cx,1

mov dx ,ax
mov ah , 2h
int 21h ; interrupt for printing

cmp cx,6
jne loop

end:
MOV AH,4CH;terminating program
INT 21H