A modular bus permitting single or double termination is described. The bus includes a terminated motherboard data net for communicating data signals between a master and one or more motherboard devices. A socket is used for coupling the data signals between the motherboard data net and a terminated module data net of a removable module. The module data net communicates the data signals between the master and one or more module devices. The data signal swing and level of reflection of the data signals are substantially independent of the presence of the module.