>"BLVDS (Bus LVDS) - National Semiconductor Desiring to extend the benefits of LVDS, National invented Bus LVDS (a.k.a. BLVDS). This was targeted at heavily loaded backplanes where card loading and spacing lowers the impedance of the transmission line as much as 50%. This loading effect, and the need to terminate the bus at both ends for multipoint applications, required a change to the driver's output. National boosted the output three fold to the 10-12 mA range. A 100-Ohm transmission line, loaded down to 54 Ohms by the cards, would then need to be terminated at both ends in 54 Ohms. Thus a driver would see the two terminations in parallel and need to drive a load of 27 ohms minimum (higher is acceptable also). Thus for LVDS signaling levels, with a 27 ohm load, 12 mA is needed to generate 325 mV swing. Other improvements were made to the driver to further match the drivers output impedance and to make it contention safe. This has changed the world of backplane driving, the old solution was to throw more current at the problem (i.e. GTL uses 40 to 80 mA), while BLVDS reduces output current to the 10 mA range. Today there are three classes of BLVDS parts offered by National. The first is standard transceivers for multipoint buses. National offers these in single, quad, or nine channel versions. The card connectors, and stub lengths will limit signal quality in this type of bus configuration to the 200 to 400 Mbps range, which is still an impressive 2X to 4X of single-ended GTL or BTL based systems. The next class is SER/DES devices that serialize data and clock into a single serial stream. The bus configuration for serial streams can be multidrop (if data rate is less than 400 Mbps) or point-to-point (typically for data rates greater than 400 Mbps) applications. The connector pin savings, and in some cases fewer backplane layers, can offer huge system cost savings. The third class is special functions devices. These solve special problems such as bus repeating, redundant path cross-overs, and crosspoint switches. BLVDS has addressed a wide market space ranging from telecom infrastructure and datacom to storage applications where card density demands high-performance backplanes. Several vendors now offer BLVDS like devices, and its popularity is increasing every day"

PDS: I wonder if Bus LVDS -- would make a good bus replacement for PCI Express -- at least for hobbyist projects where speed -- isn't as important as simplicity and open hardware / open protocols / open standards...