Write an assembly language program to convert lowercase to uppercase?

inc bx ; next char.

loop upper_case

; int 21h / ah=09h - output of a string at ds:dx.

; string must be terminated by '$' sign.

lea dx, string+2

mov ah, 09h

int 21h

jmp start ; loop

; wait for any key press....

mov ah, 0

int 16h

null:

ret