why are computer connections ...

why are computer connections so proprietary? the bits at the back of the computer are standard, parallel ports, usb ports and the like. why are the bits at the other end all different? why won’t a cable that fits an olympus digital camera connect to a fujifilm one? how the hell do i replace a fujifilm camera’s usb cable when fujifilm don’t even sell it as an accessory? there are other ways to get the pics of the smart media cards onto the computer but the cable’s the easiest way. i just want to buy another one and i can’t and i’m frustrated and i want to look at my pictures.