Node adapted for backplane bus with default control

DETAILED DESCRIPTION It is therefore an object of the present invention to ensure reliable operation of a computer system bus by providing a node to drive the bus to a defined logic level whenever the bus is otherwise not being used by the computer system.
Another object of the invention is to drive such a bus by a node using electronic circuits utilizing CMOS (Complementary Metal Oxide Semiconductor) technology without need for interfacing through non-CMOS devices.
Additional objects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description or may be learned by practice of the invention.
The objects and advantages of the invention will be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
To achieve the objects and in accordance with the purpose of the invention, as embodied and broadly described herein, a node of this invention(adapted for connection to an extend bus cycle line, which indicates that a multi-cycle transfer is being performed, and to a backplane system bus which carries data first and second logic levels, the bus being biased at a voltage level intermediate the first and second logic levels.
The node of this invention is also adapted to be responsive to arbiter means for detecting the lack of a bus request for a next cycle on the bus and comprises default generator means, adapted to be connected to the extend bus cycle line and the arbiter means, for generating a default bus signal during cycles when there is a lack of activity on the bus; and logic circuit means adapted to be coupled to the bus for selectively transmitting the data carried on the bus, the logic circuit means including means coupled to the default generator means for receiving the default bus signal and driving the bus to one of the first and second logic levels, instead of allowing the bus to assume the intermediate voltage level, upon detection by the default generator means of the lack of activity on the bus