Data bus structure for use with multiple memory storage and driver receiver technologies and a method of operating such structures

Abstract

The disclosed invention relates generally to electronic data storage systems that access data storage memory modules via a data bus comprised of multiple data query lines and, more particularly, to an electronic data storage system provided with a data bus that can be selectively provided with terminations thereby permitting the data storage memory to use either modules that require that the data query lines be open-ended, i.e., without terminations or modules that require that the data bus be terminated and to a method for operating such a system. The present invention is particularly directed to a single memory system that can accommodate either 3.3V DIMMs or DDR DIMMs. This is especially accomplished by providing the processor circuit, used in memory storage systems, with both (3.3V) receiver/driver circuits and double rate (DDR) receiver/driver circuits, with an identification circuit for identifying the type of DIMMs in the memory system coupled thereto, a selection circuit for selecting the receiver/driver circuits required to access the identified DIMMs, and switch for adding or removing terminations to the data query lines, interconnecting the selected receiver driver circuits to identified DIMMS. Thus the invention provides a memory system that can access either 3.3V DIMMs or DDR DIMMs and automatically provide the proper terminations on the data bus used to access the DIMMs.