Ex parte LOO et al. - Page 15




          Appeal No. 95-4714                                                          
          Application No. 08/046,476                                                  



               with a shared, multi-user operating system having                      
               multiple concurrently active contexts and a kernel;                    
                    main memory;                                                      
                    a memory management unit, coupled to said                         
               processor and said main memory, for translating an                     
               address in virtual space into a corresponding address                  
               in physical space;                                                     
                    a virtual cache data array, coupled to said                       
               central processing unit, for storing a first plurality                 
               of blocks of data;                                                     
                    a virtual cache tag array, coupled to said virtual                
               cache data array and said central processing unit, for                 
               storing a plurality of tag array elements wherein, each                
               tag array element corresponds to a particular block of                 
               data stored in said virtual cache data array and                       
               further includes: a validity bit, a modification bit, a                
               protection bit, a write allowed bit, a plurality of                    
               virtual address field bits, and a plurality of context                 
               bits;                                                                  
                    cache hit logic means, coupled to said processor                  
               and said virtual cache tag array, for determining                      
               whether accesses from said central processing unit                     
               result in a cache hit or a cache miss;                                 
                    cache flush logic means, coupled to said central                  
               processing unit and said cache hit logic means, for                    
               directing the flushing of said virtual cache data                      
               array;                                                                 
                    wherein said central processing unit includes                     
               means, disposed within the kernel of said shared,                      
               multi-user operating system, for coupling a context                    
               match flush command comprising a plurality of context                  
               identifier bits, to said cache flush logic means and                   
               said virtual cache tag array, such that in response to                 
               said context match flush command, said cache flush                     
               logic means flushes a first block of data from said                    
               virtual cache data array in the event that:                            
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