SCREEN 0, 0
CLS
DEF SEG = &HB000
FOR y = 0 TO 15
        FOR x = 0 TO 15
                addy = x * 4 + y * 160
                POKE addy, x + y * 16
                POKE 1 + addy, 10
                POKE addy + 2, x + y * 16
                POKE 3 + addy, 2
        NEXT x
NEXT y