paint16b was created by Hellmood and is 16 bytes in size. paint16b implements a mouse-driven drawing program which has the ability to exit back to DOS and also display the mouse cursor.

org 100h ; code starts at 0x100 mov al , 0x12 ; assume ah = 0 ; set graphics mode to 640*480 inc bx ; assume bx = 0 ; set to 1 (show cursor) mloop: int 0x10 ; first loop, switch to graphic mode ; further loops, set pixel xchg bx , ax ; first loop, set AX to 1 (show cursor) ; further loops, restore old calling mode xor al , 0x02 ; switch modes : show cursor <-> get mouse state ; updating XY every second loop plus drawing ; one pixel left results in thicker lines int 0x33 ; call the mouse interrupt xchg bx , ax ; store the button state in AL for drawing ; remember the current calling mode ; for switching it later (in BX) mov ah , 0x0C ; set mode to "set pixel" loop mloop ; dec CX -> draw one pixel left from cursor ; basically enables drawing pixels ; while the cursor is active ; allows exit if the mouse is leftmost ret ; assume [[FFEE]] = [0] = CD20 = int 20