Abstract: A method and apparatus for visually comparing two files or portions thereof by visually indicating to the user areas of identity and differences between the items being compared. The items are stored in a video RAM which controls the visual presentation on the screen. The respective pixel settings in the video RAM are exclusively or'ed and the results are then stored in the video RAM so that the difference between the two items are displayed. A user can edit each item, while the comparison is being made, so that the effect of the editing on the differences, is immediately shown and apparent to the user.