assume cs:code

code segment
org 100h
.386
start:

mov ax,0a000h
mov es,ax

mov ax,13h
int 10h

mov di,0
mov ax,0

loop1:
 mov es:[di],al
 inc ax
 inc di
 cmp di,64000
jne loop1

loop3:
mov di,0
loop2:
 inc byte ptr es:[di]
 inc di
 cmp di,64000
jne loop2
jmp loop3

ret

code ends
end start