As more peripherals were added, it soon became clumsy to have a separate instruction for each device, especially if not all computer systems were equipped with the same devices. Instructions became more abstract, mentioning only a port number instead of hard-coding whether it was a printer, a plotter or a card reader. I/O instructions became simpler, and only two, IN and OUT, were sufficient. The Intel x86 line of microprocessor chips keeps up this grand tradition, long after mainframes had moved onto grander schemes, and even today the fanciest of the Pentium chips still have an IN and an OUT instruction.