Abstract: An adapter and control card system for a digital computer is provided for coupling the digital computer to a selectable choice of communications media. The system includes a general-application host card removably insertable into the digital computer, and a communications-medium-specific adapter card removably insertable into the host card, the host card having a cutout conforming to side and end boundaries of said adapter card, the adapter card fitting within the cutout along a substantially common plane in order to minimize surface height of the adapter card and the host card. Mating connectors, particularly between the adapter card and the host card, form transmission lines taking full advantage of ground pins adjacent to signal-carrying differential pairs shielding the signals with a controlled characteristic impedance. In a specific embodiment, the support structure for the connectors also forms the mechanical support for the adapter card and the host card.

Abstract: An FDDI transmitting apparatus employs a scrambler to scramble input NRZ data which in turn is input to an NRZI-to-NRZ pre-encoder. This is in turn coupled in series with an NRZ-to-NRZI encoder to produce scrambled FDDI data for transmission whose spectral content is predistorted as a result of the scrambling to minimize spectral content peaks above about 30 MHz. The scrambling is performed according to the equation y.sub.i =x.sub.i +y.sub.i-14 +y.sub.i-15. A complementary receiving apparatus employs an NRZI-to-NRZ decoder which, according to the invention, is coupled to an NRZ-to-NRZI postdecoder. This data is thence coupled to a descrambler according to the invention to recover the original data.

Abstract: An FDDI transmitting apparatus employs a scrambler to scramble input NRZ data which in turn is input to an NRZI-to-NRZ pre-encoder. This is in turn coupled in series with an NRZ-to-NRZI encoder to produce scrambled FDDI data for transmission whose spectral content is predistorted to minimize spectral content peaks above about 30 MHz. A complementary receiving apparatus employs an NRZI-to-NRZ decoder which, according to the invention, is coupled to an NRZ-to-NRZI postdecoder. This data is thence coupled to a descrambler according to the invention to recover the original data.

Abstract: An apparatus for measuring the alignment of two or more adjacent targets while the targets are in motion is provided. The alignment measuring apparatus includes a plurality of alignment scanners, each adapted to detecting the arrival of an associated target. A speed scanner is spaced apart from the alignment scanner for detecting said first one of the targets. First timing means are provided for measuring a first time differential indicative of the time delay between detection of the leading and trailing targets by the alignment scanners to provide a measurement proportional to the misalignment between the targets.