165 results about "Extended memory" patented technology

The utility of portable computer hosts, such as PDAs (or hand-helds), is enhanced by methods and apparatus for removable expansion cards having application specific circuitry, a second-level-removable memory, and optional I / O, in a number of illustrative embodiments. In addition to providing greater expansion utility in a compact and low profile industrial design, the present invention permits memory configuration versatility for application specific expansion cards, permitting easy user field selection and upgrades of the memory used in conjunction with the expansion card. Finally, from a system perspective, the present invention enables increased parallelism and functionality previously not available to portable computer devices.

A database system providing methodology for extended memory support is described. In one embodiment, for example, a method is described for extended memory support in a database system having a primary cache, the method comprises steps of: creating a secondary cache in memory available to the database system; mapping a virtual address range to at least a portion of the secondary cache; when the primary cache is full, replacing pages from the primary cache using the secondary cache; in response to a request for a particular page, searching for the particular page in the secondary cache if the particular page is not found in the primary cache; if the particular page is found in the secondary cache, determining a virtual address in the secondary cache where the particular page resides based on the mapping; and swapping the particular page found in the secondary cache with a page in the primary cache, so as to replace a page in the primary cache with the particular page from the secondary cache.

Described is a system and method whereby processes may have multiple memory maps associated therewith to provide curtained memory and overcome other memory-related problems. Multiple maps are used to restrict memory access of existing code such as drivers, without changing that code, and without changing existing microprocessors. A thread of a process is associated with one memory map at a time, which by mapping to different memory locations, provides memory isolation without requiring a process switch. Memory isolation may be combined with controlled, closed memory map switching performed only by trusted code, to ensure that some protected memory is inaccessible to all but the trusted code (curtained memory). For example, the threads of the process may ordinarily run at one privilege level with a restricted map, with map switching is only allowed at a higher privilege level. As the threads run through code, the map may be appropriately changed on entering and leaving the trusted code, thus controlling what memory addresses are accessible based on what code is currently being executed. Map switching among multiple maps eliminates the need to change a process in order to access different memory, thereby allowing expanded memory addressing in a single process and isolating untrusted code run in process from certain memory of that process.