Seattle ? Apple Inc. updated its iMac desktop computer line Tuesday and introduced a mouse that responds to the touch of fingers instead of using buttons or scroll wheels.

The updated iMacs have bigger screens — 21.5 inches and 27 inches, compared with existing models’ 20 inches and 24 inches. They also have speedier processors and better graphics. The least expensive model costs $1,199, the same as the past generation, but the top-of-the-line iMac is now $200 cheaper at $1,999.

The wireless Magic Mouse, as Apple calls it, will be sold standard with iMacs or by itself for $69.