Method for preserving DOS compatibility using remote IO subsystems.
Original Publication Date: 2001-Dec-25
Included in the Prior Art Database: 2003-Jun-17
This invention solves the problem of preserving full DOS compatibility when designing large enterprise-class servers utilizing based processors. This invention achieves full DOS compatibility using a minimum number of signals to communicate between the CPU portion of the computer and the remote IO subsystem. This invention is applicable to implementations where the CPU complex and IO complex are physically separated by distances exceeding 15 meters. The main advantage of this invention is that full DOS compatibility can be preserved using a minimum of signals between the two physically separated subsystems. This invention creates an interface between the CPU subsystem and the remote IO subsystem to accommodate the communications of DOS compatibility signals between the two subsystems. The following describes an example interface between the two subsystems. However, this invention does not limit itself to this implementation only. The interface between the CPU subsystem and the IO subsystem is a combination of electrical signals, referred to as sideband signals. The sideband interface uses a 20 pin MDR cable. The cable will contain an assembly of 10 twisted pairs surrounded by a shield. The pairs can either be single-ended or differentially driven, depending on the cable length between the two subsystems. The cable will contain full duplex serialized sideband buses (one in each direction). The twisted pairs are assigned as follows: 1. CEC-IO Serial Data