re power supplies simply one way that hardware manufacturers boost margins in a competitive market? These questions started arising when my MacBook Pro’s power supply cable fell apart (on the Mac side) as the copper in the cable sheared off, presumably from repeated bending and the only Apple stores available to me in Madison, Ind., were on the other side of Louisville, Ky., about 60 miles away or 75 miles or so away up the river in Cincinnati. Some Wal-Marts carry Apple computing products, but not the one in my hometown. Best Buys also carry them, but none were nearer than the two metropolitan areas. It’s not much of a selling point to have someone like me saying that Macs are great if you cannot get parts. (The same thing happened to the power cord on my daughter’s Mac last year). More galling was that the local Wal-Mart had ample power cords for iPhones, iPads and iPhones, which have a different port than a Mac. If I were trying to convince people to buy as many Apple products as possible, I’d want to have these things be highly interchangeable.