Business Notes COMPUTERS

Almost from the day Apple Computer introduced its Macintosh line in 1984, aficionados clamored for a portable version of the popular machine. This week Apple will finally unveil one. The delay was caused by the difficulty of producing a lightweight Mac with a graphics display as vivid as the larger models'. To achieve that clarity, insiders say, the new machine has an active- matrix screen, in which each of its thousands of picture elements will be controlled by an individual transistor. Instead of Apple's famous mouse, the new Mac has a cursor-control device called a trackball mounted on the keyboard.

Users of the new Mac (estimated price: $6,000 or more) will have to develop their biceps to handle the machine, which weighs about 16 lbs., compared with 4 lbs. for small IBM-compatible portables. Apple is taking pains to call the machine a portable rather than a laptop, but computer-industry wags have already dubbed it a "luggable." Even so, experts believe the Mac is likely to be a walkaway success.