Method and apparatus for concurrently supporting multiple levels of keyboard display terminal functionality on a single physical input/output controller interface in an information handling system

Claim 1

In a display data terminal system including a host processor, an input/output controller connected to said host processor and a plurality of input/output keyboard-display devices connected to said input/output controller by respective transmission links, each of said input/output keyboard-display devices including logic interfacing with a corresponding one of said transmission links and providing communication between said input/output controller and a byte addressable buffer, the improvement wherein said input/output keyboard-display devices may be a first, second and/or third type device each having a different level of functionality and said input/output controller providing a single physical interface to all said input/output keyboard-display devices regardless of the respective level of functionality of each said input/output keyboard-display device, said first type input/output keyboard-display device having a lowest level of functionality permitting direct input to said host processor via its keyboard through said interfacing logic and wherein the addressable buffer of said first type of input/output keyboard-display device provides presentation space for a display monitor to receive output directly from said host processor through said interfacing logic, said second type input/output keyboard-display device having a highest level of functionality and including processing means for permitting both input to said host processor via its keyboard through said interfacing logic while supporting additional functions and wherein the addressable buffer of said second type of input/output keyboard-display device provides a terminal control area which receives output from said host processor through said interfacing logic and interfaces with said processing means for generating an output to a display monitor, and said third type input/output keyboard-display device having a dual level of functionality permitting operation in either a first mode at said lowest level of functionality or in a second mode at said highest level of functionality and wherein the addressable buffer of said third type of input/output keyboard-display device provides both presentation space and a terminal control area, the presentation space of the buffer of said first type of input/output keyboard-display device and the terminal control area of the buffer of said second type of input/output keyboard-display device have a common base address and the presentation space and the terminal control area of the buffer of said third type of input/output keyboard-display device have different base addresses, said input/output controller at power on polling each of said plurality of input/output keyboard-display devices and receiving responses from the interfacing logic of each said device identifying said device by functionality type and mode and, for input/output keyboard-display devices of said third type, translating an origin address of data from said host processor to a base address for said terminal control area when an input/output keyboard-display device of said third type is operating in said second mode permitting said input/output controller to concurrently support multiple modes of functionality of input/output keyboard-display devices of said third type.