Optimization of subsystem interconnections in an electronic device

Abstract

A subprocessor is used to interface between subsystems and to reduce the amount of dedicated hardware used to implement the subsystems in a hand-held computer. The subprocessor includes basic processing system resources such as random-access memory (RAM), read-only memory (ROM), a processor, input/output (I/O) facilities, etc. Selected functions in subsystems are achieved by firmware instructions executed by the subprocessor as opposed to a main processor that is also used in the computer. This approach can provide efficiencies such as low power consumption, less required space, less routing overhead, easier transfer of inter-subsystem information, and other advantages.

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         12 . A method for designing an electronic device in a system having N subsystems where the number of interconnections needed between subsystems is substantially a factor of N2, wherein each subsystem includes functionality, the method comprising: 
 Identifying the maximum of the subsystems' functionality that can be placed into a subprocessor; and    using the subprocessor to implement an interface between two or more of the subsystems that are placed into the subprocessor.    
     
     
         13 . The method of  claim 12 , further comprising: 
 analyzing a tradeoff between resource use and a performance criterion; and    attempting to minimize the resource use while not exceeding a predetermined threshold for the performance criterion.    
     
     
         14 . The method of  claim 13 , wherein the performance criterion includes execution speed.  
     
     
         15 . The method of  claim 13 , wherein the performance criterion includes latency.  
     
     
         16 . The method of  claim 13 , wherein the performance criterion includes memory use.  
     
     
         17 . The method of  claim 13 , wherein the resource use includes power consumption.  
     
     
         19 . The method of  claim 13 , wherein the resource use includes space.